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NI-488.2M Software Reference Manual

1. 6 qmumssapa be _ ibtrg Trigger selected device dev i ipert string Write data ibwrtf Write data to file brd 7 flname Table 6 2 Syntax for NI 488 2 Routines in ibic Routine Syntax Description AllSpoll list DevClear address DevClearList list EnableLocal list EnableRemote list continues National Instruments Corp 6 11 NI 488 2M Reference Manual ibic Chapter 6 Table 6 2 Syntax for NI 488 2 Routines in ibic Continued Routine Syntax Description FindLstn list limit Find all listeners FindRQS list Find dev requesting service PassControl address Pass control to a device 13 13 13 14 3 4 12 13 RcvRespMsg address data mode Receive Response Message Serial Poll 3 level Device reset Send command bytes Send Data Bytes Send Interface Clear Put devices in LLO SetRWLS list Put device in RWLS Device self tests Trigger several devices Wait for SRQ A oe p 4 12 13 4 12 13 4 11 12 4 11 12 11 11 11 NI 488 2M Reference Manual 6 12 National Instruments Corp Chapter 6 ibic Notes for Tables 6 1 and 6 2 1 brdname is the symbolic name of the new board for example ibbna gpibl 2 Values enclosed in square brackets are optional The default value is zero for ibwait and 1 for all other functions 3 visa hex octal or decimal
2. 5 7 Step 2 Clearing the Device 5 7 Step 3 Configuring the Device 5 8 Step 4 Triggering the Device 5 8 Step 5 Taking Measurements sse 5 8 Step 6 Analyzing and Presenting the Acquired Dat eite entere tese ter 5 9 The Complete Application Program 5 9 NI 488 Function Descriptions esee 5 10 BASK irme treten 5 11 IBBNA 3 5i tnettedatenetatetdge ded eniin 5 21 IBC AC 3 icio te oe He aec ee bt 5 22 IBCER 3 5 23 IBCMD iiti hia e edi ees 5 24 IBCONFIG 3 rte ete tere denti 5 26 IBDEV 3 ete ite depot ORE 5 36 IBDMA 3 eer ert ee UTER 5 38 IBEOS 3 eere tei tie dre 5 39 IBEQT ot Rei e Aoi tee 5 42 BENDo EE 5 44 IBGTS Een toit eie reete 5 46 IBIST 3 5 47 IBLINES 3 5 48 IBELO BJs hater eel ae epi tere teer 5 50 IBING coi oreet rare e ht peer eee it 5 51 IBEOG eee dep p 5 53 IBONE 3 Bc RR 5 55 IBPAD 3 egrets testa ate E End 5 57 IBPCT 3 tio ete etel 5 59 IBPPC 3 58i ete eme A Reb etes 5 60 IBRD 3 e t OR 5 62 IBRDE G erepti 5 64 IBRPP 3 ahs en ette Aes ate 5 66 IBRSC 3 saec RR ER ERR ene 5 69 NI 488 2M
3. sum sum atof buffer printf The average of the 10 readings is printf fNn sum 10 Call the ibonl function to disable the hardware and software s ibonl 0 0 void gpiberr char msg printf Ss n msg printf ibsta amp H x ibsta lt if ibsta amp ERR printf ERR if ibsta amp TIMO printf TIMO if ibsta amp END printf END if ibsta amp SRQI printf SRQI if ibsta amp ROS J printf RQS if ibsta amp CMPL printf CMPL if ibsta amp LOK printf LOK if ibsta amp REM printf REM if tbsta amp CIC printf CIC if ibsta amp ATN printf ATN if ibsta amp TACS printf TACS if ibsta amp LACS printf LACS if ibsta amp DTAS printf DTAS if ibsta amp DCAS printf DCAS printf Xn printf iberr d iberr if iberr EDVR printf EDVR lt Error gt n if iberr ECIC printf ECIC Not CIC gt n if iberr ENOL printf ENOL No Listener An if iberr printf EADR Address error gt n if iberr printf EARG Invalid argument n NI 488 2M Reference Manual 4 42 National Instruments Corp Chapter 4 if iberr ESAC print if iberr EABO print if iberr ENEB print if iberr ECAP print if iberr EFSO print if iberr EBUS print if iberr ESTB p
4. 5 NI 488 2M Reference Manual 4 26 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines SendIFC 3 SendIFC 3 Purpose Clear the GPIB interface functions with IFC Syntax void SendIFC int board board specifies a board number The GPIB Device IFC message is issued resulting in the interface functions of all connected devices returning to their cleared states This function is used as part of GPIB initialization It forces the GPIB interface board to be Controller of the GPIB and ensures that the connected devices are all unaddressed and that the interface functions of the devices are in their idle states Example Clear the interface functions of the devices connected to board 0 SendIFC 0 National Instruments Corp 4 27 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 SendList 3 SendList 3 Purpose Send data bytes to multiple GPIB devices Syntax void SendList int board Addr4882_t addresslist char data long count int eotmode board specifies a board number addresslist contains a list of primary GPIB addresses terminated by the value NOADDR The GPIB devices whose addresses are contained in the address array are addressed as Listeners the indicated board is addressed as a Talker and count data bytes contained in data are sent The count value is of type long However integer values and variables may
5. EDMA indicates that a DMA hardware error occurred during an I O operation EBTO indicates that a hardware bus timeout occurred during an I O operation This is usually the result of an attempt by a DMA Controller to access non existent memory ECAP results when a particular capability has been disabled in the driver and a call is made that attempts to make use of that capability EFSO results when an ibrdf or ibwrtf call encounters a problem performing a file operation Specifically this error indicates that the function is unable to open create seek write or close the file being accessed The specific error code for this condition is contained in ibcnt EBUS results when certain GPIB bus errors occur during device functions All device functions send command bytes to perform addressing and other bus management Devices are expected to accept these command bytes within the time limit specified by the configuration program or by ibtmo EBUS occurs if a timeout occurred during the sending of these command bytes Under normal operating circumstances the National Instruments Corp 3 15 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 remedy would be to find out which GPIB device is accepting commands abnormally slow and fix the problem with that device In situations in which slow handshaking of the commands is desirable lengthen the board time limit either with the configuration program or the ibtmo f
6. Multiline Interface Messages This appendix contains an interface message reference list which describes the mnemonics and messages that correspond to the interface functions These multiline interface messages are sent and received with ATN TRUE For more information on these messages refer to the ANSI IEEE Std 488 1978 IEEE Standard Digital Interface for Programmable Instrumentation National Instruments Corp 1 NI 488 2M Reference Manual Multiline Interface Messages Appendix A Multiline Interface Messages Hex Oct Dec ASCH Msg Hex Oct Dec ASCH Msg 00 000 0 NUL 20 040 32 SP MLAO 01 001 1 SOH GTL 21 041 33 MLA1 02 002 2 STX 22 042 34 MLA2 03 003 3 ETX 23 043 35 MLA3 04 004 4 EOT SDC 24 044 36 MLA4 05 005 5 ENQ PPC 25 045 37 MLAS 06 006 6 ACK 26 046 38 amp MLA6 07 007 7 BEL 27 047 39 i MLA7 08 010 8 BS GET 28 050 40 MLA8 09 011 9 HT TCT 29 051 41 MLA9 0A 012 10 LF 2 052 42 MLAIO 013 11 2 053 43 MLAII 0C 014 12 FF 2 054 44 MLA12 0D 015 13 CR 2D 055 45 MLAI3 016 14 SO 2E 056 46 MLAI4 OF 017 15 SI 2F 057 47 MLAIS 10 020 16 DLE 30 060 48 0 MLAI6 11 01 17 DCI LO 31 061 49 1 MLAI7 12 022 18 DC2 32 062 50 2 MLAI8 13 023 19 DC3 33 063 51 3 MLAI9 14 024 20 DC4 DCL 34 064 52 4 MLA20 15 025 21 35 065 53 5 MLA2I 16 020 22 SYN 36 066 54 6 MLA22 17 027 23 ETB 37 067 55 7 MLA23 18 030 24 CAN SPE 38 070 56 8 MLA24 19 031 25 SPD 39 071 57 9 MLA25 1 032 26
7. The HELP function gives online information about ibic and the functions available within the environment This facility provides a quick reference for checking the syntax and function of the GPIB call Using ibfind To execute any NI 488 GPIB function you must first use ibfind to open the device or board you wish to use When the device or board is opened the symbolic name of that device or board is added to the prompt If you are using NI 488 2 routines you do not need to call ibfind you may go directly to NI 488 2 mode with the SET command see below The following examples show ibfind opening dev1 Example 1 and gpib0 Example 2 Example 1 ibfind devl id 32005 dev1 Example 2 ibfind id 32005 gpibO0 The name used with the ibfind function must be a valid symbolic name known by the driver as described in ibconf refer to the ibconf section in Chapter 2 Installation and Configuration of NI 488 2M Software Both dev1 and gpib0 are default names found in the driver ibic makes no distinction between uppercase and lowercase NI 488 2M Reference Manual 6 4 National Instruments Corp Chapter 6 ibic Using ibdev To execute any GPIB function you must first use ibfind or ibdev to open and initialize an unused device The ibdev command selects an unopened device opens it and initializes its access board and the following fields to the values that are input e Primary Address e Second
8. if ibsta amp ATN printf ATN if ibsta amp TACS printf TACS if ibsta amp LACS printf LACS if ibsta amp DTAS printf DTAS if ibsta amp deor printf DCAS printf gt printf iberr d iberr if iberr EDVR printf EDVR lt Error An if iberr ECIC printf ECIC Not CIC gt n if iberr ENOL printf ENOL No Listener Mn if iberr EADR printf EADR Address error gt n if iberr printf EARG Invalid argument n if iberr ESAC printf ESAC Not Sys Ctrlr gt n if iberr EABO printf EABO Op aborted An if iberr ENEB printf ENEB No GPIB board gt n if iberr ECAP printf ECAP No capability Nn if iberr EFSO printf EFSO File sys error gt n if iberr EBUS printf EBUS Command error gt n if iberr ESTB printf ESTB Status byte lost Mn if iberr ESRQ printf ESRQ SRQ stuck on gt n if iberr ETAB printf ETAB Table Overflow gt n printf ibcnt d n ibcnt printf Xu Call the ibonl function to disable device DVM ibonl dvm 0 void dvmerr char msg char spr NI 488 2M Reference Manual 5 94 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions This routine would notify you that the DVM returned an invalid serial poll response byte printf Ss n msg
9. int Addr4882_t addresslist 3 8 9 NOADDR char messages 5 Message 0 Message 1 Message 2 Message 3 Message 4 SendSetup 0 addresslist for i 0 i lt 4 SendDataBytes 0 messages i strlen messages i NULLend SendDataBytes 0 messages 4 strlen messages 4 NLend NI 488 2M Reference Manual 4 30 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines SetRWLS 3 SetRWLS 3 Purpose Place particular devices in the Remote With Lockout State Syntax void SetRWLS int board Addr4882_t addresslist board specifies a board number The GPIB devices whose addresses are contained in the addresslist array are placed in remote mode by asserting Remote Enable REN and addressing the devices as Listeners In addition all devices are placed in Lockout State which prevents them from independently returning to local programming mode without passing through the Controller The parameter addresslist is an array of any size of address integers terminated by the value NOADDR Example Place the devices at GPIB addresses 8 and 9 in Remote With Lockout State Addr4882_t addresslist 3 8 9 NOADDR SetRWLS 0 addresslist National Instruments Corp 4 31 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 TestSRQ 3 TestSRQ 3 Purpose Determine the current state of the SRQ line Syntax
10. used to pack the primary and secondary addresses into the correct form NI 488 2M Reference Manual 4 34 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines TriggerList 3 TriggerList 3 Purpose Trigger multiple devices Syntax void TriggerList intboard Addr4882 t addresslist board specifies a board number The GPIB devices whose addresses are contained in the address array are triggered simultaneously The parameter addresslist is an array of address integers of any size terminated by the value NOADDR If the array contains only the value NOADDR or NULL the Group Execute Trigger message is sent without addressing thereby triggering all previously addressed Listeners Although the TriggerList routine is general enough to trigger any number of GPIB devices the Trigger function should be used in the common case of triggering exactly one GPIB device Example Trigger simultaneously two devices connected to board 0 whose GPIB addresses are 8 and 9 Addr4882 t addresslist 3 8 9 NOADDR TriggerList 0 addresslist National Instruments Corp 4 35 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 WaitSRQ 3 WaitSRQ 3 Purpose Wait until a device asserts Service Request Syntax void WaitSRQ int board short result board specifies a board number This routine is used to suspend execution of the program until a GPIB dev
11. A GPIB line that is used to signal either the last byte of a data message END or the parallel poll identify IDY message A 7 or 8 bit End Of String character that is sent as the last byte of a data message first in first out See GPIB The GPIB command used to trigger a device or internal function of an addressed listener See GTL General Purpose Interface Bus is the common name for the communications interface system defined in IEEE Std 488 Hewlett Packard the inventor of the bus calls it the HP IB The address of a device on the GPIB composed of a primary address MLA and MTA and perhaps a secondary address MSA The GPIB board has both a GPIB address and an I O address Reference to the National Instruments family of GPIB interface boards See GET The GPIB command used to place an addressed Listener in local front panel control mode G 4 National Instruments Corp handshake high level function ibcnt ibconf iberr ibic ibsta IEEE 488 Glossary The mechanism used to transfer bytes from the source handshake function of one device to the acceptor handshake function of another device The three GPIB lines DAV NRFD and NDAC are used in an interlocked fashion to signal the phases of the transfer so that bytes can be sent asynchronously for example without a clock at the speed of the slowest device A device function that combines several rudimentary board opera
12. In the context of this manual the transmission of commands or messages between the computer via the GPIB board and other devices on the GPIB The address of the GPIB board from the point of view of the CPU as opposed to the GPIB address of the GPIB board Also called port address or board address International Standards Organization An individual status bit of the status byte used in the parallel poll configure function See MLA Code that enables an application program cib c to call driver functions cib c is the language interface for C See MIA A GPIB device that receives data messages from a talker The GPIB command used to tell all devices that they may or should ignore remote GPIB data messages or local front panel controls depending on whether the device is in local or remote program mode National Instruments Corp low level function M MB MLA or my last address MSA or my secondary address MTA or my talk address N NDAC or not data accepted NRFD or not ready for data opened device or board Glossary A rudimentary board or device function that performs a single operation See high level function Megabytes of memory The GPIB command used to address a device to bealistener There are 31 of these primary addresses The GPIB command used to address a device to be a listener or a talker when extended two byte addressing is used The complete address is an M
13. printf Status Byte x n spr Call the ibonl function to disable device DVM ibonl dvm 0 National Instruments Corp 5 95 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 Example Program Board Functions include lt stdio h gt include ugpib h Application program variables passed to GPIB functions char rd 512 read data buffer int bd board or device number void dvmerr char msg char code device error function void gpiberr char msg GPIB error function main system clear printf READ MEASUREMENT FROM FLUKE 45 n print Assign an unique identifier to board 0 and store in variable bd if bd ibfind 0 lt 0 gpiberr ibfind Error exit 1 Send the Interface Clear IFC message to all devices if ibsic bd amp ERR gpiberr ibsic Error exit 1 Turn the Remote Enable REN signal if ibsre bd 1 amp ERR gpiberr ibsre Error exit 1 Inhibit front panel control with the Local Lockout LLO command place the Fluke 45 in remote mode by addressing it to listen send the Device Clear DCL message to clear internal device functions and address the GPIB board to talk bd 021 024 4L if ibsta amp ERR gpiberr ibcmd Error exit 1 NI 488 2M Reference Manual 5 96 Nat
14. 1 Swap pairs of bytes during write Default zero IbcSPollTime 0 0018 0 to 17 Sets the length of time the driver waits for a serial poll response byte when polling the given device The length of time represented by 0 to 17 corresponds to the ibtmo values Default 11 IbcEndBitIsNormal 0 001 zero Do not set the END bit of ibsta when an EOS match occurs during a read non zero Set the END bit of ibsta when an EOS match occurs during a read Default non zero IbcUnAddr Ox001B zero Do not send Untalk UNT and Unlisten UNL at the end of device level reads and writes non zero Send UNT and UNL at the end of device level reads and writes Default zero National Instruments Corp 5 35 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBDEV 3 IBDEV 3 Purpose Open and initialize an unused device when the device name is unknown Syntax ud int ibdev int boardindex int pad int sad int tmo int eot inteos boardindex is an index from 0 to number of boards 1 of the access board that the device descriptor must be associated with The arguments pad sad tmo eot and eos dynamically set the software configuration for the NI 488 I O functions These arguments configure the primary address secondary address I O timeout asserting EOI on last byte of data sourced and the End Of String mode and byte respectively Refer to IBPAD
15. 6 12 SendList 6 12 SendLLO 6 12 SendSetup 6 12 SetRWLS 6 12 TestSRQ 6 12 TestSys 6 12 Trigger 6 12 TriggerList 6 12 WaitSRQ 6 12 sample programs 6 20 to 6 25 set 6 3 6 8 to 6 9 turn off display 6 18 turn on display 6 18 ibist 5 6 5 47 6 10 iblines 5 6 5 48 to 5 49 6 10 ibllo 5 50 ibln 3 12 5 6 5 51 to 5 52 6 10 ibloc 3 9 5 6 5 53 to 5 54 6 10 ibonl 3 11 3 13 5 6 5 55 to 5 56 6 10 ibpad 3 14 5 6 5 57 to 5 58 6 10 ibpct 5 6 5 59 6 11 ibppc 3 14 5 6 5 60 to 5 61 6 11 ibrd 2 9 3 3 3 14 5 5 5 6 5 62 to 5 63 6 7 6 9 6 11 ibrdf 3 15 5 6 5 64 to 5 65 6 11 ibrpp 3 12 5 6 5 66 to 5 68 6 11 ibrsc 3 14 5 6 5 69 6 11 ibrsp 2 11 3 2r 16 5 3 5 6 5 70 to 5 71 6 11 ibrsv 5 6 5 72 6 1 ibsad 3 13 5 6 5 DoS 74 6 11 ibsgnl 2 13 3 18 5 75 to 5 76 ibsic 3 9 3 13 3 14 5 6 5 77 6 11 ibsre 3 14 5 6 5 78 6 11 National Instruments Corp Index 9 NI 488 2M Reference Manual Index ibsta 3 6 3 6 to 3 11 3 13 ATN 3 7 3 9 CIC 3 7 3 9 3 11 CMPL 3 7 3 9 DCAS 3 7 3 10 3 11 DTAS 3 7 3 10 3 11 END 3 7 3 8 3 11 ERR 3 7 3 8 3 11 in ibic 6 1 6 12 6 14 to 6 15 LACS 3 7 3 10 3 11 LOK 3 7 3 9 3 11 REM 3 7 3 9 3 11 RQS 3 7 3 8 to 3 9 SRQI 3 7 3 8 to 3 9 TACS 3 7 3 10 3 11 TIMO 3 7 3 8 ibtmo 3 14 3 15 3 16 4 5 5 6 5 79 to 5 81 6 11 ibtrg 5 6 5 82 6 11 ibwait 2 9 3 8 3 9 3 10 3 13 3 1
16. Enable operations from the front panel of a device Syntax void EnableLocal intboard Addr4882 t addresslist board specifies a board number The GPIB devices whose addresses are contained in the addresslist array are placed in local mode by addressing the devices as Listeners and sending the GPIB Go To Local command The parameter addresslist is an array for any size of address integers terminated by the value NOADDR If the array contains only the value NOADDR or NULL Remote Enable REN becomes unasserted immediately placing all GPIB devices in local mode Example Place the devices at GPIB addresses 8 and 9 in local mode Addr4882 t addresslist 3 8 9 NOADDR EnableLocal 0 addresslist National Instruments Corp 4 11 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 EnableRemote 3 EnableRemote 3 Purpose Enable remote GPIB programming of devices Syntax void EnableRemote intboard Addr4882 t addresslist board specifies a board number The GPIB devices whose addresses are contained in the addresslist array are placed in remote mode by asserting Remote Enable REN and addressing the devices as Listeners The parameter addresslist is an array for any size of address integers terminated by the value NOADDR If the array contains only the value NOADDR or NULL for addresslist no addressing is performed and Remote Enable REN becomes asserted
17. NI 488 function with examples in C The descriptions are listed alphabetically for easy reference To the right of each function notice a number in parentheses This number is UNIX convention It identifies the type of function and also refers you to a particular section in your UNIX Reference Pages NI 488 2M Reference Manual 5 10 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBASK 3 IBASK 3 Purpose Return information about software configuration parameters Syntax int ibask intud int option int value Note This function may not be available in all versions of NI 488 2M device drivers ud designates a board or device unit descriptor option selects the configuration item for which you want to return the value value is the current value of the selected configuration item ibask returns the current value of various configuration parameters for the board or device The current value of the selected configuration item is returned in the integer pointed to by value Tables 5 2 and 5 3 list the valid configuration parameter options for ibask An EARG error results if option is not a valid configuration parameter An ECAP error results if option does not work with the driver If ud is invalid or the NI 488 2M driver is not installed an EDVR error results Device Function Example Find out the current access bus of device dev1 int bus ibask devl1 IbaBNA amp bus B
18. dmm ibdev 0 1 0 12 1 0 ibclr dmm National Instruments Corp 5 7 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 Step 3 Configuring the Device After the ibfind and ibclr functions the instrument is ready to receive commands To configure the multimeter device specific commands are sent using the ibwrt function The first argument of the ibwrt function is the unit descriptor for the meter returned in the variable dmm by the ibfind function ibwrt dmm F1ROS2T4 8 The ibwrt function sends the bytes F1ROS2T4 to the meter The bytes sent to an instrument are different for most instruments The command bytes for your instrument can be found in its user manual The bytes in this example configure the voltage type F1 voltage range RO update speed S2 and the trigger mode T4 of the meter Step 4 Triggering the Device Previously the device was set to wait for a trigger before sending a measurement reading You must first send a trigger command to the device before reading the measurement value ibtrg dmm Step 5 Taking Measurements Once the meter is configured it can take a measurement and display it on its front panel To read the measurement over the GPIB the ibrd function is used Again the first argument is the unit descriptor for the meter The variable rd holds the measurement value upon completion of the function The meter sends 13 bytes of da
19. ibic Chapter 6 11 list isa comma separated list of address integers optionally enclosed in parentheses An empty list can be expressed by empty parentheses 12 mode is a termination mode mnemonic or integer Mnemonics are NLend NULLend for Send type operations and STOPend for Receive type operations 13 address isan integer representing a GPIB address If only a primary GPIB address is required simply enter that integer If a secondary address is also required create an integer with the primary address in the low order byte and the secondary address in the high order byte for example pad 3 and sad 61 could be expressed as 0x6103 14 line and sense are integers representing the data line to respond on and the sense of the response Status Word ibic functions return the status word ibsta in two forms a hex value in square brackets and a list of mnemonics in parentheses A sample call follows dev1 ibwrt f2t3x 900 rqs cmpl COUNT 5 dev1 In this example the status word shows that the device function write operation completed successfully and that dev1 is requesting service Table 6 3 lists the mnemonics of the status word This is the same list that is given in Table 3 1 NI 488 2M Reference Manual 6 14 National Instruments Corp Chapter 6 ibic Table 6 3 Status Word Layout Description dev Device requesting service
20. must be large enough to accommodate all expected listening devices because no check is made for overflow of the array Because most GPIB devices have the ability to listen this routine is normally used to detect the presence of devices at particular addresses Once detected they usually can be interrogated by identification messages to determine what devices they are Example Determine which one of the devices at addresses 8 9 and 10 are present on the GPIB Addr4882_t addresslist 4 8 9 10 NOADDR Addr4882 t resultlist 5 FindLstn 0 addresslist resultlist 5 National Instruments Corp 4 13 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 FindRQS 3 FindRQS 3 Purpose Determine which device is requesting service Syntax void FindRQS int board Addr4882 t addresslist short result board specifies a board number addresslist contains a list of primary GPIB addresses terminated by the value NOADDR Starting from the beginning of the addresslist the indicated devices are serial polled until one is found which is asserting SRQ The status byte for this device is returned in the variable result In addition the index of the device s address in addresslist is returned in the global variable ibcnt If none of the specified devices is requesting service the error code ETAB is returned in iberr and ibcnt contains the index of the NOADDR entry of the list
21. void Test SRQ int board short result board specifies a board number This call places the value 1 in the variable result if the GPIB SRQ line is asserted Otherwise it places the value of 0 into result This routine is similar in format to the Wait SRQ routine except that WaitSRO suspends itself waiting for an occurrence of SRQ whereas TestSRQ returns immediately with the current SRQ state Example Determine the current state of SRQ short result TestSRO 0 amp result if result 1 SRQ is asserted else No SRO at this time NI 488 2M Reference Manual 4 32 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines TestSys 3 TestSys 3 Purpose Cause devices to conduct self tests Syntax void TestSys int board Addr4882 t addresslist short resultlist board specifies a board number The GPIB devices whose addresses are contained in the address array are simultaneously sent a message that instructs them to conduct their self test procedures Each device returns an integer code signifying the results of its tests and these codes are placed into the corresponding elements of the resultlist array The IEEE 488 2 standard specifies that a result code of 0 indicates that the device passed its tests and any other value indicates that the tests resulted in an error The variable ibcnt contains the number of devices that failed their tests The parameter
22. 25 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 SendDataBytes 3 SendDataBytes 3 Purpose Send data bytes to already addressed devices Syntax void SendDataBytes int board char data long count int eotmode board specifies a board number data contains data bytes to be sent on to the GPIB The number of bytes to be sent from the string is indicated by the argument count The count value is of type long Even though it is a long value in these languages however integer values and variables may also be passed eotmode is a flag used to describe the method of signaling the end of the data to the Listeners It should be set to one of the following constants NLend Send NL linefeed with EOI after the data bytes DABend Send EOI with the last data byte in the string NULLend Do nothing to mark the end of the transfer These constants are defined in the header file ugpib h SendDataBytes assumes that all GPIB Listeners have already been addressed by a prior call to functions such as SendSetup Send or SendCmds Thus it is used specifically to skip the addressing step of GPIB management The Send routine is normally used to accomplish the entire sequence of addressing followed by the transmission of data bytes Example Send an identification query to all addressed Listeners The transmission should be terminated with a linefeed character with END SendDataBytes 0 IDN
23. 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBWAIT 3 continued IBWAIT 3 Table 5 10 Wait Mask Layout Continued B Hex Mnemonic Position Value Description it 3 2 1 al ARR s 0 8 GPIB board is Talker GPIB board is Listener GPIB board is in device trigger state GPIB board is in device clear state ibwait also updates ibsta If mask 0 or mask hex 8000 the ERR bit the function returns immediately If the TIMO bit is zero or the time limit is set to zero with the ibtmo function timeouts are disabled Disabling timeouts should be done only when setting mask 0 or when it is certain the selected event will occur otherwise the processor may wait indefinitely for the event to occur Device IBWAIT Function If ud specifies a device only the ERR TIMO END RQS and CMPL bits of the wait mask and status word are applicable If automatic polling is enabled then on an ibwait for RQS each time the GPIB SRQ line is asserted the access board of the specified device serial polls all devices on its GPIB and saves the responses until the status byte returned by the device being waited for indicates that it was the device requesting service bit hex 40 is set in the status byte If the TIMO bit is set ibwait returns if the event does not occur within the timeout period of the device Board IBWAIT Function If ud specifies a board all bits of the wait mask and st
24. 2M Software Reference Manual Edition Date February 1996 Part Number 370963A 01 Please comment on the completeness clarity and organization of the manual continues If you find errors in the manual please record the page numbers and describe the errors Thank you for your help Name Title Company Address Phone Mail to Technical Publications National Instruments Corporation 6504 Bridge Point Parkway Austin TX 78730 5039 Fax to Technical Publications National Instruments Corporation 512 794 5678 Glossary m A AC acceptor handshake access board ANSI ASCII ATN or attention automatic serial polling alternating current A GPIB interface function that receives data or commands Listeners use this function to receive data and all devices use it to receive commands See source handshake and handshake The GPIB board that controls and communicates with the devices on the bus that are attached to it American National Standards Institute American Standard Code for Information Interchange A GPIB line that distinguishes between commands and data messages When ATN is asserted bytes on the GPIB DIO lines are commands A feature of the NI 488M software in which serial polls are executed automatically by the driver whenever a device asserts the GPIB SRQ line N
25. 3 isdem 4 20 Receive pie e nere Pere ce 4 2 Rec iveSetup 3 coo deme fet ee eh tere 4 22 ResetSys icta ade trtum ONG ER ES e Ede dvs cy 4 23 Send 3 4 ans etre IG RR RON 4 24 SendCinds 3 uL hha ie nenne red ir 4 25 sendDataBytes 3 atate RP eR 4 26 SendIPC aei S ER RR te RR A IURE 4 27 ante tei 4 28 SendL 3 ote etit eee tiet ine teet ees 4 29 SendSetup ee ere ee eie 4 30 SetRWIS Co D EEE t en aiii e RT 4 31 TestSRQ PR 4 32 515 5 3 4 33 Trugser 3 5 ales aes hah e noD eec 4 34 TrggerList 3 eco te detti nt 4 35 W aitSRO 3 dert EPIS GUI BERG 4 36 C GPIB Programming Example see 4 37 C Example Program NI 488 2 Routines 4 39 National Instruments Corp vii NI 488 2M Reference Manual Contents Chapter 5 NI 488M Software Characteristics and Functions 5 1 General Programming Information sees 5 1 DEVICE Functions epe ner REI 5 1 Automatic Serial Polling sese 5 2 Compatbility 5 AURI 5 4 Internal Handler Operation sees 5 4 C NI 488 I O Calls and Functions 5 5 Writing an NI 488 Program 5 7 Step 1 Initializing the System
26. 488M Software Characteristics and Functions Chapter 5 IBSGNL 3 continued IBSGNL 3 You must arrange for the signal to be caught or your program will terminate when the signal is sent An ibsgnl call remains in effect until an ibonl call an ibsgnl of 0 or the program terminates Example Establish srqservice as the function to call for SRQ servicing int dvm void far srqservice ine Sp ibrsp dvm amp spr Signal SIGINT srqservice analyze the response here main int 9 0 ibfind gpib0 disable autopolling ibconfig 9 0 IbcAUTOPOLL 0 ibsgnl gpib0 SROI Signal SIGINT srqservice See also SIGNAL and IBWAIT NI 488 2M Reference Manual 5 76 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBSIC 3 IBSIC 3 Purpose Send interface clear for 100 us Syntax int ibsic intud int v ud specifies an interface board v specifies how IFC is sent ibsic must be used at the beginning of a program if board functions are used If v equals 1 the ibsic function asserts the IFC signal for at least 100 us if the GPIB board is System Controller This action initializes the GPIB makes the interface board CIC and Active Controller with ATN asserted and is generally used when a bus fault condition is suspected Some non standard devices may require a pulse of IFC longer than 100 us If you have one of these dev
27. 6 15 Byte Count eie detecte ebbe 6 16 Auxiliary Functions 2 noeh eter eet 6 16 HELP Display Help Information see 6 17 Repeat Previous Function esee 6 17 Turn OFF Display nette mein tees 6 18 Turn ON Display epe 6 18 n Repeat Function n Times eene 6 19 Execute Indirect File cccccccsccssesecessesscescesscesseceeeseeeeeees 6 19 PRINT Display the ASCII String ene 6 20 National Instruments Corp ix NI 488 2M Reference Manual Contents Eor Q exit r eon nee tis 6 20 ibi Sample Programs secrete pe RR Ice tiere 6 20 NI 488 2 Routmes 2 eese eer eee 6 20 Device E nctlons 3 2 merece ee tende 6 22 Board Futons deed eed 6 23 Appendix A Multiline Interface Messages A 1 Appendix B Common Errors and Their Solutions B 1 Appendix C Redirection to the GPIB 7 ss 1 Appendix Operation of the GPIB 1 sse D 1 Appendix E Customer Communication sse 1 oun 6 1 Index he a Index 1 NI 488 2M Reference Manual x National Instruments Corp Figure Figure Figure Figure Figure Figure Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Ta
28. 8 auto serial polling 2 5 2 12 change characteristics 2 6 DMA mode 2 13 END message 2 8 EOL 2 5 EOS 2 5 explanation of field 2 7 GPIB bus timing 2 12 help 2 7 high speed timing 2 5 primary GPIB address 2 9 reset value 2 7 return to map 2 7 secondary GPIB address 2 9 set EOI with EOS on write 2 11 set EOI with last byte of write 2 11 system controller 2 5 2 7 2 12 terminate READ on EOS 2 11 time limit on I O and wait function calls 2 8 timeout settings 2 5 type of compare on EOS 2 11 UNIX signal 2 5 2 13 upper level device map for board GPIBx 2 3 to 2 5 connecting a device 2 4 device maps 2 4 disconnecting a device 2 4 editing board or device characteristics 2 5 examining board or device characteristics 2 4 exiting 2 5 help 2 4 renaming a device 2 4 ibconfig 5 5 5 26 to 5 35 NI 488 2M Reference Manual Index 6 National Instruments Corp Index ibdev 3 4 5 4 5 5 5 36 to 5 37 6 5 to 6 7 6 10 ibdma 5 5 5 38 6 10 ibeos 3 14 5 5 5 39 to 5 41 6 10 ibeot 5 5 5 42 to 5 43 6 10 iberr 3 6 3 8 3 11 to 3 16 6 1 6 9 EABO 3 11 3 14 to 3 15 EADR 3 11 3 14 EARG 3 11 3 14 EBTO 3 11 3 15 EBUS 3 12 3 15 to 3 16 ECAP 3 12 3 15 ECIC 3 11 3 12 to 3 13 EDMA 3 1 3 15 EDVR 3 11 3 12 EFSO 3 12 3 15 ENEB 3 11 3 15 ENOL 3 11 3 13 ESAC 3 11 3 14 ESRQ 3 12 3 16 ESTB 3 12 3 16 ETAB 3 12 3 16 ibfind 3 4 3 12 5 4 5 5 5 44 to 5 45 6 4 6 10 ibgts
29. Acallto ibonl affects bits other than those listed here according to the rules explained above In the event that a function call returns an ENEB or EDVR error all status word bits except the ERR bit are cleared because these error codes indicate that it is not possible to obtain the status of the GPIB board Error Variable iberr If the ERR bit is set in the status word a GPIB error has occurred that is if the previous GPIB call returned with an ibsta value in which the ERR bit is set the following interpretations of iberr apply The error code is returned in the variable iberr Table 3 2 lists these error codes Table 3 2 GPIB Error Codes Se Mnemonic Value Explanation o UNIX eror coden ioon O EARG Invalid argument to function call ESAC GPIB board not System Controller as required EABO 6 T O operation aborted timeout ENEB Non existent GPIB board EDMA 8 DMA hardware problem EBTO 9 DMA hardware bus timeout continues National Instruments Corp 3 11 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 Table 3 2 GPIB Error Codes Continued Suggested Decimal Mnemonic Value Explanation ECAP No capability for operation A description of each error and some conditions under which each error may occur follows EDVR 0 EDVR is returned when the device or board name passed in an ibfind call is not configured in the driver ibcnt will contain the UNIX
30. All Listeners protocol for loop 0 loop lt instruments loop 30 loopt loop instruments 31 NOADDR Mark the end of the array Find all of the listeners on the bus x printf Finding all listeners on the bus Mn National Instruments Corp 4 39 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 FindLstn 0 instruments result 31 if ibsta amp ERR gpiberr FindLstn Error exit 1 num_listeners ibcnt 1 printf Number of instruments found d n num listeners Now send the IDN command to each of the devices that you found The GPIB board is at address 0 by default Your GPIB board does not respond to IDN so skip it x for loop 1 loop lt num listeners 1 Send 0 result loop IDN 5L NLend if ibsta amp ERR gpiberr Send Error exit 1 Receive 0 result loop buffer 101 STOPend if ibsta amp ERR gpiberr Receive Error exit Ly buffer ibcnt 0 printf The instrument at address d is a s n GetPAD result loop buffer if strncmp buffer FLUKE 45 9 0 fluke result loop printf We found the Fluke n break if loop gt num_listeners printf Did not find the Fluke n exit 1 Reset the Fluke DevClear 0 fluke if ibsta amp ERR gpiberr DevClear Error exit 1 Send 0 f
31. Board Reference Numbers eene 2 1 TDG OME 2 2 Upper and Lower Levels of ibconf 2 2 Upper Level Device Map for Board GPIBX 2 3 Device Maps of the Boards sees 2 4 lon 2 4 2 4 DIS COTTE CE 2 4 Bit ode ottima e heiter 2 5 Is EE 2 5 Lower Level Device Board Characteristics 2 5 Change Characteristics 2 6 Help ERO RERO eer vn 2 7 1 eer Uere thee 2 7 Reset Value sre rere eer 2 7 Ret rn t Reihen oer 2 7 Default Configurations eeeseeeeeeeeenen enne 2 7 Default Values eR netten dee e RE 2 8 Device and Board Characteristics eese 2 8 Primary GPIB Address eere 2 9 Secondary GPIB Address esee 2 9 National Instruments Corp v NI 488 2M Reference Manual Contents Timeout Settings issos esei eee ee beet 2 9 EOS byte eee rere ED ERR REAL 2 10 Terminate READ on EOS eee 2 11 Set EOI with EOS on Write wo ee 2 11 Type of Compare on EOS sse 2 11 Set EOI with Last Byte of Write sess 2 11 Board Is System Contro
32. Corp 3 19 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 The next two chapters describe in detail the NI 488 2 routines and NI 488 functions respectively Complete descriptions of each routine and function are given and example code and programs are shown NI 488 2M Reference Manual 3 20 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines This chapter contains a discussion of the important characteristics of the NI 488 2 routines available in the driver that are common to all programming languages It also describes the calling syntax for the procedures in C Overview The IEEE 488 2 1992 specification explains in greater detail than the earlier IEEE 488 1 specification the exact ways in which the GPIB is to be managed by the Controller the standard messages that compliant devices should understand the mechanisms by which device errors and other status information are to be reported and various protocols aimed at discovering what compliant devices are connected to the bus and configuring these devices To be fully compliant with the IEEE 488 2 protocol the latest revisions of many National Instruments GPIB interface boards are now fully compatible with the more stringent requirements of the IEEE 488 2 specification In addition routines have been added to the driver By using these routines you can have a programming interface that closely resembles the descript
33. DTAS printf DTAS if ibsta amp DCAS printf DCAS pring printf iberr d iberr if iberr EDVR printf EDVR lt Error gt n if iberr ECIC printf ECIC lt Not CIC gt n if iberr ENOL printf ENOL No Listener gt n if iberr printf EADR Address error gt n if iberr EARG printf EARG Invalid argument gt n if iberr ESAC printf ESAC lt Not Sys Ctrlr gt n if iberr EABO printf EABO Op aborted gt n if iberr ENEB printf ENEB No GPIB board gt n if iberr ECAP printf ECAP No capability gt n if iberr EFSO printf EFSO File sys error gt n if iberr EBUS printf EBUS Command error gt n if iberr ESTB printf ESTB Status byte lost gt n if iberr ESRQ printf ESRQ SRQ stuck on gt n if iberr ETAB printf ETAB Table Overflow gt n printf ibcnt d n ibcnt printf n Call the ibonl function to disable the hardware and software ibonl bd 0 void dvmerr char msg char code This routine would notify you that the DVM returned an invalid serial poll response byte printf Ss n msg printf Status byte x n code 0 Call the ibonl function to disable the hardware and software ibonl bd 0 National Instruments Corp 5 99 NI 488 2M Reference Manual Chapter 6 ibic With t
34. Hello Execute Indirect File In the function an indirect file is a text file that contains ibic functions It is similar to an batch file and is created the same way reads the specified indirect file and executes the ibic functions in sequence as if they were entered in that order from the keyboard For example entering gpib0 usrfile executes the ibic functions listed in the file usr file and entering gpibO 3 usrfile repeats that operation three times The display mode in effect before this function was executed is restored afterward but may be changed by functions in the indirect file National Instruments Corp 6 19 NI 488 2M Reference Manual ibic Chapter 6 PRINT Display the ASCII String The PRINT function can be used to echo a string to the screen Example devi print hello hello devi print and r n x67 x6f x64 x62 x79 x65 and goodbye PRINT can be used to display comments from indirect files The print strings will appear even if the display is suppressed with the function The second PRINT example illustrates the use of hex values in ibic strings E or Q exit or quit The exit command or the ibic function E or Q returns you to the operating system ibic Sample Programs Refer to Chapter 4 NI 488 2M Software Characteristics and Routines and Chapter 5 NI 488M Software Characteristics and Functions for a description of the programming steps that may be u
35. IBPPC 3 IBPPC 3 Purpose Parallel Poll Configure Syntax int ibppc intud int v ud specifies a device or an interface board v must be either a valid parallel poll enable disable command or zero ibppc returns the previous value of v in iberr if an error does not occur Device IBPPC Function If ud specifies a device the ibppc function enables or disables the device from responding to parallel polls ibppc calls the board ibcmd function to send the following commands e Talk address of the access board e Unlisten e Listen address of the device e Secondary address of the device if applicable e Parallel Poll Configure PPC e Parallel Poll Enable PPE or Disable PPD Other command bytes are sent if necessary Each of the 16 PPE messages specifies the GPIB data line DIO1 through DIOS and sense one or zero that the device must use when responding to a parallel poll The assigned message is interpreted by the device along with the current value of the individual status ist bit to determine if the selected line is driven true or false For example if the PPE hex 64 DIOS is driven true if ist 0 and false if ist 1 and if PPE hex 68 DIO1 is driven true if ist 1 and false if ist 0 Any PPD message or zero value cancels the PPE message in effect You must know which PPE and PPD messages are sent and determine what the responses indicate NI 488 2M Reference Manual 5 60 National Instruments Corp Chapter 5 NI
36. IBSAD IBTMO IBEOT and IBEOS for more information on each argument The device descriptor is returned in the variable ud The ibdev command selects an unopened device opens it and initializes it You can use this function in place of ibfind ibdev returns a device descriptor of the first unopened user configurable device that it finds For this reason it is very important to use ibdev only after all of your ibfind calls have been made This is the only way to ensure that ibdev does not use a device that you plan to use via an ibfind call The ibdev function performs the equivalent of the ibonl function to open the device Note The device descriptor of the NI 488 2M driver can remain open across invocations of an application so be sure to return the device descriptor to the pool of available devices by calling ibonl with v 0 when you are finished using the device If you do not that device will not be available for the next ibdev call If the ibdev call fails a negative number is returned in place of the device descriptor There are two distinct errors that can occur with the ibdev call e fno device is available or the specified board index refers to non existent board it returns the EDVR or ENEB error e If one of the last five parameters is an illegal value it returns with a good board descriptor and the EARG error NI 488 2M Reference Manual 5 36 National Instruments Corp Chapter 5 NI 488M Software Characterist
37. Reference Manual viii National Instruments Corp Contents IBRSP 3 5 70 IBRSV 3 cierre teo e p alae 5 72 IBSAD 3 5 etae np eR 5 73 IBSGNIE 3 depot epit epe 5 75 IBSIC hia kat eee mee 5 77 IBSRE 3 5 eee EE ER 5 78 IBIMO Sani 5 79 IBTRG 3 iaa emeret 5 82 IB WAIT 8 attri tete re 5 83 IBWRT 3 rane PEE pre 5 86 IBWRTE UR URDU 5 88 C GPIB Programming Examples esee 5 90 C Example Program Device Functions 5 92 C Example Program Board Functions 5 96 6 o ce Gace nac Sd t meee Aaa eR 6 1 iiio eves opens ep e qve teg dh sees 6 1 Using NI 488 2 Routines seen 6 2 Using Send RENE eite 6 3 Using i eere eee ie O 6 3 Using NI 488 Functions essere 6 3 Using HELP a RAN dieci 6 4 Usingabfind medo E 6 4 Usingabdev iiec eee EH 6 5 Using ibwizt cie ence te 6 7 6 7 How to ette rre eg 6 8 Adding Common EOS Characters sees 6 8 Using SET i noe erm DEP Dei tees 6 8 ibic Functions and Syntax oe eee ce eeeeeeeeeeeeesaececeeeeseeeeseneeaees 6 9 Status dear erect edens 6 14 Error Code Luise recie ee tet
38. a device with both a primary and a secondary address the two addresses are packed into an integer with the primary address in the lower byte and the secondary address in the higher byte In C such integers would resemble for example 6103 which indicates a device whose primary address is 3 and whose secondary address is hex 61 Routines that operate on multiple devices have as their second parameter an integer array containing the addresses in question The individual addresses are formed in the same way as described in the previous paragraph for the single device routines except that they are placed in National Instruments Corp 4 3 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 consecutive elements of an integer array followed by a special value NOADDR to mark the end of the addresses I O routines contain a buffer argument and in some languages a count argument If present the count argument may be specified as either an integer or a long integer if allowed by the language Some routines require other parameters to fulfill particular specialized needs of the routine Relationship of NI 488 2 Routines to NI 488 Calls The NI 488 2 routines have a complete set of Controller procedures and protocols as defined in IEEE 488 2 There are cases however where more detailed control of the GPIB is required in ways that are outside the scope of the IEEE 488 2 standard These situations i
39. also be passed eotmode isa flag used to describe the method of signaling the end of the data to the Listener It should be set to one of the following constants NLend Send NL linefeed with EOI after the data bytes DABend Send EOI with the last data byte in the string NULLend Do nothing to mark the end of the transfer These constants are defined in the header file ugpib h This routine is similar to Send except that multiple Listeners are able to receive the data with only one transmission Example Send an identification query to the GPIB devices at address 8 and 9 The transmission should be terminated using a linefeed character with EOI Addr4882 t addresslist 3 8 9 NOADDR SendList 0 addresslist IDN 5 NLend NI 488 2M Reference Manual 4 28 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines SendLLO 3 SendLLO 3 Purpose Send the Local Lockout message to all devices Syntax void SendLLO int board board specifies a board number The GPIB Local Lockout message is sent to all devices so that the devices cannot independently choose the local or remote states While Local Lockout is in effect only the Controller can alter the local or remote state of the devices by sending appropriate GPIB messages SendLLO is reserved for use in unusual local remote situations particularly those in which all devices are to be locked into local programming state
40. at talk address hex 4C ASCII L the listen address of the board is hex 20 or ASCII lt space gt int brd0 char rd 100 brd0 ibfind gpib0 open board ibemd brd0 L 3 UNL TAD MLA ibrd rd 100 2 terminate the read on an EOS character see the BEOS Board Function Example National Instruments Corp 5 63 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBRDF 3 IBRDF 3 Purpose Read data from GPIB into file Syntax int ibrdf intud char flname ud specifies a device an interface board 1 is the filename under which the data is stored 1name specifies null terminated UNIX pathname ibrdf automatically opens the file If the file does not exist ibrdf creates it On exit ibrdf closes the file An EFSO error results if it is not possible to open create seek write or close the specified file The ibrdf function terminates on any of the following events Anerror is detected e time limit is exceeded e END message is detected e An EOS character is detected if this option is enabled e Device Clear DCL or Selected Device Clear SDC command is received from another device which 15 the CIC After termination ibcnt is the number of bytes read When the device ibrdf function returns ibsta holds the latest device status ibcnt is the number of bytes read and if the ERR bit in
41. characteristic is no Set EOI with EOS on Write A yes response to this field causes the GPIB board to assert the EOI line when the EOS byte is detected on a write operation The default option for this characteristic is no Type of Compare on EOS This field specifies the type of comparison to be made with the EOS byte You may indicate whether all eight bits are to be compared or just the seven least significant bits ASCII or ISO format This field is only valid if a yes response was given for either the Set EOI with EOS on Write field or the Terminate Read on EOS field The default option for this characteristic is 7 bit Set EOI with Last Byte of Write Some devices as Listeners require that the Talker terminate a data message by asserting the EOI line with the last byte A yes response causes the GPIB interface board to assert the EOI line on the last data byte The default option for this characteristic is yes National Instruments Corp 2 11 NI 488 2M Reference Manual Installation and Configuration of NI 488 2M Software Chapter 2 Board Is System Controller Board Characteristic Only This field appears on the board characteristics screen only The System Controller in a GPIB system is the device that maintains ultimate control over the bus There should be at most one device designated System Controller in any GPIB system In some situations such as a network of computers linked by the GPIB interface board another devi
42. cnt National Instruments Corp 5 43 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBFIND IBFIND Purpose Open device and return the unit descriptor associated with the given name Syntax int ibfind char udname udname is a string containing a default or configured device or board name ud is a variable containing the unit descriptor returned by ibfind ibfind returns a number that is used in each function to identify the particular device or board that is used for that function Calling ibfind is required to associate a variable name in the application program with a particular device or board name The name used in the udname argument must match the default or configured device or board name The number referred to throughout this manual as a unit descriptor is returned here in the variable ud Note For board calls the unit descriptor may be substituted with an integer board index of zero 0 or one 1 This feature allows any of the NI 488 board functions to be used compatibly with the NI 488 2 procedures described in Chapter 4 NI 488 2M Software Characteristics and Routines ibfind performs the equivalent of ibonl to open the specified device or board and to initialize software parameters to their default configuration settings Use a variable name close to the actual name of the device or board to simplify programming effort The unit descriptor is valid until ibonl is use
43. error code The remedy is to replace the argument to ibfind with a valid board or device name or to reconfigure the driver using the ibconf utility to recognize the name EDVR is also returned when an invalid unit descriptor is passed to any function call The remedy is to be sure that ibfind has been called and that it completed successfully Also note that following a call to 1bonl with a second argument of 0 which places brd offline an ibfind is required before any subsequent calls to or using that device or board EDVR is also returned when the driver is not installed The remedy is to verify that the software was installed correctly ECIC 1 ECIC is returned when one of the following board functions or routines is made while the board is not CIC e Any of the NI 488 2 routines e board functions that put command bytes on the GPIB bus ibln ibrpp NI 488 2M Reference Manual 3 12 National Instruments Corp Chapter 3 ENOL 2 Understanding the NI 488 2M Software ibcac ibgts e device functions that affect the GPIB In cases when the GPIB board should always be the CIC the remedy is to be sure to call SendIFC or ibsic to send Interface Clear before attempting any of these calls and to avoid sending the command byte TCT hex 09 Take Control In multiple CIC situations the remedy is to always be certain that the CIC bit appears in the status word ibsta before attempting these calls If i
44. example one device may always be a Talker called a Talk only device and there may be one or more Listen only devices A Controller is necessary when the active or addressed Talker or Listener must be changed The Controller function is usually handled by a computer With the GPIB interface board and its software your personal computer plays all three roles e Controller to manage the GPIB e Talker to send data e istener to receive data The Controller In Charge and System Controller Although there can be multiple Controllers on the GPIB only one Controller at a time is active or Controller In Charge CIC Active control can be passed from the current CIC to an idle Controller Only one device on the bus the System Controller can make itself the CIC The GPIB interface board is usually the System Controller NI 488 2M Reference Manual D 2 National Instruments Corp Appendix Operation of the GPIB GPIB Signals and Lines The interface system consists of 16 signal lines and 8 ground return or shield drain lines The 16 signal lines are divided into the following three groups e Eight data lines e Three handshake lines e Five interface management lines Data Lines The eight data lines DIO1 through DIO8 carry both data and command messages All commands and most data use the 7 bit ASCII or ISO code set in which case the eighth bit DIO8 is unused or used for parity Handshake Lines Three lines as
45. ibconf National Instruments Corp 2 1 NI 488 2M Reference Manual Installation and Configuration of NI 488 2M Software Chapter 2 On some systems ibconf will show you the relationship between the board number and the base address of the board thereby identifying the board by its base address On other systems the relationship might be described in terms of other settings such as board slot number or SCSI small computer system interface ID It may be necessary for you to look at system specific configuration files to determine the relationship Refer to the Getting Started manual included with your NI 488 2M driver software for configuration information specific to your system Continue to the next section ibconf for information on ibconf ibconf ibconf is a screen oriented interactive program It is largely self explanatory with help screens to explain all commands and options When used interactively ibconf reads in the configuration parameters from a GPIB driver file on your disk and displays them for your inspection You can alter any of the parameters to suit your special requirements Once you have finished modifying the configurable parameters these changes can be saved into the GPIB driver file on disk when you exit the ibconf program The simplest way to use ibconf is to change to the directory that contains the installed GPIB distribution files and enter the following command ibconf Upper and Lower Levels of ib
46. ibconfig Board Configuration Parameter Options Continued Options Options Constants Values Legal Values IbeWriteAdjust 0 0014 0 byte swapping 1 Swap pairs of bytes during write Default zero IbcSendLLO 0x0017 zero Do not send LLO when putting a device online ibfind or ibdev non zero Send LLO when putting a device online ibfind or ibdev Default zero IbcPPollTime 0 0019 0 Use the standard duration 2 us when conducting a parallel poll 1 to 17 Use a variable length duration when conducting a parallel poll The duration represented by 1 to 17 corresponds to the ibtmo values Default zero IbcEndBitIsNormal 0x001A zero Do not set the END bit of ibsta when an EOS match occurs during a read operation non zero Set the END bit of ibsta when an EOS match occurs during a read operation Default non zero continues National Instruments Corp 5 31 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBCONFIG 3 continued IBCONFIG 3 Table 5 4 ibconfig Board Configuration Parameter Options Continued Options Options Constants Values Legal Values IbcSignalNumber 0x001C The UNIX signal number that the driver sends to the user process when the condition designated in ibsgnl OCcurs Default 2 IbcHSCableLength 0 001 0 High speed handshaking is disabled 1 to 15 The number of meters of GPIB cable
47. identify the last byte of a data string ibeot is used primarily to send variable length data The sending of END with the EOS character is determined by the ibeos function and is not affected by the ibeot function The assignment made by this function remains in effect until ibeot is called again the ibonl or ibfind function is called or the system is restarted When ibeot is called and an error does not occur iberr is returned with a one if automatic END message was previously enabled or with a zero if it was previously disabled Device IBEOT Function If ud specifies a device the END termination message method that is selected is used on all device I O write operations to that device Board IBEOT Function If ud specifies an interface board the END termination message method that is selected is used on all board I O write operations regardless of what device is written to Refer also to JBEOS NI 488 2M Reference Manual 5 42 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBEOT continued IBEOT Device Function Example Send the END message with the last byte of all subsequent writes to the device plotter plotter ibfind dev5 ibeot plotter 1 ibwrt plotter wrt cnt Board Function Examples 1 Stop sending END with the last byte ibeot brd0 0 2 Sendthe END message with the last byte of all write operations ibeot brd0 1 ibwrt brdO wrt
48. in your system The NI 488 2M software uses this information to select the appropriate timing in the high speed handshaking mode Default 15 NI 488 2M Reference Manual 5 32 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBCONFIG 3 continued IBCONFIG 3 Table 5 5 lists the options you can use with ibconfig when ud isa device descriptor or a device index The following is an alphabetical list of the option constants included in Table 5 5 Constants Values Constants Values IbcEndBitIsNormal 0x001A IbcREADDR 0x0006 IbcEOSchar 0x000F bcReadAdjust 0x0013 IbcEOScmp 0x000E IbcSAD 0x0002 IbcEOSrd 0x000C bcSPollTime 0x0018 IbcEOSwrt 0x000D IbcTMO 0x0003 IbcEOT 0x0004 IbcWriteAdjust 0x0014 bcPAD 0x0001 IbcUnAddr 0x001B Table 5 5 ibconfig Device Configuration Parameter Options Options Options Constants Values Legal Values 0 0001 Changes the primary address of the device Identical to ibpad Default determined by ibconf IbcSAD 0 0002 Changes the secondary address of the device Identical to ibsad Default determined by ibconf IbcTMO 0x0003 Changes the device I O timeout limit Identical to ibtmo Default determined by ibconf IbcEOT 0x0004 Changes the data termination method for writes Identical to ibeot Default determined by ibconf continues National Instruments Corp 5 33 NI 488 2M Reference Manual NI 4
49. is not CIC If it is not Active Controller the GPIB board takes control and asserts ATN prior to sending the command bytes The GPIB board remains Active Controller afterward NI 488 2M Reference Manual 5 24 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBCMD 3 continued IBCMD 3 In the examples that follow GPIB commands and addresses are coded as printable ASCII characters If values correspond to printable ASCII characters it is simplest to use the ASCII characters to specify the values Refer to Appendix A for the ASCII characters corresponding to a numeric value Board Function Examples 1 Unaddress all Listeners UNL or ASCII and address a Talker at hex 46 ASCII F and a Listener at hex 31 ASCII 1 ibcmd F1 3 UNL TAD LAD 2 Same as Example 1 except the Listener has a secondary address of hex 6E ASCII n ibemd brd0 F1n 4 UNL TAD LAD SAD 3 Clear all GPIB devices with the Device Clear DCL or hex 14 command brd0 14 1 ee DCL xf 4 Clear two devices with listen addresses of hex 21 ASCII and hex 28 ASCII left parenthesis with the Selected Device Clear SDC or hex 04 command ibemd brd0 x04 4 UNL LAD LAD SDC 5 Trigger any devices previously addressed to listen with the Group Execute Trigger GET or hex 08 command ibcmd brd0 x08 1 GET 6 Serial poll
50. lets you input both NI 488 functions and NI 488 2 routines from the keyboard You can easily control instruments and receive status and error information without writing an application program ibic is described with step by step instructions in Chapter 6 ibic General Programming Information The following facilities or operations are common to all programming options and languages e Status Word ibsta e Error Codes iberr e Count Variables ibcnt e Read and Write Termination You should understand these topics thoroughly to take full advantage of the NI 488 2M driver s capabilities The next several paragraphs explain the status word ibsta the error variable iberr and the count variable These variables are updated after each function to reflect the status of the device or board just accessed Status Word ibsta All functions return a status word containing information about the state of the GPIB and the GPIB interface board You can test for the conditions reported in the status word to make decisions about continued processing The status word is returned in the variable ibsta In addition calls can be made as functions as opposed to subroutines and the status word is returned as the integer value of the function NI 488 2M Reference Manual 3 6 National Instruments Corp Chapter 3 Understanding the NI 488 2M Software The status word contains 16 bits of which 14 are meaningful A bit valu
51. limit is too short use ibtmo to change it printf Waiting for RQS n printf nn if ibwait dvm TIMO RQS amp ERR TIMO gpiberr ibwait Error exit 1 Because neither a timeout nor an error occurred ibwait must have returned on RQS Next serial poll the device if ibrsp amp spr amp ERR gpiberr ibrsp Error exit 1 Now test the status byte If spr is 0x50 the Fluke 45 has valid data to send otherwise it has a fault condition to report if spr 0x50 dvmerr Fluke 45 Error spr exit 1 If the data is valid read the measurement if ibrd dvm rd 10L amp ERR gpiberr ibrd Error exit 1 rd ibcnt 0 printf Reading s n rd Call the ibonl function to disable device DVM ibonl 0 National Instruments Corp 5 93 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 void gpiberr char msg This routine would notify you that an ib call failed xf printf Ss n msg printf ibsta amp H x lt ibsta if ibsta amp ERR printf ERR if ibsta amp TIMO printf TIMO if ibsta amp END printf END if ibsta amp SROI printf SRQI if ibsta amp ROS printf RQS if ibsta amp CMPL printf eA if ibsta amp LOK printf y if ibsta amp REM printf E if ibsta amp CIC printf CIC
52. measurement reading The GET message is represented by the hex value 8 GPIBO ibcmd 08 0138 cmpl cic atn tacs count 1 Wait for the DVM to set SRQ or for a timeout if the current timeout limit is too short use ibtmo to change it GPIBO ibwait TIMO SROI 1138 srqi cmpl cic atn tacs Set up the device for a serial poll The question mark character represents the Unlisten UNL command The space character represents the controller s listen address The hex value 18 represents the Serial Poll Enable function while A represents the talk address of the device GPIBO x18A 1174 srqi cmpl rem cic atn lacs count 4 NI 488 2M Reference Manual 6 24 National Instruments Corp Chapter 6 ibic Read the status byte The status byte returned may vary depending on the device used GPIBO ibrd 1 0164 cmpl rem cic lacs count 1 50 P Complete the serial poll by sending the Serial Poll Disable SPD message The hex value 19 represents the serial poll disable function GPIBO ibcmd 19 0174 cmpl rem cic atn lacs count 1 Because the DVM and the NI 488 are still addressed to talk and to listen the measurement can be read GPIBO ibrd 20 2164 end cmpl rem cic lacs OD 4E 44 43 56 2D 30 NDCV 0O 30 30 2E 30 30 34 37 45 00 0047E 2B 30 OD OA O0 Exit ibic GPIBO q National Instruments Corp 6 25 NI 488 2M Reference Manual Appendix
53. of ibconf Default Configurations The NI 488 2M driver has factory default configurations For example the default device names of the 16 GPIB devices are dev1 through dev16 You may want to change the names to more descriptive ones such as meter for a digital multimeter Note You can only connect 14 devices to each GPIB card in your system You may use ibconf to look at the current default settings in the driver file If you do not make changes to the NI 488 2M driver using ibconf the default configurations of the software remain in effect National Instruments Corp 2 7 NI 488 2M Reference Manual Installation and Configuration of NI 488 2M Software Chapter 2 Default Values The following are the default values of the driver e There are 16 devices with symbolic names dev1 through dev16 e There are two access boards with symbolic names gpib0 and gpibl The access board names cannot be changed e The GPIB addresses of the 16 devices are the same as the device number For example dev1 is at address 1 These devices assigned to gpib0 as their access board e GPIB interface board is System Controller of its independent bus and has a GPIB address of 0 The END message is sent with the last byte of each data message to a device No End Of String EOS character is recognized e The time limit on I O and wait function calls is set for approximately 10 s e Each GPIB interface board has its own defa
54. request Any device can drive the SRQ line to asynchronously request service from the Controller with the SRQ line EOI end or identify The EOI line has two purposes The Talker uses the EOI line to mark the end of a message string The Controller uses the EOI line to tell devices to identify their response in a parallel poll NI 488 2M Reference Manual D 4 National Instruments Corp Appendix Operation of the GPIB Physical and Electrical Characteristics Devices are usually connected with a cable assembly consisting of a shielded 24 conductor cable with both a plug and receptacle connector at each end This design allows devices to be linked in either a linear or a star configuration or a combination of the two See Figures D 1 D 2 and D 3 The standard connector is the Amphenol or Cinch Series 57 Microribbon or Amp Champ type An adapter cable using a non standard cable and or connector is used for special interconnection applications The GPIB uses negative logic with standard TTL logic level When DAV is true for example it is a TTL low level lt 0 8V and when DAV is false it is a TTL high level 2 2 0V National Instruments Corp D 5 NI 488 2M Reference Manual Operation of the GPIB Appendix D DIO1 DIOS DIO2 DIO6 DIO3 DIO7 DIO4 DIO8 EOI REN DAV GND twisted with DAV NRFD GND twisted with NRFD NDAC 8 GND with NDAG IFC GND twisted with IFC SRQ GND twisted with SRQ ATN GND t
55. run ibic summarizes the NI 488 2 and NI 488 ibic functions and summarizes the auxiliary functions that ibic supports Appendix A Multiline Interface Messages is a listing of Multiline Interface Messages Appendix B Common Errors and Their Solutions singles out the most common errors users have encountered and some possible solutions Appendix C Redirection to the GPIB explains how to redirect data to a GPIB printer plotter or other device Appendix D Operation of the GPIB describes the operation of the GPIB About This Manual e Appendix E Customer Communication contains forms for you to complete to facilitate communication with National Instruments concerning our products e Glossary contains an alphabetical list of terms used in this manual and a description of each e Index contains an alphabetical list of key terms and topics used in this manual including the pages where each one can be found Conventions Used in This Manual The following conventions are used to distinguish elements of text throughout this manual italic monospace bold monospace italic monospace lt gt lt gt Italic text denotes emphasis a cross reference or an introduction to a key concept Text in this font denotes text or characters that are to be literally input from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk dri
56. the device name is unknown Enable disable DMA Change disable EOS mode write Enable disable END message Open device and return unit descriptor continued 5 5 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Call Syntax ibgts ibist iblines ibln ibloc ibonl ibpad ibpct ibppc ibrd ibrdf ibrpp ibrsc ibrsp ibrsv ibsad ibsic ibsre ibtmo ibtrg ibwait ibwrt Table 5 1 C NI 488 Functions Continued Go from Active Controller to Standby Set clear ind status bit for Parallel Polls Get status of GPIB lines Check for presence of device on bus ud v ud v board lines pad sad listen ud ud v ud v ud ud v ud rd ent ud fl1name ud amp ppr ud v ud amp Spr ud v ud v ud ud v ud v ud ud mask ud wrt cnt ibwrtf ud flname NI 488 2M Reference Manual Go to Local Chapter 5 Place device or board online offline Change Primary Address Pass Control Parallel Poll Configure Read data to string Read data to file Conduct a Parallel Poll Request release System Control Return serial poll byte Request service set change serial poll Change disable Secondary Address 5 6 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions Writing an NI 488 Program The following paragraphs demonstrate how to use the NI 488 functions An e
57. until it receives its listen address The ESAC error occurs if the GPIB board is not System Controller When ibsre is called and an error does not occur the previous REN state is stored in iberr Refer also to JBRSC Board Function Examples 1 Place the device at listen address hex 23 ASCII in remote mode ibsre brd0 1 ibcmd brd0 1 2 To exclude the ability of the device to return to local mode send the Local Lockout LLO or hex 11 command or include it in the command string at 120 in Example 1 ibcmd brd0 x11 1 ibcmd brd0 4Nx11 2 3 Return all devices to local mode ibsre brd0 0 NI 488 2M Reference Manual 5 78 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBTMO 3 IBTMO 3 Purpose Change or disable time limit Syntax int ibtmo intud int v ud specifies a device or an interface board v specifies the time limit as follows Table 5 9 Timeout Code Values National Instruments Corp 5 79 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBTMO 3 continued IBTMO 3 Note If is zero no limit is in effect ibtmo is needed only to alter the value from its configuration setting The assignment made by this function remains in effect until ibtmo is called again ibonl or ibfind function is called or the system is restarted The ibtmo function changes the
58. v is a number between hex 60 and hex 7E that number becomes the secondary GPIB address device or interface board If v is hex 7F or zero secondary addressing is disabled ibsad is needed only to alter the secondary address value from its configuration setting The assignment made by this function remains in effect until ibsad is called again the ibonl or ibfind function is called or the system is restarted When ibsad is called and an error does not occur the previous secondary address is stored in iberr Device IBSAD Function If ud specifies a device the function enables or disables extended GPIB addressing for the device When secondary addressing is enabled the specified secondary GPIB address of that device is sent automatically in subsequent device I O functions Board IBSAD Function If ud specifies an interface board the ibsad function enables or disables extended GPIB addressing and when enabled assigns the secondary address of the GPIB board Refer also to BPAD and IBONL Device Function Example 1 Change the secondary GPIB address of plotter from its current value to hex 6A ibsad dvm 0x6A National Instruments Corp 5 73 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBSAD 3 continued IBSAD 3 2 Disable secondary addressing for the device dvm ibsad dvm 0 0 or Ox7F can be used Board Function Examples 1 Change the secondary GPIB addr
59. which opened device or board to access SET changes the prompt to the new symbolic name SET is also used to switch between NI 488 mode and NI 488 2 mode Following is an example of how to use the SET command devi set plotter id 32006 plotter This example assumes that ibconf was used to give a device the name plotter The following example summarizes the use of ibfind and SET ina typical program NI 488 2M Reference Manual 6 6 National Instruments Corp Chapter 6 ibic ibfind devl id 32006 dev1 ibfind plotter plotter ibwrt F3T7GO 0100 cmp1 count 6 Plotter set devl devi ibwrt X7Y39G0 0100 cmp1 count 7 dev1 ibic Functions and Syntax ibic displays the following information about each function call immediately after that call e ibrd data messages are displayed on the screen in hex and ASCII formats e global variables ibsta ibcnt and iberr are displayed on the screen ibic and programming languages of Chapter 5 NI 4858M Software Characteristics and Functions differ in the syntax of the function call The main differences are that ibwrt and ibcmd messages are entered as strings from the keyboard The syntax for ibic is shown in Tables 6 1 and 6 2 The unit descriptor ud is not explicitly a part of ibic function syntax Before using any device or board first call ibfind to open that unit and to pass the unit descriptor to ibic The screen prompt ide
60. 2 for more information about these other factors The default value is 500 ns NI 488 2M Reference Manual 2 12 National Instruments Corp Chapter 2 Installation and Configuration of NI 488 2M Software UNIX Signal Board Characteristic Only This field selects the UNIX signal that would be sent as a result of the ibsgnl function call The default value for this characteristic is 2 DMA Mode Board Characteristic Only Data transfers can be performed either by DMA or by programmed I O PIO To disable DMA and force all read and write operations to be performed using PIO set this option to no The default option for this characteristic is yes Exiting ibconf After you have made all your changes you can exit ibconf by pressing Control O The program first displays the prompt Save changes before exiting Typing a y response causes the changes to be written to the file on disk and the message to be displayed Configuration saved To activate reboot unix Typing an n response causes the message Handler file unchanged to be displayed Using Your NI 488 2M Software The NI 488 2M software consists of a high speed driver and several utilities to help in developing and debugging an application program The NI 488 2M driver can be accessed in the following two ways directly with the NI 488 functions or with the NI 488 2 routines National Instruments Corp 2 13 NI 488 2M Reference Manual Installation and Configurat
61. 3 WaitSRQ 3 16 4 5 4 7 4 36 6 12 write call 3 13 write data 5 6 write operations 2 11 2 12 2 13 3 10 3 13 National Instruments Corp Index 17 NI 488 2M Reference Manual
62. 3 16 B 6 to B 7 event signal 3 18 examining board or device characteristics 2 5 to 2 7 extended addressing 2 9 F file operations 3 15 FindLstn 3 16 4 6 4 13 FindRQS 3 16 4 6 4 14 function calls 3 14 functions 2 14 3 2 to 3 11 See also NI 488 M functions 6 12 6 12 NI 488 2M Reference Manual Index 4 National Instruments Corp Index G go to local 3 9 GPIB 1 1 bus timing 2 12 cable 2 12 connector D 6 interface functions 4 7 lines 5 6 D 3 to D 4 data D 3 handshake D 3 interface management D 4 operation D 1 to D 9 signals D 3 to D 4 SRQ line 3 8 group execute trigger 3 10 H driver 2 1 2 13 4 1 5 2 driver functions 3 18 handshake lines D 3 help in ibic 6 17 high speed timing 2 5 I 3 14 to 3 15 address 3 15 calls 5 5 low level 4 2 to 4 3 multiple device 4 2 4 3 operations 3 8 3 9 3 15 SendList 6 3 simple device 4 2 4 3 termination 2 11 timeout 4 5 ibask 5 5 5 11 to 5 20 ibbna 5 5 5 21 6 10 ibcac 3 13 5 5 5 22 6 10 National Instruments Corp Index 5 NI 488 2M Reference Manual Index ibelr 5 5 5 23 6 10 2 9 3 3 3 13 3 14 5 5 5 24 to 5 25 6 10 ibcnt 3 6 3 12 3 15 3 17 6 1 6 9 ibconf 3 4 3 12 3 13 3 14 3 16 4 5 access board names 2 8 default configurations 2 7 default values of the driver 2 8 device names 2 8 exiting 2 13 lower level device board characteristics 2 5 addressing 2 6 2
63. 3 7 3 9 3 11 3 19 remote enable 3 9 5 2 remote enable line 5 6 remote GPIB programming of devices 4 5 remote program mode 5 2 remote state 3 7 3 9 3 19 remote with lockout 4 7 REN D 4 See remote enable renaming a device 2 4 request service 5 6 ResetSys 4 6 4 23 6 12 RFD 2 12 routines 2 14 3 1 to 3 2 3 4 to 3 6 See NI 488 2 routines routines ibic See ibic routines RQS 3 7 3 8 to 3 9 3 16 5 3 5 4 NI 488 2M Reference Manual Index 14 National Instruments Corp Index S SCPI 3 1 secondary address 2 9 5 6 selected device clear 3 10 self tests 4 7 Send 4 6 4 24 6 12 send commands 5 5 SendCmds 3 14 4 6 4 25 6 12 SendDataBytes 3 14 4 6 4 26 6 12 SendIFC 3 9 3 13 3 14 4 7 4 27 6 12 SendList 4 7 4 28 6 3 6 12 SendLLO 4 7 4 29 6 12 SendSetup 3 14 4 7 4 30 6 12 serial poll set change 5 6 serial poll byte 5 6 serial polling 3 3 3 9 3 16 See also automatic serial polling serial polls 4 5 timeout 4 5 service request See SRQ service requests 3 8 4 6 4 7 See also SRQ SetRWLS 4 7 4 31 6 12 shadow handshake 3 8 3 10 3 14 signal assignment D 6 signal interrupt 3 18 5 4 signal masks 3 19 CIC 3 19 DCAS 3 19 DTAS 3 19 LACS 3 19 LOK 3 19 REM 3 19 SRQI 3 19 TACS 3 19 simple device control 4 2 4 3 I O 4 2 4 3 single board configuration device functions 5 2 software configuration See also ibconf software
64. 3 8 3 10 3 13 3 14 5 6 5 46 6 10 ibic 2 14 3 6 6 1 to 6 25 auxiliary functions supported 6 16 to 6 19 board functions sample programs 6 23 to 6 25 byte count 6 16 device functions sample programs 6 22 to 6 23 EOS adding 6 8 error 6 15 execute indirect file 6 19 exiting 6 8 6 20 functions 6 9 to 6 11 ibbna 6 10 ibcac 6 10 ibclr 6 10 ibemd 6 10 ibent 6 9 ibdev 6 5 to 6 7 6 10 ibdma 6 10 ibeos 6 10 National Instruments Corp Index 7 488 2 Reference Manual Index ibeot 6 10 ibfind 6 4 6 10 ibgts 6 10 ibist 6 10 iblines 6 10 ibln 6 10 ibloc 6 10 ibonl 6 10 ibpad 6 10 ibpct 6 11 ibppc 6 11 ibrd 6 7 6 9 6 11 ibrdf 6 11 ibrpp 6 11 ibrsc 6 11 ibrsp 6 11 ibrsv 6 11 ibsad 6 11 ibsic 6 11 ibsre 6 11 ibtmo 6 11 ibtrg 6 11 ibwrt 6 7 6 11 ibwrtf 6 7 help 6 4 6 17 iberr 6 9 ibsta 6 9 instrument control 3 6 print 6 20 Receive 6 3 repeat function 6 19 repeat previous function 6 17 to 6 18 routines 6 11 to 6 14 AllSpoll 6 11 DevClear 6 11 DevClearList 6 11 EnableLocal 6 11 EnableRemote 6 11 FindLstn 6 12 FindRQS 6 12 PassControl 6 12 PPoll 6 12 PPollConfig 6 12 NI 488 2M Reference Manual Index 6 National Instruments Corp Index PPollUnconfig 6 12 RcvRespMsg 6 12 ReadStatusByte 6 12 Receive 6 12 ReceiveSetup 6 12 ResetSys 6 12 sample programs 6 20 to 6 22 Send 6 15 SendCmds 6 12 SendDataBytes 6 12 SendIFC
65. 488M Software Characteristics and Functions IBPPC 3 continued IBPPC 3 Board IBPPC Function If ud specifies an interface board the board responds to a parallel poll by setting its Local Poll Enable LPE message to v Refer also to BCMD and IBIS Device Function Example 1 Configure dvm to respond with data line DIOS true ist 0 0x64 2 Configure dvm to respond with data line DIO1 true 1541 0x68 3 Cancel parallel poll configuration of ibppc dvm 0x70 Board Function Examples Configure board to respond with data line DIOS true ist 0 ibppc brd0 0x64 National Instruments Corp 5 61 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBRD 3 IBRD 3 Purpose Read data from a device to a string Syntax int ibrd int ud char rd unsigned long cnt ud specifies a board or a device rd is the storage buffer for data ibrd terminates when one of the following events occurs allocated buffer becomes full e Anerror is detected e time limit is exceeded e An END message is detected e An EOS character is detected if this option is enabled Transfer count may be less than expected if any of these terminating events except for the first event occurs When ibrd completes ibsta holds the latest device status ibcnt is the number of bytes read and if the ERR bitin i
66. 5 6 5 73 to 5 74 ibsgnl 5 75 to 5 76 ibsic 5 6 5 77 ibsre 5 6 5 78 ibwait 5 3 5 4 5 6 5 83 to 5 85 ibwrt 5 5 5 6 5 86 to 5 87 ibwrtf 5 6 5 88 to 5 89 NI 488 programming See programming with NI 488 NLend 3 17 NRFD D 3 NULLend 3 17 offline 5 6 online 5 6 open device 5 5 opening boards and devices 3 4 operations from front of device 4 5 P parallel poll 4 6 5 6 configuring 5 6 PassControl 4 6 4 15 6 12 physical characteristics D 5 to D 8 PIO See programmed I O PPoll 4 6 4 16 6 12 PPollConfig 4 6 4 17 6 12 PPollUnconfig 4 6 4 18 6 12 primary address 2 9 5 6 programmed I O 2 13 programming interactively 2 14 programming with NI 488 5 7 to 5 9 analyzing and presenting data 5 9 clearing the device 5 7 National Instruments Corp Index 13 488 2 Reference Manual Index configuring the device 5 8 initializing the system 5 7 taking measurements 5 8 triggering the device 5 8 programming with NI 488 functions example programs 5 90 to 5 99 board functions 5 96 to 5 99 device functions 5 92 to 5 95 R RcvRespMsg 3 14 4 6 4 19 6 12 read and write functions 3 14 read and write operations 2 13 read and write termination 3 6 3 17 read data 5 6 read functions 3 8 read operations 2 10 2 13 3 11 4 6 ReadStatusByte 4 6 4 20 6 12 Receive 4 6 4 21 6 3 6 12 ReceiveSetup 3 14 4 6 4 22 6 12 redirection to the GPIB C 1 REM
67. 5 85 U MTA21 75 165 117 u MSA21 PPD 56 126 86 V MTA22 76 166 118 v MSA22 PPD 57 127 87 W MTA23 77 167 119 w MSA23 PPD 58 130 88 X 24 78 170 120 x MSA24 PPD 59 131 89 Y MTA25 79 171 121 MSA25 PPD 5A 132 90 7 26 7 172 122 2 MSA26 PPD 5B 133 91 MTA27 7B 173 123 MSA27 PPD 5C 134 92 MTA28 7C 174 124 MSA28 PPD 5D 135 93 MTA29 7D 175 125 MSA29 PPD 5 136 94 MTA30 7E 176 126 MSA30 PPD 5F 137 95 _ UNT TF 177 127 DEL PPE Parallel Poll Enable SPE Serial Poll Enable PPU Parallel Poll Unconfigure TCT Take Control SDC Selected Device Clear UNL Unlisten SPD Serial Poll Disable UNT Untalk National Instruments Corp A 3 NI 488 2M Reference Manual Appendix Common Errors and Their Solutions Some errors occur more frequently than others These common errors and their solutions are listed in this appendix according to the error code that is returned from the function as indicated by iberr A full explanation of all possible errors can be found in the Error Variable iberr discussion in Chapter 3 Understanding the NI 488 2M Software Also in this appendix are descriptions of error situations that do not return an error code ECIC 1 Error Condition Function requires GPIB board to be Controller In Charge Solutions e Run ibconf and make sure the board being used gpibO0 or gpibl is configured to be the System Controller e fexecuting board functions call ibsic to become Controller In Charge before
68. 6 5 3 5 4 5 6 5 83 to 5 85 ibwrt 2 9 2 13 3 13 5 5 5 6 5 86 to 5 87 6 9 6 11 ibwrtf 3 15 5 6 5 88 to 5 89 6 11 IEEE 488 specification 3 17 TEEE 488 2 3 1 1992 specification 4 1 IFC D 4 See interface clear initializing GPIB system 4 6 installation of software 2 1 interactive control program 2 14 interface bus interactive control See ibic interface clear 3 9 3 13 5 2 5 6 interface management lines D 4 interface messages A 1 to A 3 D 1 interrupt setting 2 8 L LACS 3 7 3 10 3 11 3 19 language interface 2 14 linear configuration D 7 listen address 2 9 3 9 3 10 3 13 listener 3 19 D 1 to D 2 NI 488 2M Reference Manual Index 10 National Instruments Corp Index listeners find all 4 6 LLO See local lockout local 5 6 lockout 3 9 3 19 5 2 local 3 9 5 2 message 4 7 LOK 3 7 3 9 3 11 3 19 lower level device board characteristics 2 5 to 2 6 See also ibconf M message exchange initialization 4 23 messages device dependent D 1 interface D 1 multiboard configuration 5 2 multiboard GPIB system 3 5 multiboard driver 3 5 multiline interface messages A 1 to A 3 multiple device control 4 2 4 3 multiple device I O 4 2 4 3 N NDAC D 3 NI 488 2 routines 3 1 to 3 2 3 4 to 3 6 4 1 to 4 43 AllSpoll 4 5 4 8 compatibility with NI 488 board functions 4 4 DevClear 4 5 4 8 DevClearList 4 5 4 10 EnableLocal 4 5 4 11 EnableRemote 4 5 4 12 FindLst
69. 88M Software Characteristics and Functions Chapter 5 IBCONFIG 3 continued IBCONFIG 3 Table 5 5 ibconfig Device Configuration Parameter Options Continued Options Options Constants Values Legal Values IbcREADDR 0x0006 zero No unnecessary readdressing is performed between device level reads and writes non zero Addressing is always performed before a device level read or write Default determined by ibconf IbcEOSrd Ox000C non zero Terminate reads when the EOS character is read Default determined by ibconf IbcEOSwrt 0x000D zero Do not send EOI with the EOS character during write operations non zero Send EOI with the EOS character during writes Default determined by ibconf IbcEOScmp 0x000E zero Use 7 bits for the EOS character comparison non zero Use 8 bits for the EOS character comparison Default determined by ibconf IbcEOSchar OxO00F Any 8 bit value This byte becomes the new EOS character Default determined by ibconf IbcReadAdjust 0x0013 0 No byte swapping 1 Swap pairs of bytes during a read Default zero continues NI 488 2M Reference Manual 5 34 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBCONFIG 3 continued IBCONFIG 3 Table 5 5 ibconfig Device Configuration Parameter Options Continued Options Options Constants Values Legal Values IbeWriteAdjust 0 0014 0 byte swapping
70. DR 3 EADR occurs when the GPIB board is CIC and is not addressing itself before read and write functions This error is extremely unlikely to occur on a device function For a board function the remedy is to be sure to send the appropriate Talk or Listen address using SendCmds SendSetup or ReceiveSetup before attempting SendDataBytes or RcvRespMsg or ibcmd before attempting ibwrt or ibrd EADR is also returned by the function ibgts when the shadow handshake feature is requested and the GPIB ATN line is already unasserted In this case the shadow handshake is not possible and the error is returned to notify you of that fact ibgts should almost never be called except immediately after call 3bcmd causes ATN to be asserted EARG 4 EARG results when an invalid argument is passed to a function call The following are some examples ibtmo called with a value not in the range 0 through 17 ibeos called with meaningless bits set in the high byte of the second parameter ibpad or ibsad called with invalid addresses ibppc called with invalid parallel poll configurations A board function made with a valid device descriptor or a device function made with a valid board descriptor Note EDVR is returned if the descriptor is invalid 5 ESAC results when SendIFC ibsic EnableRemote or ibsre is called when the GPIB board does not have System Controller capability The remedy is to give the GPIB bo
71. END or end message National Instruments Corp Glossary An NI 488M file that contains code that must be placed at the beginning of an application program to allow it to properly access the driver ugpib h is the declaration file for programs written in C See language interface An instrument peripheral computer or other electronics equipment that can be programmed over the GPIB See board See DCL A message sent from one device to another device such as programming instructions data or device status See command or interface message A function that operates on or otherwise pertains to a GPIB device rather than to the GPIB interface board in the computer See board function The GPIB lines that are used to transmit command or data bytes from one device to another High speed data transfer between the GPIB and memory that is not handled directly by the CPU Not available on some systems See programmed I O Common term for software used to manipulate a device or interface board digital voltmeter A message that signals the end of a data string END is sent by asserting the GPIB End Or Identify EOD line with the last data byte G 3 NI 488 2M Reference Manual Glossary EOI EOS or EOS byte FIFO G General Purpose Interface Bus GET or group execute trigger go to local GPIB GPIB address GPIB board group execute trigger GTL or go to local NI 488 2M Reference Manual
72. Example Place the devices at GPIB addresses 8 and 9 in remote mode Addr4882_2 addresslist 3 8 9 NOADDR EnableRemote 0 addresslist NI 488 2M Reference Manual 4 12 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines FindLstn 3 FindLstn 3 Purpose Find all Listeners Syntax void FindLstn int board Addr4882 t addresslist Addr4882_t resultlist int limit board specifies a board number addresslist contains a list of primary GPIB addresses terminated by the value NOADDR These addresses are tested in turn for the presence of a listening device If found the addresses are entered into the resultlist Ifno listening device is detected at a particular primary address all the secondary addresses associated with that primary address are tested and detected Listeners are entered into resultlist The limit argument specifies how many entries should be placed into the resultlist array If more Listeners are present on the bus the list is truncated after 1imit entries have been detected and the error ETAB will be reported in iberr The variable ibcnt will contain the number of addresses placed into resultlist Because for any given primary address there may be multiple secondary addresses that respond as Listeners the result list array should in general be larger than the addresslist array In any event the resultlist with limit being the maximum possible results array
73. Function Example Obtain the serial poll response spr byte from the device tape ibrsp tape amp 5 National Instruments Corp 5 71 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBRSV 3 IBRSV 3 Purpose Request service and or set or change the serial poll status byte Syntax intibrsv intud int v ud specifies an interface board v is the status byte that the GPIB board provides when serial polled by another device that is the GPIB CIC If bit 6 the hex 40 bit is set the GPIB board additionally requests service from the Controller by asserting the GPIB SRQ line The ibrsv function is used to request service from the Controller using the Service Request SRQ signal and to provide a system dependent status byte when the Controller serial polls the GPIB board When ibrsv is called and an error does not occur the previous value of v is stored in iberr Board Function Examples 1 Set the serial poll status byte to hex 41 which simultaneously requests service from an external CIC stb 1 ibrsv brd0 stb 0x41 2 Change the status byte without requesting service ibrsv brd0 0x23 NI 488 2M Reference Manual 5 72 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBSAD 3 IBSAD 3 Purpose Change or disable Secondary Address Syntax int ibsad intud int v ud specifies a device or an interface board If
74. I O completed Controller In Charge a Remote State 1m Attention is asserted brd DTAS Enpe Device Trigger State DCAS o 1 bd __ Device Clear State Error Code If an NI 488 function or NI 488 2 routine completes with an error ibic also displays the error mnemonic The following example illustrates the result if an error condition occurs in the data transfer dev1 ibwrt f2t3x 8100 err cmpl ERROR ENOL COUNT 1 dev1 In this example there are no Listeners perhaps dev1 is powered off National Instruments Corp 6 15 NI 488 2M Reference Manual ibic Chapter 6 Byte Count When an I O function completes ibic displays the actual number of bytes sent or received regardless of the existence of an error condition Auxiliary Functions Table 6 4 summarizes the auxiliary functions that ibic supports Table 6 4 Auxiliary Functions That ibic Supports Select active device or board set udname or set 488 2 n mamona Execute previous n3 Display ing onsereen erit string 6 meum mea a Notes for Table 6 4 l udname is the symbolic name of the new device or board for example ibfind 1 or set gpib0 2 Call ibfind initially to open each device or board 3 Ifoption is omitted a menu of options appears NI 488 2M Reference Manual 6 16 National Instruments Corp Chapter 6 ibic Replace functi
75. IB and placed into the pre allocated string data The count argument is of type long however integer values and variables may also be passed termination is a flag used to describe the method of signaling the end of the data If it is a value between 0 and hex OOFF the ASCII character with the corresponding hex value is considered the termination character and the read is stopped when the character is detected If termination is the constant STOPend defined in the header file ugpib h then the read is stopped when EOI is detected RcvRespMsg assumes that the GPIB Talker and Listeners have already been addressed by a prior call to routines such as ReceiveSetup Receive or SendCmds Thus it is used specifically to skip the addressing step of GPIB management The Receive routine is normally used to accomplish the entire sequence of addressing followed by the reception of data bytes Example Receive 100 bytes from an already addressed Talker The transmission should be terminated when a linefeed character is detected char data 100 RcvRespMsg 0 data 100 n National Instruments Corp 4 19 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 ReadStatusByte 3 ReadStatusByte 3 Purpose Serial poll a single device to get its status byte Syntax void ReadStatusByte intboard Addr4882_t address short result board specifies a board number The indicated device is serial poll
76. IB device to receive data from another GPIB device The following example illustrates the use of the ibrd function dev1 ibrd 20 2100 end cmpl count 18 4E 44 43 56 28 30 30 30 NDCV 000 2E 30 30 34 37 45 2B 30 0047E 0 OD e This command acquires data from the device and displays it on the screen in hex format and in its ASCII equivalent along with information about the data transfer such as the Status Word and the Byte Count National Instruments Corp 6 7 NI 488 2M Reference Manual ibic Chapter 6 How to Exit ibic Typing e or q will return you to the operating system Adding Common EOS Characters Some GPIB instruments require special termination characters or End Of String EOS characters to indicate to the device the end of transmission If your device requires any EOS characters you must add these to the end of the data string sent out by the ibwrt statement The following example illustrates the addition of the two most commonly used EOS characters the carriage return and the linefeed dev1 ibwrt 5 1 0100 1 count 6 The r and n represent the carriage return and linefeed characters respectively See the Notes of Table 6 4 for a more detailed description on the representation of non printable characters Using SET If you are using NI 488 calls you use ibfind to open each device or board Once the device or board is opened use the auxiliary function SET to select
77. If a device times out while responding to its serial poll the error code EABO is returned in iberr and the index of the timed out device will appear in ibcnt Example Determine which one of the devices at addresses 8 9 and 10 are requesting service Addr4882 t addresslist 3 8 9 10 NOADDR short result FindROS 0 addresslist amp result NI 488 2M Reference Manual 4 14 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines PassControl 3 PassControl 3 Purpose control to another device with Controller capability Syntax void PassControl intboard Addr4882 t address board specifies a board number The GPIB Device Take Control message is sent to the device at the given address The parameter address contains in its low byte the primary GPIB address of the device to be passed control The high byte should be 0 if the device has no secondary address Otherwise it should contain the desired secondary address Example Pass control to a Controller connected to board 0 whose primary GPIB address is 9 PassControl 0 9 National Instruments Corp 4 15 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 PPoll 3 PPoll 3 Purpose Perform a parallel poll Syntax void PPoll int board short result board specifies a board number A parallel poll is conducted and the eight bit result is stored into result Only th
78. In the typical case of placing devices in Remote Mode With Lockout state the Set RWLS routine should be used Example Send the Local Lockout message to all devices connected to board 0 SendLLO 0 National Instruments Corp 4 29 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 SendSetup 3 SendSetup 3 Purpose Prepare particular devices to receive data bytes Syntax void SendSetup intboard Addr4882 t addresslist board specifies a board number The GPIB devices whose addresses are contained in the addresslist array are addressed as Listeners and the indicated board is addressed as a Talker Following this call it is common to call a routine such as SendDataBytes to actually transfer the data to the Listeners The parameter addresslist is an array for any size of address integers terminated by the value NOADDR This command would be useful to initially address devices in preparation for sending data followed by multiple calls of SendDataBytes to send multiple blocks of data thus eliminating the need to re address the devices between blocks Alternatively the Send routine could be used to send the first data block followed by SendDataBytes for all the subsequent blocks Example Prepare GPIB devices at addresses 8 and 9 to receive data bytes Then send both devices the five messages stored in a string array EOI is to be sent along with the last byte of the last message
79. Instruments Corp 6 21 NI 488 2M Reference Manual ibic Chapter 6 Return to the UNIX operating system 488 2 0 e Device Functions To communicate with a device first find the device name which was given to the device in the ibconf program ibfind dvm id 32005 DVM Clear the device You should check for ERR after each GPIB function call DVM ibclr 0100 cmp1 Write the function range and trigger source instructions to the DVM DVM ibwrt F3R7T3 0100 cmp1 count 6 Trigger the device DVM ibtrg 0100 cmp1 Wait for the DVM to request service or for a timeout if the current timeout limit is too short use ibtmo to change it DVM ibwait TIMO RQS 0800 ras Read the serial poll status byte This serial poll status byte will vary depending on the device used DVM ibrsp 0100 1 Poll 0x40 decimal 32 NI 488 2M Reference Manual 6 22 National Instruments Corp Chapter 6 ibic The read command displays the data on the screen both in hex values and their ASCII equivalents DVM ibrd 18 0100 cmp1 count 18 4E 44 43 56 20 30 30 30 NDCV 2E 30 30 34 37 45 28 30 00 4 OA OA 000 7E 0 Return to UNIX DVM Board Functions The following pages show how to execute board functions only not device functions For most applications board functions are not needed Begin by making the interface board the current board ibfind gpibO id 32006 G
80. LA or MTA address followed by an MSA address There are 31 of these secondary addresses for a total of 961 distinct listen or talk addresses for devices A GPIB command used to address a device to be a Talker There are 31 of these primary addresses One of the three GPIB handshake lines See handshake One of the three GPIB handshake lines See handshake A device or board that has been enabled or placed online by the ibfind function National Instruments Corp G 7 NI 488 2M Reference Manual Glossary parallel poll parallel poll configure parallel poll disable parallel poll enable parallel poll unconfigure PIO port address PPC or parallel poll configure PPD or parallel poll disable PPE or parallel poll enable PPU or parallel poll unconfigure programmed I O personal computer The process of polling all configured devices at once and reading a composite poll response See serial poll See PPC See PPD See PPE See PPU programmed I O See 7 0 address The GPIB command used to configure an addressed listener to participate in polls The GPIB command used to disable a configured device from participating in polls There are 16 PPD commands The GPIB command used to enable a configured device to participate in polls and to assign a DIO response line There are 16 PPE commands The GPIB command used to disable any device from participating in polls Low speed data tr
81. Manual 4 2 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines SendSetup RcvRespMsg ReceiveSetup The Simple Device I O routines can read and write to individual GPIB devices The Multiple Device I O routines can write the same message to multiple Listeners with a single message transmission The Simple Device Control routines direct various bus management instructions to individual devices The Multiple Device Control routines direct bus management instructions to multiple devices in the same message The Bus Management routines cause system wide functions to be performed or provide system wide status The Low Level I O routines are used to break down a higher level routine into more detailed instructions due to unusual situations routines take as their first parameter a board number selecting a GPIB interface board installed in the computer For the majority of cases there will be only one GPIB interface board installed and its board number will be 0 Therefore in the typical case a O is the first argument of all NI 488 2 routines Routines that operate on single devices have as their second parameter an integer that indicates the GPIB address of the device In the typical case of a device that uses only primary GPIB addressing this involves passing a simple integer in the range 0 to 30 corresponding to the primary GPIB address of the device In the more unusual case of
82. NI 488 2M Software Reference Manual February 1996 Edition Part Number 370963A 01 Copyright 1991 1996 National Instruments Corporation Rights Reserved National Instruments Corporate Headquarters 6504 Bridge Point Parkway Austin TX 78730 5039 512 794 0100 Technical support fax 512 794 5678 Branch Offices Australia 03 9 879 9422 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Canada Ontario 519 622 9310 Canada Qu bec 514 694 8521 Denmark 45 76 26 00 Finland 90 527 2321 France 1 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico 95 800 010 0793 Netherlands 0348 433466 Norway 32 84 84 00 Singapore 2265886 Spain 91 640 0085 Sweden 08 730 49 70 Switzerland 056 200 51 51 Taiwan 02 377 1200 U K 01635 523545 Limited Warranty The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a period of 90 days from date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace software media that do not execute programming instructions if National Instruments receives notice of such defects during the warranty period National Instruments does not warrant that the operation of the software shall be uninterrupted or error free A Return Material Authorization RMA n
83. O operation EBTO 9 Error Condition indicates that a hardware bus timeout occurred during an I O operation This is usually the result of an attempt by a DMA Controller to access non existent memory NI 488 2M Reference Manual B 4 National Instruments Corp Appendix Common Errors and Their Solutions ECAP 11 Error Condition ECAP results when a particular capability has been disabled in the driver and a call is made that attempts to make use of that capability Solution e Run ibconf and verify that the capability to do a particular call is enabled for example the interface board must be configured as System Controller to execute the ibsre function Check both device and board capabilities Restart after leaving ibconf if you made any changes EFSO 12 Error Condition File system error Solutions e Check the disk files to make sure names are properly specified and that the file exists f more room is needed on the disk delete some files e Rename any files which have the same name as a device named in ibconf or rename the device EBUS 14 Error Condition Command byte transfer error Solutions e Find out which device is abnormally slow to accept commands and fix the problem with the device e f more time is needed to send commands lengthen the time limit in ibconf or with ibtmo National Instruments Corp B 5 NI 488 2M Reference Manual Common Errors and Their Solutio
84. PIB address of the device sad legal values are hex 60 to or NO SAD or ALL SAD specifies the secondary GPIB address of the device The function ibln returns a non zero value in the variable listen ifa Listener is at the specified GPIB address Notice that the sad parameter can be a value in hex 60 to 7e or one of the constants NO SAD or ALL SAD You can test for a Listener using only GPIB primary addressing by making sad NO_SAD or you can test all secondary addresses associated with a single primary address a total of 31 device addresses when you set sad ALL SAD In this case ibln sends the primary address and all secondary addresses before waiting for NDAC to settle If the listen flag is true you must search only the 31 secondary addresses associated with a single primary address to locate the Listener The two special constants that can be used in place of a secondary address are as follows NO SAD 20 ALL SAD 1 If ud specifies a device ibln tests for a Listener on the board associated with the given device Refer also to JBDEV and IBFIND National Instruments Corp 5 51 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBLN 3 continued IBLN 3 Device Board Function Example Test for a GPIB Listener at pad 2 and sad 0x60 ibsta ibln ud 2 0x60 amp listen if listen No Listener found at this address NI 488 2M Reference Manual 5 52 Nat
85. PIBO Send the interface clear message IFC to all devices This clears the bus and asserts attention ATN on the bus The user should check for ERR after each GPIB function call to be safe GPIBO ibsic 0130 cmpl cic atn Turn on the remote enable signal REN GPIBO ibsre 1 0130 cmpl cic atn previous value 0 Set up the addressing for the device to listen and the computer to talk The question mark character represents the unlisten UNL command The character represents the talk address of the GPIB board which was calculated using the Multiline Interface Message chart in Appendix A National Instruments Corp 6 23 NI 488 2M Reference Manual ibic Chapter 6 The GPIB board is at GPIB primary address 0 Moving across to the Talk address column the appropriate ASCII character is an character Ina similar manner the character represents the listen address of the device which in this case is assumed to be at GPIB primary address 1 The Multiline Interface Message chart in Appendix A indicates that the listen address for a device at a primary address of 1 is an character GPIBO ibcmd Q0 0138 cmpl cic atn tacs count 3 Write the function range and trigger source instructions to the DVM Be sure an error has not occurred before proceeding with the sample program GPIBO ibwrt F3R7T3 0128 cmpl cic tacs count 6 Send the Group Execute Trigger message GET to trigger a
86. Return the device dvm to local state ibloc dvm Board Function Examples Return the interface board brdo to local state ibloc brd0 NI 488 2M Reference Manual 5 54 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBONL 3 IBONL 3 Purpose Place the device or interface board online or offline Syntax int ibonl intud int v ud specifies a device or an interface board If v is non zero the device or interface board is enabled for operation online If v is zero it is reset offline After a device or an interface board is taken offline the handle ud is no longer valid Before accessing the board or device again you must re execute an ibfind or ibdev call to open the board or device Calling ibonl with v non zero restores the default configuration settings of a device or interface board Device Function Example 1 Disable the device plotter ibonl plotter 0 2 Enable the device plotter after taking it offline temporarily plotter ibfind plotter 3 Restore default configuration settings of the device plotter ibonl plotter 1 National Instruments Corp 5 55 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBONL 3 continued IBONL 3 Board Function Examples 1 Disable the interface board brdo ibonl brd0 0 2 Enable the interface board brdo brd0 ibfind gpib0 3 Restore default conf
87. SUB 3A 072 58 MLA26 1B 033 27 ESC 3B 073 59 MLA27 1C 034 28 FS 3C 074 60 lt MLA28 1D 035 29 GS 3D 075 61 MLA29 IE 036 30 RS 3E 076 62 gt MLA30 1F 037 31 US 3F 077 63 UNL Message Definitions DCL Device Clear MSA My Secondary Address GET Group Execute Trigger MTA My Talk Address GTL Go To Local PPC Parallel Poll Configure LLO Local Lockout PPD Parallel Poll Disable MLA My Listen Address NI 488 2M Reference Manual A 2 National Instruments Corp Appendix Multiline Interface Messages Multiline Interface Messages Hex Oct Dec ASCH Msg Hex Oct Dec ASCH Msg 40 100 64 MTAO 60 140 96 MSAO PPE 41 10 65 A MTAI 61 141 97 a MSA1 PPE 42 102 66 B MTA2 62 142 98 b MSA2 PPE 43 100 67 MTA3 63 143 99 c MSA3 PPE 44 104 68 D MTA4 64 144 100 d 4 45 105 69 E MTAS 65 145 101 e MSAS PPE 46 106 70 MTA6 66 146 102 f MSA6 PPE 47 107 71 MTA7 67 147 103 g MSA7 PPE 48 10 72 H 68 150 104 h MSA8 PPE 49 11 73 I MTA9 69 151 105 i MSA9 PPE 4A 112 74 J MTAIO 152 106 j MSA10 PPE 4B 113 75 11 6B 153 107 k MSA11 PPE 4C 114 76 L MTAI2 6 154 108 MSA12 PPE 4D 115 77 M MTAI3 6 155 100 m MSA13 PPE 4E 116 78 MTAI4 6E 156 110 n MSA14 PPE 4F 117 79 15 6F 157 111 o MSA15 PPE 50 120 80 P MTAI16 70 160 112 p MSA16 PPD 51 121 81 MTAI7 71 161 113 q MSA17 PPD 52 122 82 MTAI8 72 162 114 r MSA18 PPD 53 123 83 S 19 73 163 115 s MSA19 PPD 54 124 84 T MTA20 74 164 116 t MSA20 PPD 55 12
88. Test for Remote Enable REN main int clines E IE if gpibO ibfind gpib0 lt 0 error ibsta iblines gpib0 amp clines lt 0 error clines amp 0 10 printf GPIB board can t monitor REN exit clines amp 0 1000 printf is asserted exit printf REN is not asserted National Instruments Corp 5 49 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBLLO 3 IBLLO 3 Purpose Place device in Local Lockout state Syntax int ibllo intud ud is a file descriptor returned from an ibfind call The 11 function sends the message LLO which places a device in the Local Lockout state This usually inhibits recognition of front panel input All devices are unaddressed ibllo sends the following commands and information e Listen address of the device e Secondary address of the device if applicable e Local Lockout LLO e Unlisten Refer also to IBCMD Device Function Example Place device vmtr in Local Lockout state ibllo vmtr NI 488 2M Reference Manual 5 50 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBLN 3 IBLN 3 Purpose Check for the presence of a device on the bus Syntax int ibln int ud int pad int sad short listen ud is a board or device descriptor pad legal values are 0 to 30 specifies the primary G
89. a device ibtrg addresses and triggers the specified device ibtrg sends the following commands Talk address of access board Secondary address of access board if applicable Unlisten Listen address of the device Secondary address of the device if applicable Group Execute Trigger GET Other command bytes may be sent as necessary Refer to IBCMD for additional information Device Function Example Trigger the device analyz ibtrg analyz NI 488 2M Reference Manual 5 82 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBWAIT 3 IBWAIT 3 Purpose Wait for selected event Syntax int ibwait int ud int mask ud specifies a device or an interface board mask is a bit mask with the same bit assignments as the status word ibsta ibwait is used to monitor the events selected by the bits in mask and to delay processing until any of them occur These events and bit assignments are shown in Table 5 10 The declaration file for C defines the mnemonic for each bit in the status bytes ibsta and iberr For example the following two calls are equivalent if ibsta amp tacs printf talk address if ibsta 0x8 printf talk address Table 5 10 Wait Mask Layout Hex s Device requesting servis 80 GPIB board is inocu ware 0 GPIB board is Controller In Charge Attention is asserted continues National Instruments Corp 5 83 NI 488
90. a device at talk address hex 52 ASCII R using the Serial Poll Enable SPE or hex 18 and Serial Poll Disable SPD or hex 19 commands the GPIB listen address is hex 20 or ASCII lt space gt ibcmd brd0 R 18 4 TAD MLA SPE ibrd brd0 rd 1 read one byte ibcmd brd0 x19_ 2 SPD UNT National Instruments Corp 5 25 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBCONFIG 3 IBCONFIG 3 Purpose Change the software configuration parameters Syntax int ibconfig intud int option int value ud designates a board or device unit descriptor option selects the software configuration item value is the current value to which the selected configuration item is to be changed ibconfig alters the current value of the configuration item to the value for the selected board or device opt ion may be any of the defined constants in Table 5 4 and value must be valid for the parameter that you are configuring The previous setting of the configured item is returned in iberr An EARG error results if option or value is not valid An ECAP error results if the driver is not able to make the requested change If ud is invalid or the NI 488 2M driver is not installed an EDVR error results Device Function Example Enable unaddressing of device dev1 at the end of I O operation ibconfig devl IbcUnAddr 1 Board Function Examples Enable automatic serial polling of boar
91. a new udx prompt and the EARG error invalid function argument The following example illustrates this case ibdev 0 66 0x67 7 1 0 8100 err cmpl error EARG 6 previous value 16 If the ibdev call returns with an EARG error it is necessary to identify which parameters are incorrect and use the appropriate command to fix it In Example 4 the pad is wrong and can be fixed with an ibpad call NI 488 2M Reference Manual 6 6 National Instruments Corp Chapter 6 ibic Note The ibdev call should not be used until after all 3b ind calls have been made for devices This is to ensure that ibdev does not choose a device that may later be used with an ibfind call In addition all device descriptors are valid until they are explicitly taken offline by an ibonl 0 call Therefore it is important to place all devices offline at the end of an application in order to ensure that ibdev functions correctly in subsequent applications Using ibwrt The ibwrt command sends data to a GPIB device For example to send the six character data string F3R5T1 from the computer to a device called dev1 you enter the following string at the dev1 prompt dev1 ibwrt F3R5T1 0100 cmp1 count 6 The returned Status Word 0100 indicates a successful I O completion while the Byte Count indicates that all six characters were sent from the computer and received by the device Using ibrd The ibrd command causes a GP
92. about the device address The default primary address of all GPIB boards is 0 There are no hardware switches on the GPIB interface board to select the GPIB address Secondary GPIB Address Any device or board using extended addressing must be assigned a secondary address in the range from hex 60 to hex 7E 96 to 126 decimal or the option NONE can be selected to disable secondary addressing As with primary addressing the secondary GPIB address of a device is set within that device either with hardware switches or a software program This address and the address listed in ibconf must correspond Refer to the device documentation for instructions about secondary addressing Secondary addressing is disabled for all boards and devices unless changed in ibconf The default option for this characteristic is NONE Timeout Settings The timeout value is the approximate minimum length of time that I O functions such as ibrd ibwrt and ibcmd can take before a timeout occurs It is also the length of time that the ibwait function waits for an event before returning if the TIMO bit is set in the event mask If the SRQI bit and TIMO bit in the event mask are passed to the ibwait function and no SRQ is detected the function will timeout Refer to the IBWAIT function description in Chapter 3 Understanding the NI 488 2M Software and Chapter 4 NI 488 2M Software Characteristics and Routines of this manual for more information This field in ib
93. addresslist is array of address integers of any size terminated by the value NOADDR Example Instruct two devices connected to board 0 whose GPIB addresses are 8 and 9 to perform their self tests Addr4882 t addresslist 3 8 9 NOADDR short resultlist 2 TestSys 0 addresslist resultlist National Instruments Corp 4 33 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 Trigger 3 Trigger 3 Purpose Trigger a single device Syntax void Trigger int board Addr4882_t address board specifies a board number The GPIB Group Execute Trigger message is sent to the device at the given address The parameter address contains in its low byte the primary GPIB address of the device to be cleared The high byte should be 0 if the device has no secondary address Otherwise it should contain the desired secondary address If the address is NOADDR the Group Execute Trigger message is sent with no addressing thereby triggering all previously addressed Listeners The Trigger routine is used to trigger exactly one GPIB device To send a single message that triggers several particular GPIB devices use the TriggerList function Example Trigger a digital voltmeter connected to board 0 whose primary GPIB address is 9 and whose secondary GPIB address is 97 Trigger 0 MakeAddr 9 97 In C a macro has been defined in the header file ugpib h MakeAddr p s which can be
94. al 3 6 National Instruments Corp Chapter 3 CMPL dev brd LOK brd REM brd CIC brd ATN brd Understanding the NI 488 2M Software asserted in the serial poll status byte of the device The serial poll that obtains the status byte may be the result of an ibrsp or the poll may be done automatically by the driver if automatic serial polling is enabled RQS is cleared when an ibrsp reads the serial poll status byte that caused the RQS An ibwait on RQS should only be done on devices that respond to serial polls CMPL indicates the condition of outstanding I O operations It is set in the status word whenever I O is complete CMPL is cleared while I O is in progress LOK indicates whether the board is in a lockout state While LOK is set the EnableLocal routine or ibloc function is inoperative for that board LOK is set whenever the GPIB board detects the Local Lockout LLO message has been sent either by the GPIB board or by another Controller LOK is cleared when the Remote Enable REN GPIB line becomes unasserted by the System Controller REM indicates whether or not the board is in the remote state REM is set whenever the Remote Enable REN GPIB line is asserted and the GPIB board detects that its listen address has been sent either by the GPIB board or by another Controller REM is cleared whenever REN becomes unasserted or when the GPIB board as a Listener detects the Go to Local GTL command has be
95. al for accidental injury caused by product failure or by errors on the part of the user or application designer Any use or application of National Instruments products for or involving medical or clinical treatment must be performed by properly trained and qualified medical personnel and all traditional medical safeguards equipment and procedures that are appropriate in the particular situation to prevent serious injury or death should always continue to be used when National Instruments products are being used National Instruments products are NOT intended to be a substitute for any form of established process procedure or equipment used to monitor or safeguard human health and safety in medical or clinical treatment Contents About This Manual roD bp xiii Organization of This Manual eee xiii Conventions Used in This Manual eee xiv Customer Communication cc cecesseeececeeceseeececeeeesseeeneceneeeees XV Chapter 1 Introduction Mab dein MD REA UH 1 1 Introduction to the GPIB 1 1 History of the GPIB tte eei 1 1 Backero nd iere et ete e 1 1 2 Installation and Configuration of NI 488 2M a ai omen 2 1 Software Installation enne nennen 2 1 Software Configuration 2 1
96. ansfer between the GPIB board and memory in which the CPU moves each data byte according to program instructions See DMA NI 488 2M Reference Manual G 8 National Instruments Corp R REN or remote enable root directory S SCPI SCSI SDC or selected device clear s serial poll serial poll disable serial poll enable service request source handshake SPD or serial poll disable National Instruments Corp Glossary A GPIB line controlled by the System Controller but used by the CIC to place devices in remote program mode The top level directory on a hard disk Standard Commands for Programmable Instruments Small Computer System Interface bus The GPIB command used to reset internal or device functions of an addressed Listener See DCL and IFC seconds The process of polling and reading the status byte of one device at a time See parallel poll See SPD See SPE See SRQ The GPIB interface function that transmits data and commands Talkers use this function to send data and the controller uses it to send commands See acceptor handshake and handshake The GPIB command used to cancel an SPE command G 9 NI 488 2M Reference Manual Glossary SPE or serial poll enable SRQ or service request startup drive status byte status word system controller Tl TAD or talk address talker TCT or take control timeout NI 488 2M Reference Manual G 10 The GPIB
97. any other function calls that require that capability e fcontrol has been passed with an ibpct call wait for it to be returned with the ibwait function ENOL 2 Error Condition Function detected no Listeners Solutions e Check that the device is powered on and also that at least two thirds of the devices on the GPIB are turned on e Inspect the interconnecting cable to see that the devices are attached and that the connectors are seated properly National Instruments Corp B 1 NI 488 2M Reference Manual Common Errors and Their Solutions Appendix B e Check the switches or control panel of the device and make sure its GPIB address is what you think it is Check also whether the device uses extended addressing and requires a primary and secondary address Some devices use multiple secondary addresses to enable different internal functions e For device write functions run ibconf and check that the address of the device including the secondary address is correct If a change is made restart the system Then run ibic to verify that the address is correct as follows Open the device you want to write to using ibfind and execute ibpad and ibsad calls passing each the address value you believe is correct If secondary addressing is not used pass a value of zero to the ibsad function Assuming these calls do not return with an error ibic will return the previous address value which will be the same as the new one if you ha
98. any size terminated by the value NOADDR If any of the specified devices times out instead of responding to the poll then the error code EABO is returned in iberr and ibcnt contains the index of the timed out device Although the A11Spo11 routine is general enough to serial poll any number of GPIB devices the ReadStatusByte routine should be used in the case of polling exactly one GPIB device Example Serial poll two devices connected to board 0 whose GPIB addresses are 8 and 9 Addr4882 t addresslist 3 8 9 NOADDR short resultlist 2 AllSpoll 0 addresslist resultlist NI 488 2M Reference Manual 4 6 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines DevClear 3 DevClear 3 Purpose Clear a single device Syntax void DevClear int board Addr4882 t address board specifies a board number The GPIB Selected Device Clear SDC message is sent to the device at the given address The parameter address contains in its low byte the primary GPIB address of the device to be cleared The high byte should be 0 if the device has no secondary address Otherwise it should contain the desired secondary address If address contains the constant value NOADDR the Universal Device Clear message is sent to all devices on the GPIB The DevClear routine is used to clear either exactly one GPIB device or all GPIB devices To send a single message that clears several particular GPIB devi
99. apability are not allowed The ibrsc function is used to enable or disable the capability of the GPIB board to send the Interface Clear IFC and Remote Enable REN messages to GPIB devices using the ibsic and ibsre functions respectively The interface board must not be System Controller to respond to IFC sent by another Controller In most applications the GPIB board will always be the System Controller but in some applications the GPIB board will never be the System Controller In either case the ibrsc function is used only if the computer is not going to be System Controller for the duration of the program execution While the IEEE 488 standard does not specifically allow schemes in which System Control can be passed dynamically from one device to another the ibrsc function can be used in such a scheme When ibrsc is called and an error does not occur iberr is set to one if the interface board was previously System Controller and zero if it was not Board Function Examples Request to be System Controller if the interface board brdo is not currently so designated ibrsc brdo 1 National Instruments Corp 5 69 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBRSP 3 IBRSP 3 Purpose Return serial poll byte Syntax intibrsp intud char spr ud specifies a device spr stores the serial poll response The ibrsp function is used to serial poll one device and obtain its st
100. ard that capability by calling ibrsc or by using ibconf to configure that capability into the driver EABO 6 EABO indicates that I O has been canceled usually due to a timeout condition Another cause is receiving the Device Clear message from the CIC NI 488 2M Reference Manual 3 14 National Instruments Corp Chapter 3 ENEB 7 EDMA 8 EBTO 9 ECAP 11 EFSO 12 EBUS 14 Understanding the NI 488 2M Software To remedy a timeout error if I O is actually progressing but times out anyway lengthen the timeout period with ibtmo More frequently however the I O is stuck the Listener is not continuing to handshake or the Talker has stopped talking or the byte count in the call which timed out was more than the other device was expecting Be sure that both parties to the transfer understand what byte count is expected or if possible have the Talker use the END message to assist in early termination ENEB occurs when there is no GPIB board at the I O address specified in the configuration program This happens when the board is not physically plugged into the system the I O address specified during configuration does not match the actual board setting or there is a conflict in the system with the base I O address If there is a mismatch between the actual board setting and the value specified at configuration time either reconfigure the software or change the board switches to match the configured value
101. ary Address e Timeout Setting e EOT e EOS Example 1 shows ibdev opening an available device and assigning it to access gpibO board 0 with a primary address of 6 pad 6 secondary address of hex 67 sad 0x67 a timeout of 10 ms tmo 7 the END message enabled eot 1 and the EOS mode disabled eos 0 Example 1 ibdev 0 6 0x67 7 1 0 id 32006 If you type the following ibdev lt Enter gt the software prompts you for the input parameters as shown in Example 2 National Instruments Corp 6 5 NI 488 2M Reference Manual ibic Chapter 6 Example 2 ibdev enter board index 0 enter primary address 6 enter secondary address 0x67 enter timeout 7 enter EPO on last byte flag 1 enter end of string mode byte 0 id 32006 There are three distinct errors that can occur with the ibdev call e device is available an EDVR error is returned This is also the error that occurs if the specified board index refers to a non existent board that is not 0 or 1 The following example illustrates this case ibdev 4 6 0x67 7 1 0 8000 err error EDVR 1 e Ifthe specified board index refers to a known board such as 0 or 1 but the board cannot be found by the driver an ENEB error is returned In this case run ibconf to insure that the base address of the board is set correctly e foneof the last five parameters is an illegal value the ibdev call returns with
102. ate TIMO dev brd TIMO indicates whether a timeout has occurred TIMO is set in the status word following an ibwait if the TIMO bit of the ibwait mask parameter is also set and if the wait has exceeded the time limit value TIMO is also set following any synchronous I O functions for example ibrd ibwrt ibcmd if a timeout occurs during a call TIMO is cleared in the status word in all other circumstances END dev brd END indicates either that the END message has been received from the EOI line or that the driver is configured to terminate a read function on an EOS byte and that an EOS byte has been received following a read function While the GPIB board is performing a shadow handshake as a result of the ibgts function any other function may return a status word with the END bit set if the END or EOS message occurred before or during that call END is cleared in the status word when any I O operation is initiated SRQI brd SRQI specifies that some device is requesting service SRQI is set in the status word whenever the GPIB board is CIC the GPIB SRQ line is asserted and the automatic serial poll capability is disabled SRQI is cleared whenever the GPIB board ceases to be the CIC or the GPIB SRQ line is unasserted RQS dev RQS appears only in the status word of a device function and indicates that the device is requesting service RQS is set in the status word whenever the hex 40 bit is NI 488 2M Reference Manu
103. ational Instruments Corp G 1 NI 488 2M Reference Manual Glossary B board board function command message configuration controller or controller in charge CPU D data or data message DAV or data valid DCL or device clear NI 488 2M Reference Manual G 2 One of the GPIB interface boards in the computer See device A function that operates on or otherwise pertains to one of the GPIB interface boards in the computer These boards are referred to as gpib0 gpib1 and soon See device function See controller Common term for interface message The process of altering the software parameters in the driver that describe the key characteristics of the devices and boards that are manipulated by the driver By keeping this information such as GPIB address in the driver it does not have to be defined in each application program ibconf is the NI 488M configuration program The device that manages the GPIB by sending interface messages to other devices central processing unit Common term for device dependent message One of the three GPIB handshake lines See handshake The GPIB command used to reset the device or internal functions of all devices See and SDC National Instruments Corp declaration file device device clear device dependent message device function DIO1 through DIO8 DMA or direct memory access driver DVM E
104. atus byte or to obtain a previously stored status byte If bit 6 the hex 40 bit of the response is set the device is requesting service When the automatic serial polling feature is enabled the specified device may have been polled previously If it has been polled and a positive response was obtained the RQS bit of ibsta is set on that device In this case ibrsp returns the previously acquired status byte If the RQS bit of ibsta is not set during an automatic poll it serial polls the device When a poll is actually conducted the specific sequence of events is as follows Unlisten UNL 2 Controllers Listen Address 3 Secondary address of the access board if applicable 4 Serial Poll Enable SPE 5 Talk address of the device 6 Secondary address of the device if applicable 7 Read serial poll response byte from device 8 Serial Poll Disable SPD 9 Other command bytes may be sent as necessary NI 488 2M Reference Manual 5 70 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBRSP 3 continued IBRSP 3 The response byte spr except the RQS bit is device specific For example the polled device might set a particular bit in the response byte to indicate that it has data to transfer and another bit to indicate a need for reprogramming Consult the device documentation for interpretation of the response byte Refer to JBCMD and IBRD for additional information Device
105. atus word are applicable except RQS NI 488 2M Reference Manual 5 64 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBWAIT 3 continued IBWAIT 3 Device Function Example Wait indefinitely for the device logger to request service mask RQS mask 0x800 T ibwait logger mask Board Function Examples 1 Wait for a service request or a timeout mask SRQI TIMO mask 0x5000 x ibwait brd0 mask 2 Update the current status for ibsta ibwait ud 0 3 Wait indefinitely until control is passed from another CIC mask CIC fE CIC 0x20 uA ibwait ud mask 4 Wait indefinitely until addressed to talk or listen by another CIC mask TACS LACS TACS LACS 0x0C ibwait ud mask National Instruments Corp 5 85 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBWRT 3 IBWRT 3 Purpose Write data from string Syntax int ibwrt intud char wrt unsigned long cnt ud specifies a device or an interface board wrt the buffer of data to be sent over the GPIB The ibwrt terminates on any of the following events e All bytes are transferred Anerror is detected e The time limit is exceeded e Device Clear DCL or Selected Device Clear SDC command is received from another device which is the CIC After termination ibcnt is the representation of the number of bytes read A short
106. ble Table Table Table 5 8 5 10 6 1 6 2 6 3 6 5 Contents Figures Upper Level of ibconf sse 2 3 Lower Level of ibconf esee 2 5 Multiboard GPIB System see 3 5 GPIB Connector and the Signal Assignment D 6 Linear Configuration D 7 Star Configuration esee D 8 Tables Timeout Settings 2 10 Status Word ibsta Layout essere 3 7 GPIB Error Codes esee 3 11 Signal Mask Layout sees 3 19 CNI 488 2 ROUDES eet ree restet 4 5 CNI 488 FUNCIONS rebro nenne 5 5 ibask Board Configuration Parameter Options 5 13 ibask Device Configuration Parameter Options 5 18 ibconfig Board Configuration Parameter Options 5 28 ibconfig Device Configuration Parameter Options 5 33 Data Transfer Termination Method 5 39 Parallel Poll Commands sess 5 67 Signal Mask Layout 5 75 Timeout Code Values eee 5 79 Wait Mask Layout esee 5 83 Syntax of GPIB Functions in ibic oo eee 6 10 Syntax for NI 488 2 Routines in ibic 6 11 Status Word Layout ee eee ceeceseeeeeeeceeeeecneeneensees 6 15 Auxiliary Functions That
107. board 0 at address 8 so that it responds to parallel polls on data line 5 with sense 0 assert the line if the individual status is 0 unassert the line if the individual status is 1 PPollConfig 0 8 5 0 National Instruments Corp 4 17 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 PPollUnconfig 3 PPollUnconfig 3 Purpose Unconfigure devices for parallel polls Syntax void PPollUnconfig int board Addr4882 t addresslist board specifies a board number The GPIB devices whose addresses are contained in the address array are unconfigured for parallel polls that is they no longer participate in polls The parameter addresslist isan array of address integers of any size terminated by the value NOADDR If the array contains only the value NOADDR or NULL the GPIB Parallel Poll Unconfigure PPU message is sent unconfiguring all devices Example Unconfigure two devices connected to board 0 whose GPIB addresses are 8 and 9 Addr4882 t addresslist 3 8 9 NOADDR PPollUnconfig 0 addresslist NI 488 2M Reference Manual 4 18 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines RcvRespMsg 3 RcvRespMsg 3 Purpose Read data bytes from already addressed device Syntax void RcvRespMsg int board char data long count int termination board specifies a board number Up to count data bytes are read from the GP
108. boards or devices and must be called before any other NI 488 functions When the software is installed a description of each device is placed in an internal reference table accessible by the driver The ibfind function locates a board or device using the symbolic names defined in the driver such as gpib0 devl or scope To find out the names of these symbols you canrun ibconf Programming Features Common to NI 488 2 Routines and NI 488 Functions This section describes programming characteristics that apply when using either the NI 488 2 routines or the NI 488 functions NI 488 2M Reference Manual 3 4 National Instruments Corp Chapter 3 Understanding the NI 488 2M Software Multiboard Driver The driver can control or manipulate more than one interface board Figure 3 1 shows a multiboard GPIB system with board gpib0O connected to two devices an oscilloscope and a digital voltmeter and with board gpibl connected to two other devices a printer and a plotter This type of driver is commonly called a multiboard driver Boards Devices Another GPIB Figure 3 1 Multiboard GPIB System National Instruments Corp 3 5 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 Learning NI 488 2 and Your Instruments The best way to learn the NI 488 2 routines and NI 488 functions and the commands of your instruments is interactively through your keyboard The Interface Bus Interactive Control ibic program
109. bsta is set iberr isthe first error detected Device IBRD Function If ud specifies a device the device is addressed to talk and the access board is addressed to listen Then the data is read from the device Board IBRD Function If ud specifies an interface board the ibrd function reads from a GPIB device that is assumed to already be properly addressed by the CIC In addition to the termination conditions previously listed a board ibrd function also terminates if a Device Clear DCL or Selected Device Clear SDC command is received from the CIC NI 488 2M Reference Manual 5 62 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBRD 3 continued IBRD 3 If the access board is Active Controller the board is placed in Standby Controller state with ATN off even after the operation completes If the access board is not Active Controller ibrd commences immediately If the board is CIC the ibcmd function must be used prior to ibrd to address a device to talk and the board to listen An EADR error results if the board is CIC but has not been addressed to listen with the ibcmd function An EABO error results if for any reason ibrd does not complete within the time limit Device Function Example Read 100 bytes of data from a device int dvm char rd 100 dvm ibdev 0 10 0 15 1 0 ibra dom Xd 100 Board Function Examples 1 Read 100 bytes of data from a device
110. ce Queues are necessary because some devices can send multiple positive status bytes back to back When a positive response from a device is received the RQS bit of its status word ibsta is set The polling continues until SRQ is unasserted or an error condition is detected If the driver cannot locate the device requesting service no known device responds positively to the poll or if SRQ becomes stuck on because of a faulty instrument or cable a GPIB system error exists that will interfere with the proper evaluation of the RQS bit in the status words of devices The error ESRQ is reported to you if and when you issue an ibwait call with the RQS bit included in the wait mask Should the error condition correct itself you will notice it by calling ibwait with the RQS bit set in the mask where the ESRQ error will not be reported Aside from the difficulty caused by ESRQ in waiting for RQS the error will have no detrimental effects on other GPIB operations If the serial poll function ibrsp is called and one or more responses have been received previously via the automatic serial poll feature the first queued response is returned by the ibrsp function Other responses are read in first in first out FIFO fashion If the RQS bit of the status word is not set when ibrsp is called the function conducts a serial poll and returns whatever response is received If your application requires that requests for service be noticed you should exam
111. ce it there explicitly See Device Example 2 Device Function Example 1 Write ten instruction bytes to the device dvm ibwrt F3R1X5P2GO 10 2 Write five instruction bytes by a carriage return and a linefeed to the device ptr Linefeed is the EOS character of the device ibwrt ptr IP2X5 r n 7 Board Function Examples Write ten instruction bytes to a device at listen address hex 2F ASCII GPIB board talk address is hex 40 ASCII brd0 3 ibwrt brd0 F3R1X5P2G0 10 National Instruments Corp 5 87 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBWRTF 3 IBWRTF 3 Purpose Write data from file Syntax intibwrtf int ud char 1 ud specifies a device or an interface board 1 is the filename from which the data is written 1 is the null terminated UNIX pathname of the file to be sent over the GPIB ibwrtf automatically opens the file On exit ibwrtf closes the file An EFSO error results if it is not possible to open seek read or close the specified file The ibwrtf function operation terminates on any of the following events e All bytes sent Anerror is detected e time limit is exceeded e Device Clear DCL or Selected Device Clear SDC command is received from another device that is the CIC After termination ibcnt is the number of bytes written Device IBWRTF Functi
112. ce may be System Controller and the GPIB board should be designated as not System Controller A no response would designate not System Controller and a yes response would designate System Controller capability In general the GPIB board should be designated as System Controller The default option for this characteristic is yes Disable Auto Serial Polling Board Characteristic Only This option enables or disables automatic serial polls of devices when the GPIB Service Request SRQ line is asserted Positive poll responses are stored following the polls and can be read with the ibrsp device function Refer to Chapter 5 NI 488M Software Characteristics and Functions for further information Normally this feature will not conflict with devices that conform to the IEEE 488 specification If there is a conflict with a device a y response for this field disables this feature The default option for this characteristic is no GPIB Bus Timing Board Characteristic Only This field specifies the T1 delay of the board s source handshake capability This delay determines the minimum interval following RFD after which the board may assert DAV during a write or command operation If the total length of the GPIB cable length in the system is less than 15 m the value of 350 ns is appropriate There are other factors that may affect the choice of the T1 delay although they are unlikely to affect you Refer to the JEEE Std 488 1 1987 Section 5
113. ces use the DevClearList routine Example Clear a digital voltmeter connected to board 0 whose primary GPIB address is 9 and whose secondary GPIB address is 97 DevClear 0 MakeAddr 9 97 In C a macro has been defined in the header file ugpib h MakeAddr p s which can be used to pack the primary and secondary addresses into the correct form National Instruments Corp 4 9 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 DevClearList 3 DevClearList 3 Purpose Clear multiple devices Syntax void DevClearList intboard Addr4882_t addresslist board specifies a board number The GPIB devices whose addresses are contained in the address array are cleared The parameter addresslist is an array for any size of address integers terminated by the value NOADDR Although the DevClearList routine is general enough to clear any number of GPIB devices the DevClear routine should be used in the common case of clearing exactly one GPIB device If the array contains only the value NOADDR or NULL the universal Device Clear message is sent Example Clear two devices connected to board 0 whose GPIB addresses are 8 and 9 Addr4882_t addresslist 3 8 9 NOADDR DevClearList 0 addresslist NI 488 2M Reference Manual 4 10 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines EnableLocal 3 EnableLocal 3 Purpose
114. command used to enable a specific device to be polled That device must also be addressed to talk See SPD The GPIB line that a device asserts to notify the CIC that the device needs servicing The hard disk that is used to start up the computer The data byte sent by a device when it is serially polled Same as ibsta See ibsta The single designated controller that can assert control become CIC of the GPIB by sending the Interface Clear IFC message Other devices can become CIC only by having control passed to them A GPIB timing parameter primarily associated with the data settling time that is the time in which new bytes on the DIO lines are allowed to settle before the DAV signal is asserted T1 ranges from 350 ns to above 2 us See MTA A GPIB device that sends data messages to listeners The GPIB command used to pass control of the bus from the current Controller to an addressed Talker A feature of the NI 488 2M driver that prevents I O functions from hanging indefinitely when there is a problem on the GPIB National Instruments Corp TTL ud ULI unit descriptor UNL or unlisten UNT or untalk Glossary An integrated circuit that implements most of the GPIB Talker Listener and Controller functions in hardware transistor transistor logic A variable name and first argument of each function call that contains the unit descriptor of the GPIB interface board or other GPIB device
115. conf ibconf operates at both an upper and a lower level The upper level consists of the board device maps and gives a graphical picture of the GPIB system as defined in the driver The lower level consists of screens describing the individual board and devices that make up the system NI 488 2M Reference Manual 2 2 National Instruments Corp Chapter 2 Installation and Configuration of NI 488 2M Software Upper Level Device Map for Board GPIBx Figure 2 1 shows the upper level of ibconf National Instruments Device Map for SCSI GPIBO SPARCstation 1 gpibO Use cursor keys h j k amp 1 to select a device or board Use control keys below to select desired action Use B F to display maps for other boards 0 devil 1 0 dev5 E dev9 m 0 dev13 0 dev2 0 dev6 0 10 0 devi4 0 dev3 0 dev7 0 devil m 0 dev15 L0 dev4 0 dev8 0 dev12 0 devi16 Q help R rename T dis connect I edit O exit Figure 2 1 Upper Level of ibconf As shown in Figure 2 1 the upper level screen of ibconf displays the names of all devices controlled by the driver It also indicates which devices if any are accessed through the interface or access board named gpibx where x is 0 or for the two board driver You can move around the map by using the cursor control keys The followi
116. conf is set to a code mnemonic which specifies the time limit as shown in Table 2 1 National Instruments Corp 2 9 NI 488 2M Reference Manual Installation and Configuration of NI 488 2M Software Chapter 2 Table 2 1 Timeout Settings cue ee Code Value Timeout nm 1 mms 2 now 3 mew a um s ue mms s 30m noms o 100m Tf you select TNONE no limit will be in effect and I O operations could proceed indefinitely The default option for this characteristic is T10s EOS byte You can program some devices to terminate a read operation when a selected character is detected A linefeed character hex is a common EOS byte NI 488 2M Reference Manual 2 10 National Instruments Corp Chapter 2 Installation and Configuration of NI 488 2M Software Note The driver does not automatically append an EOS byte to the end of data strings on write operations You must explicitly include this byte in your data string The designation of the EOS byte is only for the purpose of informing the driver of its value so that I O can terminate correctly The default option for this characteristic is OOH Terminate READ on EOS Some devices send an EOS byte signaling the last byte of a data message A yes response to this field causes the GPIB board to terminate a read operation when it receives the EOS byte The default option for this
117. count can occur on any of the above terminating events but the first When the device ibwrt function returns ibsta holds the latest device status ibcnt is the number of data bytes written and if the ERR bit in ibsta isset iberr is the first error detected Device IBWRT Function If ud specifies a device the device is addressed to listen and the access board is addressed to talk Then the data is written to the device Board IBWRT Function If ud specifies an interface board the ibwrt function attempts to write to a GPIB device that is assumed to be already addressed by the CIC NI 488 2M Reference Manual 5 66 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBWRT 3 continued IBWRT 3 If the access board is ibcmd must be called prior to ibwrt to address the device to listen and the board to talk If the access board is Active Controller the board is first placed in Standby Controller state with ATN off even after the write operation completes If the access board is not the Active Controller ibwrt commences immediately An EADR error results if the board is CIC but has not been addressed to talk with ibcmd EABO error results if for any reason ibwrt does not complete within the time limit An ENOL error occurs if there are no Listeners on the bus when the data bytes are sent Note If you want to send an EOS character at the end of your data string you must pla
118. cteristics and Functions Chapter 5 IBASK 3 continued IBASK 3 Table 5 2 ibask Board Configuration Parameter Options Continued Options Options Constants Values Returned Information IbaReadAdjust 0x0013 0 Read operations do not have pairs of bytes swapped 1 Read operations have each pair of bytes swapped IbaWriteAdjust 0 Write operations do not have pairs of bytes swapped 1 Write operations have each pair of bytes swapped IbaSendLLO 0 0017 zero The GPIB LLO command is not sent when a device is put online ibfind or ibdev non zero The LLO command is sent IbaPPollTime 0 The board uses the standard duration 2 us when conducting a parallel poll 1 to 17 The board uses a variable length duration when conducting a parallel poll The duration values correspond to the ibtmo timing values IbaEndBitIsNormal 0x001A zero The END bit of ibsta is set only when EOI or EOI plus the EOS character is received If the EOS character is received without EOI the END bit is not set non zero The END bit is set whenever EOI EOS or EOI plus EOS is received continues NI 488 2M Reference Manual 5 16 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBASK 3 continued IBASK 3 Table 5 2 ibask Board Configuration Parameter Options Continued Options Options Constants Values Returned Information IbaSignalNumber 0x001C T
119. cteristics and Routines Chapter 4 ReceiveSetup 3 ReceiveSetup 3 Purpose Prepare a particular device to send data bytes and prepare the GPIB interface board to read them Syntax void ReceiveSetup int board Addr4882_t address board specifies a board number The indicated GPIB device is addressed as a Talker and the indicated board is addressed as a Listener Following this routine it is common to call a routine such as RcvRespMsg to actually transfer the data from the Talker This routine is useful to initially address devices in preparation for receiving data followed by multiple calls of RcvRespMsg to receive multiple blocks of data thus eliminating the need to re address the devices between blocks Alternatively the Receive routine could be used to send the first data block followed by RcvRespMsg for all the subsequent blocks Example Prepare a GPIB device at address 8 to send data bytes to board 0 Then receive messages of up to 100 bytes from the device and store it in a string The message is to be terminated with END char message 100 ReceiveSetup 0 8 RcvRespMsg 0 message 100 STOPEND NI 488 2M Reference Manual 4 22 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines ResetSys 3 ResetSys 3 Purpose Initialize a GPIB system on three levels Syntax void ResetSys int board Addr4882_t adddresslist board specifies a board number The GPIB sys
120. ctions are used The following functions are available at the lower level e Change Characteristics e Change Board or Device e Explain Field e Help e Reset Value e Return to Map Change Characteristics To change a specific characteristic of a device or a board move the cursor onto that characteristic You can also press K Up Arrow or J Down Arrow to move around the characteristics of a device or a board When the cursor is on the characteristic either use the left right arrow keys to select between different options or input the option directly from the keyboard Instructions in the top left hand corner of the screen inform you which method is appropriate for the selected characteristic As you move from entry to entry text appears on the top left hand side of the screen to assist you in making the correct choices NI 488 2M Reference Manual 2 6 National Instruments Corp Chapter 2 Installation and Configuration of NI 488 2M Software Help Press lt Control Q gt to access the comprehensive online help feature of ibconf The help information describes the functions and common terms associated with the lower level of ibconf Explain Field Press lt Control W gt to get an explanation of the field in which you are working Reset Value Press lt Control Y gt to reset a characteristic option to its default value Return to Map At the lower level lt Control O gt returns you to the upper level device map
121. d ibconfig brd0 IbcAUTOPOLL 1 NI 488 2M Reference Manual 5 26 National Instruments Corp Chapter 5 IBCONFIG 3 NI 488M Software Characteristics and Functions continued IBCONFIG 3 Table 5 4 lists the options you can use with ibconfig when ud is a board descriptor or a board index The following is an alphabetical list of the option constants included in Table 5 4 Constants IbcAUTOPOLL IbcCICPROT IbcDMA IbcEndBitIsNormal IbcEOSchar IbcEOScmp IbcEOSrd IbcEOSwrt IbcEOT IbcHSCableLength IbcIRQ IbcPAD Values 0x0007 0x0008 0x0012 Ox001A Ox000F 0x000E 0x000C 0x000D 0x0004 0x001F 0x0009 0x0001 National Instruments Corp 5 27 Constants IbcPP2 IbcPPC IbcPPollTime IbcReadAdjust IbcSAD IbcSC IbcSendLLO IbcSignalNumber IbcSRE IbcTIMING IbcTMO IbcWriteAdjust Values 0x0010 0x0005 0x0019 0x0013 0x0002 0x000A 0x0017 0x001C 0x000B 0x0011 0x0003 0x0014 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBCONFIG 3 continued IBCONFIG 3 Table 5 4 ibconfig Board Configuration Parameter Options Options Options Constants Values Legal Values IbcPAD 0 0001 Changes the primary address of the board Identical to ibpad Default determined by ibconf IbcSAD 0x0002 Changes the secondary address of the board Identical to ibsad Default determined by ibconf IbcTMO 0 0003 Changes the I O timeout limit
122. d ibpad programs the board to respond to the address indicated by Refer also to JBSAD and IBONL National Instruments Corp 5 57 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBPAD 3 continued IBPAD 3 Device Function Example Change the primary GPIB address of plotter to hex A ibpad plotter 0xA Board Function Examples Change the primary GPIB address of the board to hex 7 ibpad brd0 0x7 NI 488 2M Reference Manual 5 58 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBPCT 3 IBPCT 3 Purpose Control Syntax int ibpct int ud ud specifies a device The ibpct function passes CIC authority to the specified device from the access board assigned to that device The board automatically goes to Controller Idle State CIDS The function assumes that the device has Controller capability ibpct calls the board ibcmd function to send the following commands e Unlisten e Listen address of the access board e Talk address of the device e Secondary address of the device if applicable e Control TCT Other command bytes may be sent as necessary Refer to JBCMD for additional information Device Function Example Pass control to the device ibmxt ibpct ibmxt National Instruments Corp 5 59 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5
123. d Interface Clear 130 empl cic atn gpibO Repeat ibsic 130 empl cic atn 9 Repeat ibsic again 130 empl cic atn Turn OFF Display The function causes the NI 488 function output not to display on the screen This function is useful when you want to repeat a NI 488 I O function quickly without waiting for screen output to be displayed Turn ON Display The function causes the display to be restored The following example shows how the and functions are used Twenty four consecutive letters of the alphabet are read from a device using three ibrd calls dev1 ibrd 8 4100 end cmpl COUNT 8 61 62 63 64 65 66 67 68 abcdefgh devi dev1 ibrd 8 devi dev1 ibrd 8 4100 end cmpl COUNT 8 71 72 73 74 75 767778 qrstuvwx NI 488 2M Reference Manual 6 18 National Instruments Corp Chapter 6 ibic n Repeat Function n Times The n function repeats the execution of the specified function n times where n is an integer In the following example the message Hello goes to the printer five times printer 5 ibwrt Hello The function name can be replaced with the function Thus if this example is done the following way the word Hello goes to the printer 20 more times then 10 more times printer 20 printer 10 Notice that the multiplier does not become part of the function name thatis ibwrt Hello isrepeated 20 times not 5 ibwrt
124. d called at the beginning of your application program Refer to Chapter 4 NI 458 2M Software Characteristics and Routines and Chapter 5 NI 488M Software Characteristics and Functions of this manual for more explanations of ibfind Dis connect Press lt Control T gt to logically connect or disconnect a device from a board Move the cursor to the device that is to be connected or disconnected by using the cursor control keys and press lt Control T gt NI 488 2M Reference Manual 2 4 National Instruments Corp Chapter 2 Installation and Configuration of NI 488 2M Software Edit Use lt Control I gt to edit or examine the characteristics of a particular board or device Move to the board or device that you wish to edit using the cursor control keys and press the lt Control I gt key This step puts you in the lower level of ibconf and lists the characteristics for the particular board or device that you wish to edit To exit edit press lt Control O gt Exit Press Control Q to exit ibconf If you have made changes and have pressed Control Q to exit ibconf displays the prompt Save current configuration Type a y yes to save changes or n no to lose changes For more information refer to the Exiting ibconf section later in this chapter Lower Level Device Board Characteristics Figure 2 2 shows the lower level of ibconf National Instruments Board Characteristics SPARCstation 1 B
125. d from the distribution disk to the appropriate subdirectory depending on which interface board you have during installation Note User inputs must be followed by pressing lt Enter gt User inputs are italicized in all the examples in this section National Instruments Corp 6 1 NI 488 2M Reference Manual ibic Chapter 6 To run ibic change the directory to this subdirectory and enter ibic at the prompt as follows SYSTEMS ibic National Instruments Interface Bus Interactive Control Program ibic Copyright c 1985 1996 National Instruments Inc All Rights Reserved Type help for help Messages about the HELP ibfind SET commands appear on the screen The first input prompt to ibic is a colon Using NI 488 2 Routines The SET function is used to select the NI 488 2 function mode The syntax for this form of the SET command is set 488 2 n where n represents a board number for example n 1 for gpib1 Note default value of n is 0 gpib0 Other board indexes can be used here also After issuing this form of the SET command ibic uses the 488 2 prompt to remind you that you are in NI 488 2 mode on board n as follows set 488 2 1 488 2 1 After issuing the set 488 2 command any of the NI 488 2 routines can be used The syntax of the NI 488 2 routines is shown in Table 6 2 NI 488 2M Reference Manual 6 2 National Instruments Corp Chapter 6 ibic Us
126. d to place that device or interface board offline If the ibfind call fails a negative number is returned in place of the unit descriptor The most probable reason for a failure is that the string argument passed into ibfind does not exactly match the default or configured device or board name NI 488 2M Reference Manual 5 44 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBFIND continued IBFIND Device Function Example Assign the unit descriptor of the device named dev 4 Device number 4 to dvm if dvm ibfind dev4 amp ERR error Board Function Examples Assign the unit descriptor of the board gpib0 to int brd0 brdO0 ibfind gpib0 if brd0 amp ERR error National Instruments Corp 5 45 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBGTS 3 IBGTS 3 Purpose from Active Controller to Standby Syntax int ibgts intud int v ud specifies an interface board If v is non zero the GPIB board shadow handshakes the data transfer as an Acceptor and when the END message is detected the GPIB board enters a Not Ready For Data NRFD handshake holdoff state on the GPIB If v is zero no shadow handshake or holdoff is done The ibgts function makes the GPIB board go to the Controller Standby state and to unassert the ATN signal if it initially is the Active Controller ibgts permits t
127. ddress of the plotter with primary address 7 G Now that the plotter is addressed to send its status byte and the board is addressed to receive it the ibrd function is called to read the byte and store it in the variable status The final ibcmd function completes the poll by sending the command string consisting of two messages Serial Poll Disable x19 hex 19 and Untalk _ You can see that a high level device function is easier to use However if an application requires a more complex serial poll routine than the one just described such as one that polls several devices in succession and has other National Instruments Corp 3 3 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 servicing operations at the same time board functions can be used to create such a routine Opening Boards and Devices The first step when using an NI 488 function is to obtain the unit descriptor for all boards and devices that will be used The unit descriptor ud is the general reference to the board or device descriptor returned by the ibfind function or the ibdev function A unit descriptor of a device as the first argument in a function specifies a device function A unit descriptor of a board as the first argument in a function specifies a board function Some NI 488 functions may be both a board function and a device function IBFIND board or devname dev ibfind returns a unit descriptor associated with the name of
128. dresslist result Determine which device is PassControl board address Pass control to another device with Controller capability PPoll board result Perform a parallel poll PPollConfig board address Configure a device for dataline sense parallel polls PPollUnconfig board addresslist Unconfigure devices for parallel polls RcvRespMsg board data termination Read data bytes from already addressed device ReadStatusByte board address Serial poll a single device result to get its status byte Receive board address count Read data bytes from a termination GPIB device ReceiveSetup board address Prepare a particular device to send data bytes and prepare the GPIB board to read them ResetSys board addresslist Initialize a GPIB system on three levels Send board address data eotmode Send data bytes to a single GPIB device SendCmds board commands count Send GPIB command SendDataBytes board data count Send data bytes to already eotmode addressed devices continues NI 488 2M Reference Manual 4 6 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines Table 4 1 C NI 488 2 Routines Continued SendIFC board Clear the GPIB interface functions with IFC SendList board addresslist data Send data bytes to count eotmode multiple GPIB devices SendLLO board Send the local lockout message to all devices SendSetup board addresslist Prepare particula
129. driver 2 1 software installation 2 1 National Instruments Corp Index 15 488 2 Reference Manual Index source handshake capability 2 12 SRQ 2 9 2 12 5 2 to 5 3 5 4 to 5 5 D 4 line 3 16 4 7 stuck 5 3 5 4 SRQI 2 9 3 7 3 8 3 19 5 4 Standard Commands for Programmable Instrumentation See SCPI standby 5 6 star configuration D 8 status bit 5 6 status byte 4 6 status words 3 6 to 3 11 See also ibsta STOPend 3 17 synchronous I O functions 3 8 system control 5 6 system controller 2 5 2 8 2 12 3 9 3 14 5 2 D 2 T T1 delay 2 12 TACS 3 7 3 10 3 11 3 19 talk address 2 9 3 10 3 14 talker 3 19 D 1 to D 2 TCT 3 13 terminate READ on EOS 2 11 terminating a read operation 2 11 TestSRQ 4 7 4 32 6 12 TestSys 4 7 4 33 6 12 time limit 5 6 on I O and wait function calls 2 8 timeout 3 8 3 15 4 5 code values 5 79 I O 4 5 serial polls 4 5 settings 2 5 2 9 to 2 10 timeout settings 2 5 2 9 to 2 10 timeout value See timeout settings TIMO 2 9 3 7 3 8 Trigger 4 7 4 34 6 12 trigger device 5 6 TriggerList 4 7 4 35 6 12 type of compare on EOS 2 11 NI 488 2M Reference Manual Index 16 National Instruments Corp Index U ugpib h 3 18 unit descriptor 3 4 3 12 5 1 UNIX 4 7 UNIX error code 3 12 UNIX signal 2 5 2 13 unlisten 3 10 3 13 untalk 3 10 upper level device map for board GPIBx 2 3 See also ibconf wait mask 5
130. e of one 1 indicates that the corresponding condition is in effect A bit value of zero indicates that the condition is not in effect Table 3 1 lists the conditions and the bit position to be tested for each condition Some bits are set only on device functions dev some bits are set only on board functions brd and some bits are set on either type dev brd The NI 488 2 routines are considered board functions Table 3 1 Status Word ibsta Layout mm ES Mnemonics Pos Value Type Description TMO The declaration file ugpib h for C defines the mnemonic for each bit in the status bytes ibsta and iberr For example the following two calls are equivalent if ibsta amp TACS printf TALK ADDRESS n if ibsta amp 0x0008 printf TALK ADDRESS Wn National Instruments Corp 3 7 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 A description of each status word and its condition follows ERR dev brd ERR is set in the status word following any call that results in an error the particular error may be determined by examining the iberr variable ERR is cleared following any call that does not result in an error Note Itis recommended that you check for an error condition after each call An unnoticed error occurring early in your application program may not become apparent until a later instruction At that time the error can be more difficult to loc
131. e lower eight bits of result are affected Each bit of the poll result returns one bit of status information from each device that has been configured for parallel polls The state of each bit 0 or 1 and the interpretation of these states are based on the latest parallel poll configuration sent to the devices and the individual status of the devices Example Perform a parallel poll on board 0 short result PPoll 0 amp result NI 488 2M Reference Manual 4 16 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines PPollConfig 3 PPollConfig 3 Purpose Configure a device for parallel polls Syntax void PPollConfig int board Addr4882 t address int dataline int sense board specifies a board number The GPIB device at address is configured for parallel polls according to the dataline and sense parameters dataline is the data line 1 8 on which the device is to respond and sense indicates the condition under which the data line is to be asserted or unasserted The device is expected to compare this sense value 0 or 1 to its individual status bit and respond accordingly Devices have the option of configuring themselves for parallel polls in which case they are to ignore attempts by the Controller to configure them You should determine whether the device is locally or remotely configurable before using PPollConfig PPollUnconfig Example Configure a device connected to
132. e purpose of each function or use the online help available in ibic The Application Program When you decide to write your application program refer to Chapter 4 NI 488 2M Software Characteristics and Routines and Chapter 5 NI 488M Software Characteristics and Functions of this manual for the proper syntax of the functions Use ibic to test the sequence of commands your application program uses NI 488 2M Reference Manual 2 14 National Instruments Corp Chapter 3 Understanding the NI 488 2M Software This chapter introduces you to two of the programming options of the NI 488 2M software Specifically the NI 488 2 routines and NI 488 functions are presented to guide you as to which function set to use e NI 488 2 routines directly adhere to the Controller sequences and protocols defined in the IEEE 488 2 1992 standard They accept a single device address or a list of device addresses as an input parameter so that functions can address multiple instruments easily These routines give you all the advantages of IEEE 488 2 e The NI 488 functions have existed for many years and are the industry standard functions for GPIB applications They have both high level device functions and low level board functions This chapter also discusses programming issues such as global variables error codes read and write termination and C programming preparations that are common to both the NI 488 2 routines and NI 488 functions Int
133. e used to program a representative IEEE 488 instrument from your personal computer using the NI 488 functions The applications are written in C The target instrument is a digital voltmeter DVM This instrument is otherwise unspecified that is it is not a DVM manufactured by any particular manufacturer The purpose here is to explain how to use the driver to execute certain programming and control sequences and not how to determine those sequences Because the instructions that are sent to program a device as well as the data that might be returned from the device are called device dependent messages the format and syntax of the messages used in this example are unique to this device Furthermore the interface messages or bus commands that must be sent to each device will also vary but to a lesser degree The exact sequence of messages to program and to control a particular device are contained in its documentation For example the following sequence of actions is assumed to be necessary to program this DVM to make and return measurements of a high frequency AC voltage signal in the autoranging mode 1 Initialize the GPIB interface circuits of the DVM so that it can respond to messages 2 Place the DVM in remote programming mode and turn off front panel control 3 Initialize the internal measurement circuits 4 Instruct the meter to measure volts alternating current VAC using auto ranging AUTO to wait for a trigger from
134. ed and its status byte is placed into the variable result Example Serial poll the device at address 8 and return its status byte short result ReadStatusByte 0 8 amp result NI 488 2M Reference Manual 4 20 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines Receive 3 Receive 3 Purpose Read data bytes from a GPIB device Syntax void Receive intboard Addr4882 t address char data unsigned long count int termination board specifies a board number The indicated GPIB device is addressed and up to count data bytes are read from that device and placed into the pre allocated string data The count value is of type long Even though it is a long value in these languages however integer values and variables may also be passed termination is a value used to describe the method of signaling the end of the data If it is a value between 0 and hex OOFF the ASCII character with the corresponding hex value is considered the termination character and the read is stopped when the character is detected If termination is the constant STOPend defined in the header file ugpib h the read is stopped when END is detected Example Receive 100 bytes from the device at address 8 The transmission should be terminated when END is detected char data 100 Receive 0 8 data 100 STOPend National Instruments Corp 4 21 NI 488 2M Reference Manual NI 488 2M Software Chara
135. ed for that ibwait call and the stuck SRQ state is terminated If the stuck SRQ state is reached at some other time further polls are not attempted until an ibwait for RQS is made at which time the stuck SRQ state is terminated and a new set of NI 488 2M Reference Manual 5 4 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions serial polls is attempted In addition the stuck SRQ state is immediately terminated whenever SRQ is found to be unasserted C NI 488 I O Calls and Functions The most commonly needed I O calls are ibrd and ibwrt In practice ud refers to the board or device to which the command is directed Refer to the JBFIND function description in this chapter and to Chapter 3 Understanding the NI 488 2M Software to determine the type of unit descriptor to use The functions are listed alphabetically by function name in this chapter Tables 5 1 lists the functions and a description of C NI 488 functions respectively Table 5 1 C NI 488 Functions ibask ud option value Return information about software configuration parameters ibbna ud bname ibcac ud v ibclr ud ibemd ud cmd cnt ibconfig ud option value ud ibdev bd_index pad sad tmo eot eos ibdma ud v ibeos ud v ibeot ud v ud ibfind udname National Instruments Corp Change the software configuration parameters Open and initialize an unused device when
136. elieve the National Instruments family of GPIB products for your personal computer will become a valued and integral part of your work environment Introduction to the GPIB The GPIB is a link or interface system through which interconnected electronic devices communicate See Appendix D Operation of the GPIB for more information about GPIB operation History of the GPIB The original GPIB was designed by Hewlett Packard where it is called the HP IB to connect and control programmable instruments manufactured by Hewlett Packard Because of its high data transfer rates of up to 1 Mbyte s the GPIB quickly gained popularity in other applications such as intercomputer communication and peripheral control It was later accepted as the industry standard IEEE 488 The versatility of the system prompted the name General Purpose Interface Bus National Instruments expanded the use of the GPIB among users of computers manufactured by companies other than Hewlett Packard National Instruments specializes both in high performance high speed hardware interfaces and in comprehensive fullly functioning software that helps users bridge the gap between their knowledge of instruments and computer peripherals and of the GPIB itself Background This manual was developed as part of the documentation for the NI 488 2M software Software reference material can be found in this manual Hardware specific information can be found in other documentation prov
137. en sent either by the GPIB board or by another Controller or when the ibloc function is called while the LOK bit is cleared in the status word CIC indicates whether the GPIB board is the Controller In Charge CIC is set whenever the SendIFC routine or ibsic function is executed while the GPIB board is System Controller or when another Controller passes control to the GPIB board CIC is cleared whenever the GPIB board detects Interface Clear IFC from the System Controller or when the GPIB board passes control to another device ATN indicates the state of the GPIB Attention ATN line ATN is set whenever the GPIB ATN line is asserted and cleared when the ATN line is unasserted National Instruments Corp 3 9 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 TACS brd TACS indicates whether the GPIB board has been addressed as a Talker TACS is set whenever the GPIB board detects its talk address and secondary address if enabled has been sent either by the GPIB board itself or by another Controller TACS is cleared whenever the GPIB board detects the Untalk UNT command its own listen address a talk address other than its own talk address or Interface Clear IFC LACS brd LACS indicates whether the GPIB board has been addressed as a Listener LACS is set whenever the GPIB board detects its listen address and secondary address if enabled has been sent either by the GPIB board itself or by anot
138. erence Manual NI 488M Software Characteristics and Functions Chapter 5 Example Program Device Functions include lt stdio h gt include lt stdlib h gt include ugpib h void dvmerr char msg char code device error function void gpiberr char msg gpib error function Application program variables passed to GPIB functions AY char rd 512 read data buffer int device number char spr serial poll response byte main system clear printf READ MEASUREMENT FROM FLUKE 45 n printf lt n Assign a unique identifier to the Fluke 45 that you configured using ibconf exe if dvm ibfind dvm lt 0 gpiberr ibfind Error exit 1 Clear the device if ibclr dvm amp ERR gpiberr ibclr Error exit 1 Write the function range and trigger source instructions to the DVM ibwrt dvm RST VAC AUTO TRIGGER 2 SRE 16 351 if ibsta amp ERR gpiberr ibwrt Error exit 1 Trigger the device and request measurement NI 488 2M Reference Manual 5 92 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions if ibtrg dvm amp ERR gpiberr ibtrg Error exit 1 ibwrt dvm VAL1 51 if ibsta amp ERR gpiberr ibwrt Error exit 1 Wait for the DVM to set RQS or for a timeout if the current time
139. erence Manual NI 488M Software Characteristics and Functions Chapter 5 IBASK 3 continued IBASK 3 Table 5 3 ibask Device Configuration Parameter Options Continued Options Options Constants Values Returned Information IbaReadAdjust 0x0013 0 Read operations do not have pairs of bytes swapped 1 Read operations have each pair of bytes swapped IbaWriteAdjust 0 0014 0 Write operations do not have pairs of bytes swapped Write operations have each pair of bytes swapped IbaSPollTime 0 0018 The length of time the driver waits for a serial poll response when polling the device The length of time is represented by the ibtmo timing values IbaEndBitIsNormal 0x001A zero The END bit of ibsta is set only when EOI or EOI plus the EOS character is received If the EOS character is received without EOI the END bit is not set non zero The END bit is set whenever EOI EOS or EOI plus EOS is received IbaUnAddr Ox001B zero The GPIB commands UNT Untalk and UNL Unlisten are not sent after each device level read and write operation non zero The UNT and UNL commands are sent after each device level read and write IbaBNA 0x0200 The index of the GPIB access board used by the given device descriptor NI 488 2M Reference Manual 5 20 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBBNA 3 IBBNA 3 Purpose Change access board
140. eristics and Functions Chapter 5 if ibrd bd rd 1L amp ERR gpiberr ibrd Error exit 1 if rd 0 0x50 dvmerr Fluke 45 Error rd exit 1 Complete the serial poll by sending the Serial Poll Disable SPD message xf if ibcmd bd 031 1L amp ERR gpiberr ibcmd Error exit 1 Because the DVM and GPIB board are still addressed to talk and listen the measurement can be read as follows f if ibrd bd rd 10L amp ERR gpiberr ibrd Error exit 1 rd ibent 0 printf Reading s n rd Call the ibonl function to disable the hardware and software ibonl bd 0 void gpiberr char msg This routine would notify you that an ib call failed printf Ss n msg printf ibsta amp H x lt ibsta if ibsta amp ERR printf ERR if ibsta amp TIMO printf TIMO if ibsta amp END printf END if ibsta amp SRQI printf SRQI if ibsta amp ROS printf RQS if ibsta amp CMPL printf CMPL if ibsta amp LOK printf LOK if ibsta amp REM printf REM if bsta GIC przrzntt CIC NI 488 2M Reference Manual 5 98 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions if ibsta amp ATN printf ATN if ibsta amp TACS printf TACS if ibsta amp LACS printf LACS if ibsta amp
141. ess of the interface board from its current value to hex 6A ibsad brd0 0x6A 2 Disable secondary addressing for the interface board brdo ibsad brd0 0 0 or Ox7F can be used NI 488 2M Reference Manual 5 74 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBSGNL 3 IBSGNL 3 Purpose Register signal interrupting Syntax void ibsgnl int ud int mask ud is a board descriptor returned from an ibfind call mask is a bit mask with the same bit assignments as the status word ibsta A mask bit is set to request a signal when the corresponding event occurs A mask of zero disables signals Table 5 8 displays the recognized bits Table 5 8 Signal Mask Layout Hex SRQI IEN 100 SRQo LOK 7 GPIB board is in Lockout State REM 6 40 GPIB board is in Remote State CIC 5 20 GPIB board is Controller In Charge TACS 8 GPIB board is Talker LACS GPIB board is Listener DTAS 1 2 GPIB board is in Device Trigger State DCAS 1 GPIB board is in Device Clear State ibsgnl is similar to the ibwait function except that it returns immediately freeing the application program to perform other tasks Except for SRQI DTAS and DCAS a signal will be sent on any transition into or out of the specified state for example from TACS to non TACS The default signal is SIGINT National Instruments Corp 5 75 NI 488 2M Reference Manual NI
142. example 4 37 NI 488 2 routines See NI 488 2 routines NI 488 functions 5 5 to 5 99 program examples See programming with NI 488 functions examples programming 3 18 to 3 20 cable length 2 12 cib c 3 18 CIC 3 7 3 9 3 11 3 13 3 14 3 19 clear device 4 5 5 5 clear GPIB interface functions 4 7 cmd 3 3 CMPL 3 7 3 9 command messages D 1 command operations 2 12 configuration physical D 5 to D 9 linear D 7 star D 8 connecting a device 2 4 control multiple device 4 2 4 3 passing 4 6 5 6 simple device 4 2 4 3 controller 5 2 D 1 to D 2 sequences and protocols 3 1 controller in charge 5 2 D 2 See CIC count variables See ibcnt D DABend 3 17 data lines D 3 data messages D 1 data strings 2 11 DAV 2 12 D 4 DCAS 3 7 3 10 3 11 3 19 default configurations 2 7 default values of the driver 2 8 DevClear 4 5 4 9 6 11 NI 488 2M Reference Manual Index 2 National Instruments Corp Index DevClearList 4 5 4 10 6 11 device address See primary GPIB address device clear 3 10 3 14 3 19 device descriptor 3 4 3 14 device driver 2 14 device functions 3 2 3 3 to 3 4 3 4 3 7 3 15 5 1 to 5 2 example program 5 92 to 5 95 in ibic 6 22 to 6 23 device initialization 4 23 device maps 2 4 See also upper level device map for board GPIBx device names 2 7 device switch settings 3 13 device trigger 3 10 3 19 device write 3 13 device dependent data me
143. for that device A descriptor of the accessed device is one of the function s arguments NI 488 2M Reference Manual 3 2 National Instruments Corp Chapter 3 Understanding the NI 488 2M Software Board Functions In contrast board functions are low level functions that perform rudimentary GPIB operations They are necessary because high level functions may not always meet the requirements of applications In such cases low level functions offer the flexibility to solve your application needs Board functions access the GPIB interface board directly and require you to do the addressing and bus management protocol for the bus A descriptor of the accessed board is one of the function s arguments More About Device and Board Functions You may find it helpful to compare how a high level device function can be replaced by several low level board functions Conducting a serial poll is a good example In the discussion of the ibrsp function the following C example of the device function is used ibrsp pltr status This is equivalent to the following sequence using the board functions just described cmd x18G ibcmd gpib0 cmd 4 ibrd gpib0 status 1 cmd x19_ ibcmd gpib0 cmd 2 The first ibcmd function is used to send the string of ASCII commands assigned in the first program line These are Unlisten listen address of the board with primary address 1 Serial Poll Enable x18 hex 18 and talk a
144. g used to describe the method of signaling the end of the data to the Listener It should be set to one of the following constants NLend Send NL linefeed with EOI after the data bytes DABend Send EOI with the last data byte in the string NULLend Do nothing to mark the end of the transfer These constants are defined in the header file ugpib h Example Send an identification query to the GPIB device at address 8 Terminate the transmission using a linefeed character with END Send 0 8 IDN 5 NLend NI 488 2M Reference Manual 4 24 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines SendCmds 3 SendCmds 3 Purpose Send GPIB command bytes Syntax void SendCmds int board char commands unsigned long count board specifies a board number commands contains command bytes to be sent onto the GPIB The number of bytes to be sent from the string is indicated by the argument count The count value is of type long However integer values and variables may also be passed SendCmds is not normally required for GPIB operation It is to be used when specialized command sequences which are not provided for in other routines must be sent onto the GPIB Example Controller at address 0 simultaneously triggers GPIB devices at addresses 8 and 9 and immediately places them into local mode Sendcmds 0 x3F x40 x28 x29 x04 x01 6 National Instruments Corp 4
145. gramming The term command as used here should not be confused with some device instructions which can also be called commands Such device specific instructions are actually data messages Talkers Listeners and Controllers A Talker sends data messages to one or more Listeners The Controller manages the flow of information on the GPIB by sending commands to all devices Devices can be Listeners Talkers and or Controllers A digital voltmeter for example is a Talker and may be a Listener as well The GPIB is a bus like an ordinary computer bus except that the computer has its circuit cards interconnected via a backplane bus whereas the GPIB has standalone devices interconnected via a cable bus National Instruments Corp D 1 NI 488 2M Reference Manual Operation of the GPIB Appendix D The role of the GPIB Controller can also be compared to the role of the CPU of a computer but a better analogy is to the switching center of a city telephone system The switching center Controller monitors the communications network GPIB When the center Controller notices that a party device wants to make a call send a data message it connects the caller Talker to the receiver Listener The Controller addresses a Talker and a Listener before the Talker can send its message to the Listener After the message is transmitted the Controller may unaddress both devices Some bus configurations do not require a Controller For
146. he GPIB controller board to go to standby and therefore allow transfers between GPIB devices to occur without its intervention If the shadow handshake option is activated the GPIB board participates in data handshake as an Acceptor without actually reading the data It monitors the transfers for the END message and holds off subsequent transfers Through this mechanism the GPIB board can take control synchronously on a subsequent operation such as ibcmd or ibrpp Before performing an ibgts with shadow handshake the ibeos function should be called to establish the proper EOS character or to disable EOS detection The ECIC error results if the GPIB board is not CIC Refer also to IBCAC In the examples that follow GPIB commands and addresses are coded as printable ASCII characters Board Function Examples Turn the ATN line off after unaddressing all Listeners UNL or ASCII addressing a Talker at hex 46 ASCII F and addressing a Listener at hex 31 ASCII 1 so that the Talker can send data messages ibcmd brd0 F1 3 ibgts brd0 1 NI 488 2M Reference Manual 5 46 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBIST 3 IBIST 3 Purpose Set or clear individual status bit for Parallel Polls Syntax intibist intud int v ud specifies an interface board If v is non zero the individual status bit is set If v is zero the bit is cleared The ibist function is used
147. he Interface Bus Interactive Control ibic program you can communicate with the GPIB devices through functions you enter at the keyboard This feature helps you learn how to communicate with the device troubleshoot problems and develop your application ibic functions include most of the NI 488 functions and NI 488 2 routines described in Chapter 4 NI 488 2M Software Characteristics and Routines and Chapter 5 NI 488M Software Characteristics and Functions respectively plus auxiliary functions used only by ibic In ibic the user can send data and GPIB commands to a device from the keyboard and display data received from a device on the screen After each command executes the numeric value and mnemonic representation of the status word ibsta is displayed The byte count ibcnt and error code iberr are also shown when appropriate This interactive method of data input and data status output is designed to help you learn how to use the NI 488 functions and NI 488 2 routines to program your device Once you develop a sequence of steps that works successfully for your system you can easily incorporate the sequence into an application program using the appropriate language and syntax described in Chapter 3 Understanding the NI 488 2M Software Chapter 4 488 2M Software Characteristics and Routines and Chapter 5 NI 4858M Software Characteristics and Routines Running ibic The ibic program ibic is an executable file that was copie
148. he UNIX signal number that the driver sends to the user process when the condition specified in ibsgn1l occurs IbaHSCableLength 0 001 0 High speed handshaking is disabled 1 to 15 The number of meters of GPIB cable in your system The NI 488 2M software uses this information to select the appropriate timing in the high speed handshaking mode IbaBaseAddr 0x0201 The base I O address of the board IbaDmaChannel 0x0202 The DMA channel that the board is configured to use IbalrqLevel 0x0203 The interrupt level that the board is configured to use National Instruments Corp 5 17 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBASK 3 continued IBASK 3 Table 5 3 lists the options you can use with ibask when ud is a device descriptor or a device index The following is an alphabetical list of the option constants included in Table 5 3 Constants Values Constants Values IbaBNA 0x0200 baReadAdjust 0x0013 e baEndBitlisNormal 0x001A e IbaREADDR 0x0006 baEOSchar Ox000F e IbaSAD 0x0002 e IbaEOScmp O0x000E e baSPollTime 0x0018 IbaEOSrd 0x000C e IbaTMO 0x0003 IbaEOSwrt 0x000D baUnAddr 0x001B baEOT 0x0004 baWriteAdjust 0x0014 baPAD 0x0001 Table 5 3 ibask Device Configuration Parameter Options Options Options Constants Values Returned Information IbaPAD 0x0001 The current primary address of the device See ibpad IbaSAD 0x0002 T
149. he current secondary address of the device See ibsad IbaTMO 0x0003 The current I O timeout of the device See ibtmo IbaEOT 0x0004 zero The GPIB EOI line is not asserted at the end of a write operation non zero EOI is asserted at the end of a write operation See ibeot continues NI 488 2M Reference Manual 5 18 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBASK 3 continued IBASK 3 Table 5 3 ibask Device Configuration Parameter Options Continued Options Options Constants Values Returned Information IbaREADDR 0 0006 zero No unnecessary addressing is performed between device level read and write operations non zero Addressing is always performed before a device level read or write IbaEOSrd Ox000C zero The EOS character is ignored during read operations non zero Read operation is terminated by the EOS character See ibeos IbaEOS wrt 0x000D zero The EOI line is not asserted when the EOS character is sent during a write operation non zero The EOI line is asserted when the EOS character is sent during a write operation See ibeos IbaEOScmp OxO00E zero A 7 bit compare is used for all EOS comparisons non zero An 8 bit compare is used for all EOS comparisons See ibeos IbaEOSchar 0x000F The current EOS character of the device See ibeos continues National Instruments Corp 5 19 NI 488 2M Ref
150. her Controller LACS is also set whenever the GPIB board shadow handshakes as a result of the ibgts function LACS is cleared whenever the GPIB board detects the Unlisten UNL command its own talk address Interface Clear IFC or ibgts is called without shadow handshake DTAS brd DTAS indicates whether the GPIB board has detected a device trigger command DTAS is set whenever the GPIB board as a Listener detects the Group Execute Trigger GET command has been sent by another Controller DTAS is cleared in the status word on any call immediately following an ibwait call if the DTAS bit is set in the ibwait mask parameter DCAS brd DCAS indicates whether the GPIB board has detected a device clear command DCAS is set whenever the GPIB board detects the Device Clear DCL command has been sent by another Controller or whenever the GPIB board as a Listener detects the Selected Device Clear SDC command has been sent by another Controller DCAS is cleared in the status word on any call immediately following an ibwait call if the DCAS bit was set in the ibwait mask parameter or on any call immediately following a read or write In addition to the previous conditions the following situations also affect the status word bits NI 488 2M Reference Manual 3 10 National Instruments Corp Chapter 3 Understanding the NI 488 2M Software e Acallto the function ibonl clears the following bits END LOK REM CIC TACS LACS DTAS DCAS e
151. ibclr vmtr clear it National Instruments Corp 5 23 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBCMD 3 IBCMD 3 Purpose Send GPIB command messages Syntax int ibcmd intud char cmd long cnt ud specifies an interface board cmd contains the commands to be sent over the GPIB The ibcmd function is used to transmit interface messages commands over the GPIB These commands are listed in Appendix A The ibcmd function is also used to pass GPIB control to another device This function is not used to transmit programming instructions to devices These instructions are transmitted with the ibrd and ibwrt functions The ibcmd operation terminates on any of the following events e commands are successfully transferred e Anerror is detected e time limit is exceeded e Take Control TCT command is sent e An Interface Clear IFC message is received from the System Controller The transfer count may be less than the requested count on any of the previous terminating events but the first The requested transfer count cnt can be any value that fits into a long integer although command transfers are typically very small To more easily accommodate a small count from an application program the C language interface allows an integer value to be passed to the function in place of a long value without any problem An ECIC error results if the GPIB board
152. ibic Supports 6 16 Repeating a Previous Function esses 6 18 National Instruments Corp xi NI 488 2M Reference Manual About This Manual This manual describes the NI 488 2M software including all NI 488 2 routines and NI 488 functions for C Organization of This Manual This manual is organized as follows Chapter 1 Introduction introduces you to the product and the manual Chapter 2 Installation and Configuration of NI 488 2M Software contains the instructions for installing and configuring the NI 488 2M software Chapter 3 Understanding the NI 488 2M Software introduces you to the NI 488 2 routines and NI 488 functions It also contains information for programming the NI 488 2 driver Chapter 4 NI 488 2M Software Characteristics and Routines contains a discussion of the important characteristics of the NI 488 2 routines This chapter also contains specific information for programming the NI 488 2 routines in C The descriptions are listed alphabetically for easy reference Chapter 5 NI 488M Software Characteristics and Functions contains information for programming the NI 488 functions This chapter also contains specific information for programming the NI 488 2 functions in C The descriptions are listed alphabetically for easy reference Chapter 6 ibic introduces you to the Interface Bus Interactive Control ibic program This chapter also tells you how to
153. ibsta is set iberr is the first error detected Device IBRDF Function If ud specifies a device the same board functions as the device ibrd function are performed automatically The ibrdf function terminates on similar conditions as ibrd NI 488 2M Reference Manual 5 64 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBRDF 3 continued IBRDF 3 Board IBRDF Function If ud specifies an interface board the board ibrd function reads from a GPIB device that is assumed to be already properly addressed An EADR error results if the board is CIC but has not been addressed to listen with the ibcmd function An EABO error results if for any reason the read operation does not complete within the time limit An EABO error also results if the device that is to talk is not addressed and or the operation does not complete within the time limit for whatever reason Device Function Example Read data from the device rdr into the file rdgs ibrdf rdr rdgs Board Function Examples Read data from a device at talk address amp H4C ASCII L to the file rags on the current disk drive and then unaddress everyone the GPIB board listen address is hex 20 or ASCII lt space gt ibcmd brdO L 3 ibrdf brd0 rdgs National Instruments Corp 5 65 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBRPP 3 IBRPP 3 Purpose Conducta Paral
154. ice connected to the indicated board asserts the Service Request SRQ line If the SRQ occurs within the timeout period the variable result will be set to the value 1 If no SRQ is detected before the timeout period expires result will be set to 0 Notice that this call is similar in format to the Test SRQ routine except that Test SRQ returns immediately with SRQ status whereas Wait SRO suspends the program for at most the duration of the timeout period waiting for an SRQ to occur Example Wait for a GPIB device to request service and then determine which of three devices at addresses 8 9 and 10 requested the service Addr4882_t addresslist 4 8 9 10 NOADDR short resultlist 3 short result WaitSRO 0 amp result if result 1 FindRQS 0 addresslist resultlist NI 488 2M Reference Manual 4 36 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines C GPIB Programming Example You can take full advantage of the IEEE 488 2 1992 standard by using the NI 488 2 routines These routines are completely compatible with the controller commands and protocols defined in IEEE 488 2 The NI 488 2 routines are easy to learn and use Only a few routines are needed for most application programs This example illustrates the programming steps that could be used to program a representative IEEE 488 2 instrument from your personal computer using the NI 488 2 routines The application is wri
155. ices use a value of v equal to 2 to leave IFC asserted and a value of v equal to 0 to unassert IFC Any value for v other than 0 or 2 will pulse IFC Note The v parameter is not supported in newer versions of the NI 488 2M driver To determine if your version supports the v parameter refer to the C language interface cib c or to the function prototypes contained in the include file ugpib h The IFC signal resets only the GPIB interface functions of bus devices and not the internal device functions Device functions are reset with the Device Clear DCL and Selected Device Clear SDC commands To determine the effect of these messages consult the device documentation The ESAC error occurs if the GPIB board does not have System Controller capability Refer also to IBRSC Board Function Example At the beginning of a program initialize the GPIB and become CIC and Active Controller ibsic brd0 1 National Instruments Corp 5 77 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBSRE 3 IBSRE 3 Purpose Set or clear the Remote Enable line Syntax int ibsre intud int v ud specifies an interface board If v is non zero the Remote Enable REN signal is asserted If v is zero the signal is unasserted The ibsre function turns the REN signal on and off REN is used by devices to select between local and remote modes of operation A device does not actually enter remote mode
156. ics and Functions IBDEV 3 continued IBDEV 3 Device Function Example ibdev opens an available device and assigns it to access gpib 0 board 0 with a primary address of 6 pad 6 a secondary address of 0x67 sad 0x67 a timeout of 10 ms tmo 7 the END message enabled eot 1 and the EOS mode disabled eos 0 if ud ibdev 0 6 0x67 7 1 0 lt 0 Handle GPIB error here if iberr EDVR bad boardindex or no devices available x7 else if iberr EARG The call succeeded but at least one of pad sad tmo eos eot is incorrect National Instruments Corp 5 37 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBDMA 3 IBDMA 3 Purpose Enable or disable DMA Syntax int ibdma intud int v ud specifies an interface board If v is non zero DMA transfers between the GPIB board and memory are used for read and write operations If v is zero programmed T O is used Some GPIB boards support more than one type of DMA transfer For these boards v selects the DMA type Consult the Getting Started manual that you received for more information The assignment made by this function remains in effect until ibdma is called again ibonl or ibfind function is called or the system is restarted When is called and an error does not occur the previous value of v is stored in iberr Board Function Exa
157. ided with the hardware items National Instruments Corp 1 1 NI 488 2M Reference Manual Chapter 2 Installation and Configuration of NI 488 2M Software This chapter contains instructions for installing and configuring the NI 488 2M software Software Installation For a list of files that will be copied from the distribution diskette and for information on installing the software refer to the getting started manual or installation guide that you received with your interface board Software Configuration Before you can run the software diagnostic tests the NI 488 2M software driver must be loaded If you have just completed the installation procedure and have not restarted your computer the driver is not yet loaded You must run the software configuration utility ibconf you must have super user privilege because it creates all special files or device nodes needed by the software You also use ibconf to inspect and modify the default software parameters Refer to the ibconf section for information on ibconf and on the configurable software options and their default values Board Reference Numbers The NI 488 2M driver supports up to four interface boards These boards are referenced by number from your application program The reference number is zero 0 for the first board and one 1 for the second board If you installed two boards in your computer and you do not know which board is 0 and which board is 1 run
158. iguration settings of the interface board ibonl brd0 1 NI 488 2M Reference Manual 5 56 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBPAD 3 IBPAD 3 Purpose Change Primary Address Syntax int ibpad intud int v ud specifies a device or an interface board v specifies the primary GPIB address ibpad is needed only to alter the configuration setting There are 31 valid GPIB addresses ranging from 0 to hex 1E that is the lower five bits of v are significant and they must not all be ones An EARG error results if the value of v is not in this range The assignment made by this function remains in effect until ibpad is called again the ibonl or ibfind function is called or the system is restarted When ibpad is called and an error does not occur the previous primary address is stored in iberr Device IBPAD Function If ud specifies a device ibpad determines the talk and listen addresses based on the value of v A device listen address is formed by adding hex 20 to the primary address the talk address is formed by adding hex 40 to the primary address A primary address of hex 10 corresponds to a listen address of hex 30 and a talk address of hex 50 The actual GPIB address of any device is set within that device either with hardware switches or a software program Refer to the device documentation for instructions Board IBPAD Function If ud specifies a boar
159. ine the RQS bit in the status word and call the ibrsp function to examine the status byte whenever it appears It is possible for a serial poll response queue of a device to get clogged with old status bytes when you neglect to call ibrsp to empty the queue Error condition ESTB is returned only by ibrsp when it becomes necessary to report that status bytes have been discarded due to a full queue If your application has no interest in SRQ or status bytes you can ignore the occurrence of the automatic polls Note If the RQS bit of the device status word is still set after ibrsp is called the response byte queue has at least one more response byte remaining ibrsp should be called until RQS is cleared to gather all stored response bytes and to guard against queue overflow National Instruments Corp 5 3 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 Compatibility Autopolling is incompatible with the signal interrupt feature That is either the user or the driver can be in charge of handling SRQ but not both You should disable Autopolling if you intend to make use of signal interrupt Refer to Chapter 3 Understanding the NI 488 2M Software for a description of the NI 488 2M driver s signal interrupt feature Detection of the SRQI bit in device status words ibsta 15 not possible if Autopolling is enabled This is because the goal of Autopolling is to make SRQ on the IEEE 488 bus go away thus
160. ing Send The Send routine sends data to a single GPIB device The SendList command can be used to send data to multiple GPIB devices For example to send the five character string IDN followed by the NL character with EOI from the computer to the devices at primary address 2 and 17 enter the following command at the 488 2 0 prompt 488 2 0 SendList 2 17 IDN NLend 0128 cmpl cic atn tacs count 5 The returned status word 0128 indicates a successful I O completion while the byte count indicates that all five characters were sent from the computer and received by both devices Using Receive The Receive routine causes the GPIB board to receive data from another GPIB device The following example illustrates the use of the Receive routine 488 2 0 Receive 5 10 STOPend 2124 end 1 cic tacs count 5 48 65 6c 6f Hello The command acquires data from the device at primary address 5 It stops receiving data when ten 10 characters have been received or when the END message is received The acquired data is then displayed in hex format along with its ASCII equivalent The status word and byte count are also displayed Using NI 488 Functions In using ibic the most important NI 488 functions are the HELP ibfind or ibdev ibwrt and ibrd commands These functions are described in the following paragraphs National Instruments Corp 6 3 NI 488 2M Reference Manual ibic Chapter 6 Using HELP
161. integer Hex numbers must be preceded by zero and x for example OxD Octal numbers must be preceded by zero only for example 015 Other numbers are assumed to be decimal 4 string consists of a list of ASCII characters octal or hex bytes or special symbols The entire sequence of characters must be enclosed in quotation marks octal byte consists of a backslash character followed by the octal value For example octal 40 would be represented by N40 A hex byte consists of a backslash character and a character x followed by the hex value For example hex 40 would be represented by x40 The two special symbols are r for a carriage return character and n for a linefeed character These symbols provide a more convenient method for inserting the carriage return and linefeed characters into the string as shown in the following string F3R5T1 r n Because the carriage return can be represented equally well in hex xD and are equivalent strings 5 udname is the symbolic name of the new device or board for example ibfind dev1 or set gpibO 6 visthe number of bytes to read 7 flname is the pathname of the file to be read or written for example meter or printrbuf 8 mask isa hex octal or decimal integer see note 3 or a mask bit mnemonic 9 ibdev parameters are board id pad sad tmo eos and eot 10 ibln parameters pad and sad National Instruments Corp 6 13 NI 488 2M Reference Manual
162. ion of NI 488 2M Software Chapter 2 NI 488 Functions and NI 488 2 Routines The NI 488 2M driver is a subroutine structured device driver The NI 488 2M driver is faster than other available device drivers easily handles buffered DMA transfers and uses a structured hierarchical programming style familiar to users of modern programming languages The NI 488 functions and NI 488 2 routines are described in Chapter 3 Understanding the NI 488 2M Software Chapter 4 NI 488 2M Software Characteristics and Routines and Chapter 5 NI 488M Software Characteristics and Functions of this manual An NI 488 2 or NI 488 language interface is required to link application programs to the driver The following is a C example of a high level NI 488 function that writes an array of bytes to a device data RST OHMS VAL1 ibwrt scope data 18 Interactive Control Program ibic A good way to begin learning your GPIB system is to use the Interface Bus Interactive Control ibic program described in Chapter 6 ibic With ibic you can program your instruments interactively from the keyboard rather than from an application program Using ibic helps you quickly understand how the instruments and the NI 488 2M driver work It also immediately returns the same status information that is returned as global variables in an application program While running ibic study the descriptions of each function given in Chapter 6 ibic to fully understand th
163. ional Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions Write the function range and trigger source instructions to Fluke 45 ibwrt bd RST VAC AUTO TRIGGER 2 SRE 16 351 if ibsta amp ERR gpiberr ibwrt Error exit 1 Send the GET message to trigger a measurement reading ibcmd 010 11 if ibsta amp ERR gpiberr ibcmd Error exit 1 Request the triggered measurement reading ibwrt bd VAL1 51 if ibsta amp ERR gpiberr ibwrt Error exit 1 Wait for the DVM to set SRQ or for a timeout if the current time limit is too short use ibtmo to change it printf Waiting for SRQ n printr ot mto if ibwait bd TIMO SRQI amp ERR TIMO gpiberr ibwait Error exit 1 Because neither a timeout nor an error occurred ibwait must have returned on SRQ Next do a serial poll First unaddress bus devices and send the Serial Poll Enable SPE command followed the talk address of the Fluke 45 and the listen address of the GPIB board ibcmd bd _ 030A 5L UNL UNT SPE TAD MLA if ibsta amp ERR gpiberr ibcmd Error exit 1 Now read the status byte If it is 0x50 the Fluke 45 has valid data to send otherwise it has a fault condition to report National Instruments Corp 5 97 NI 488 2M Reference Manual NI 488M Software Charact
164. ional Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBEOS 3 continued IBEOS 3 2 program the interface board brdo to terminate read operations on the 8 bit value hex 82 rather than the 7 bit character hex change lines 10 and 100 in Example 1 v BIN REOS 0x82 ibeos brd0 v 3 disable read termination on receiving the EOS character change line 100 in Example 1 v n ibeos brd0 v 4 Send END when the linefeed character is written v XEOS n ibeos brd0 v ibwrt brd0 123 n 4 5 send END with linefeeds and to terminate reads on linefeeds change line 100 in Example 4 REOS XEOS O0x0A ibeos brd0 v National Instruments Corp 5 41 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBEOT 3 IBEOT 3 Purpose Enable disable END message on write operations Syntax intibeot intud int v ud specifies a device or an interface board If v is non zero the END message is sent automatically with the last byte of each write operation If v is zero END is not automatically sent ibeot is needed only to alter the value from the configuration setting In the default configuration this feature is enabled The END message is the assertion of the GPIB EOI signal If the automatic END termination message is enabled it is not necessary to use the EOS character to
165. ional Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBLOC 3 IBLOC 3 Purpose Go to local Syntax int ibloc int ud ud specifies a device or an interface board Unless the Remote Enable line has been unasserted with the ibsre function all device functions automatically place the specified device in remote program mode ibloc is used to move devices temporarily from a remote program mode to a local mode until the next device function is executed on that device Device IBLOC Function ibloc places the device indicated in local mode by calling ibcmd to send the following command sequence 1 Talk address of the access board 2 Secondary address of the access board if necessary 3 Unlisten UNL 4 Listen address of the device 5 Secondary address of the device if necessary 6 Go To Local GTL Other command bytes may be sent as necessary Board IBLOC Function If ud specifies an interface board the board is placed in a local state by sending the local Return To Local RTL message if it is not locked in remote mode The LOK bit of the status word indicates whether the board is in a lockout state The ibloc function is used to simulate a front panel RTL switch if the computer is used as an instrument National Instruments Corp 5 53 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBLOC 3 continued IBLOC 3 Device Function Example
166. ions found in the IEEE 488 2 specification document and that strictly adheres to the command and data sequences found there Using National Instruments NI 488 2 routines together with compliant 488 2 compatible devices can result in greater predictability of instrument behavior and programming correctness and increased similarity in the ways that instruments of different manufacturers are programmed General Programming Information The NI 488 2 routines use the Controller protocols and procedures described in the IEEE 488 2 specification The calling syntax of the routines is intended to closely resemble the implementations suggested in that specification document National Instruments Corp 4 1 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 The NI 488 2 set of routines consists of the following routines whose functionality can be broken down into the following groups e Simple Device I O Send Receive e Multiple Device I O SendList e Simple Device Control Trigger DevClear ReadStatusByte PPoll PPollConfig PPollUnconfig PassControl e Multiple Device Control TriggerList DevClearList EnableRemot EnableLocal FindRQS AllSpoll e Bus Management ResetSys SendIFC FindLstn TestSRQ WaitSRQ TestSys SendLLO SetRWLS Low level I O SendCmds SendDataBytes NI 488 2M Reference
167. lel Poll Syntax int ibrpp intud char ppr ud specifies a device or an interface board ppr stores the parallel poll response Device IBRPP Function If ud specifies a device all devices on its GPIB are polled in parallel using the access board of that device This is done by executing the board ibrpp function with the appropriate access board specified Board IBRPP Function If ud specifies a board the ibrpp function causes the identified board to conduct a parallel poll of previously configured devices by sending the IDY message ATN and EOI both asserted and reading the response from the GPIB data lines An ECIC error results if the GPIB board is not CIC If the GPIB board is Standby Controller it takes control and asserts ATN becomes Active prior to polling It remains Active Controller afterward In the examples that follow some of the GPIB commands and addresses are coded as printable ASCII characters The simplest means of specifying values is to use printable ASCII characters to represent values When possible ASCII characters should be used This is the simplest means of specifying the values Refer to Appendix A for conversions of numeric values to ASCII characters NI 488 2M Reference Manual 5 66 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBRPP 3 continued IBRPP 3 Some commands relevant to parallel polls are shown in Table 5 7 Table 5 7 Parallel Poll C
168. length of time that many functions wait for an I O operation to finish These functions include most functions that access the GPIB bus Some of these functions are as follows e ibcmd ibrd ibwrt The ibtmo function also changes the length of time that device functions wait for commands to be accepted If a device does not accept commands within the time limit the EBUS error will be returned When ibtmo is called and an error does not occur the previous timeout code value is stored in iberr Device IBTMO Function If ud specifies a device the new time limit is used in subsequent device functions directed to that device Board IBTMO Function If ud specifies a board the new time limit is used in subsequent board functions directed to that board Refer also to BWAIT and Table 2 1 NI 488 2M Reference Manual 5 80 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBTMO 3 continued IBTMO 3 Device Function Example Change the time limit for calls involving the device tape to approximately 300 ms tape ibfind dev9 ibtmo tape 10 Board Function Examples Change the time limit to 10 ms for board functions using brdo ibtmo brd0 7 National Instruments Corp 5 81 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBTRG 3 IBTRG 3 Purpose Trigger selected device Syntax int ibtrg int ud ud specifies
169. ller Board Characteristic Only 2 12 Disable Auto Serial Polling Board Characteristic Only 2 12 GPIB Bus Timing Board Characteristic Only 2 12 UNIX Signal Board Characteristic Only 2 13 DMA Mode Board Characteristic Only 2 13 ibconf teet pere 2 13 Using Your NI 488 2M Software seen 2 13 NI 488 Functions and NI 488 2 Routines 2 14 Interactive Control Program ibic 2 14 The Application Program esee 2 14 Chapter 3 Understanding the NI 488 2M 3 1 Introduction to the NI 488 2 Routines eese 3 1 Introduction to the NI 488 Functions eene 3 2 Device Functions leere Eee metere mes 3 2 Board F nctionS sa eei cete tte e Ee dees e rie ERE ERR 3 3 More About Device and Board Functions 3 3 Opening Boards and Devices sese 3 4 IBFIND board or devname 3 4 Programming Features Common to NI 488 2 Routines and NI 438 Punctlons uet nte deter p RR Rer 3 4 Multiboard Handler 3 5 Learning NI 488 2 and Your Instruments 3 6 General Programming Information eee 3 6 Status Word 1Ds
170. luke RST 4L NLend NI 488 2M Reference Manual 4 40 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines if ibsta amp ERR gpiberr Send RST Error exit 1 Set up for a test Allow the Fluke to assert SRQ when it has a message to send xy Send 0 fluke VAC AUTO TRIGGER 2 SRE 16 291 NLend if ibsta amp ERR gpiberr Send Setup Error exit 1 for m 0 m lt 10 m Trigger the Fluke x Send 0 fluke TRG VAL1 111 NLend if ibsta amp ERR gpiberr Send Trigger Error exit 1 Wait for the Fluke to assert SRQ meaning it is ready with the measurement WaitSRQ 0 amp SRQasserted if SRQasserted printf SRQ is not asserted The Fluke is not printf ready n exit 1 Read its status byte Be sure that the MAV Message Available bit is set ReadStatusByte 0 fluke amp statusByte if ibsta amp ERR gpiberr ReadStatusByte Error exit 1 if statusByte amp MAVbit gpiberr Improper Status Byte printf Status Byte 0x x n statusByte exit 1 National Instruments Corp 4 41 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 Read the measurement Receive 0 fluke buffer 10L STOPend if ibsta amp ERR gpiberr Receive Error exit 1 buffer ibcnt 0 printf Reading s n buffer
171. m Controller of its IEEE 488 bus which is the usual configuration As long as the GPIB interface board is the System Controller it can become the Controller In Charge CIC If the GPIB board is not CIC or is unable to become CIC it will not be able to execute device functions and any call to a device function that uses the IEEE 488 bus will return an ECIC error The driver waits using the current timeout value of the board for control to be passed to the GPIB interface board If the board fails to become CIC before the timeout period elapses an ECIC error is returned This error might occur for example if the GPIB interface board is assumed to be the System Controller but was not configured as such during software installation Automatic Serial Polling Automatic Serial Polling is a feature of the driver that is intended to relieve you from the burden of sorting out occurrences of SRQ and status bytes of a device Automatic Serial Polling or Autopolling can be enabled by using the configuration utility ibconf If Autopolling is enabled the driver automatically conducts serial polls when SRQ is asserted NI 488 2M Reference Manual 5 2 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions As part of the Autopoll procedure the driver stores each positive serial poll response that is those responses that have the RQS or hex 40 bit set in the device status byte in a queue associated with each devi
172. ments Corp B 7 NI 488 2M Reference Manual Appendix Redirection to the GPIB Access to GPIB devices is controlled by the driver which uses internal tables of device specific information Standard drivers support up to two boards and 16 devices A device can be assigned any board to use as its access board The utility ibconf is used to edit the internal board and device tables The device tables contain information such as GPIB primary and secondary addresses end of string modes and timeout limits Once this information is properly set up it is possible to communicate with GPIB devices without any knowledge of GPIB protocol Shell commands such as the following will work as expected cat file dev gpibplotter National Instruments Corp C1 NI 488 2M Reference Manual Appendix Operation of the GPIB Communication among interconnected GPIB devices is achieved by passing messages through the interface system Types of Messages The GPIB carries device dependent messages and interface messages e Device dependent messages often called data or data messages contain device specific information such as programming instructions measurement results machine status and data files Interface messages manage the bus itself They are usually called commands or command messages Interface messages perform such tasks as initializing the bus addressing and unaddressing devices and setting device modes for remote or local pro
173. mples 1 Enable DMA transfers using the previously configured channel ibdma brd0 1 Any non zero value will do 2 Disable DMA and use programmed I O exclusively ibdma 0 NI 488 2M Reference Manual 5 38 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBEOS 3 IBEOS 3 Purpose Change or disable End Of String termination mode Syntax int ibeos intud int v ud specifies a device or an interface board v specifies the EOS character and the data transfer termination method according to Table 5 6 ibeos is needed only to alter the value from its configuration setting The assignment made by this function remains in effect until ibeos is called again the ibonl or ibfind function is called or the system is restarted When ibeos is called and an error does not occur the previous value of v is stored in iberr Table 5 6 Data Transfer Termination Method Value of v Method High Byte Low Byte A Terminate read when EOS is 00000100 EOS detected B Set EOI with EOS on write function 00001000 C Compare all 8 bits of EOS byte rather than low 7 bits all read and write functions 00010000 EOS Methods A and C determine how read operations terminate If Method A alone is chosen reads terminate when the low seven bits of the byte that is read match the low seven bits of the EOS character If Methods A and C are chosen a full 8 bit comparison is used Me
174. n 4 6 4 13 FindRQS 4 6 4 14 ibic 6 20 to 6 22 PassControl 4 6 4 15 PPoll 4 6 4 16 PPollConfig 4 6 4 17 PPollUnconfig 4 6 4 18 RcvRespMsg 4 6 4 19 ReadStatusByte 4 6 4 20 National Instruments Corp Index 11 488 2 Reference Manual Index Receive 4 6 4 21 ReceiveSetup 4 6 4 22 ResetSys 4 6 4 23 Send 4 6 4 24 SendCmds 4 6 4 25 SendDataBytes 4 6 4 26 SendIFC 4 7 4 27 SendList 4 7 4 28 SendLLO 4 7 4 29 SendSetup 4 7 4 30 SetRWLS 4 7 4 31 TestSRQ 4 7 4 32 TestSys 4 7 4 33 Trigger 4 7 4 34 trigger devices 4 7 TriggerList 4 7 4 35 WaitSRQ 4 5 4 7 4 36 NI 488 board functions compatibility with NI 488 2 routines 4 4 NI 488 calls 4 4 NI 488 functions 3 2 to 3 6 5 1 to 5 99 ibask 5 5 5 11 to 5 20 ibbna 5 5 5 21 ibcac 5 5 5 22 ibclr 5 5 5 23 ibemd 5 5 5 24 to 5 25 ibconfig 5 5 5 26 to 5 35 ibdev 5 5 5 36 to 5 37 ibdma 5 5 5 38 ibeos 5 5 5 39 to 5 41 ibeot 5 6 5 42 to 5 43 ibfind 5 4 5 5 5 44 to 5 45 ibgts 5 6 5 46 ibist 5 6 5 47 iblines 5 6 5 48 to 5 49 ibllo 5 50 ibln 5 6 5 51 to 5 52 ibloc 5 6 5 53 to 5 54 ibonl 5 6 5 55 to 5 56 ibpad 5 6 5 57 to 5 58 ibpct 5 6 5 59 ibppc 5 6 5 60 to 5 61 ibrd 5 5 5 6 5 62 to 5 63 NI 488 2M Reference Manual Index 12 National Instruments Corp Index ibrdf 5 6 5 64 to 5 65 ibrpp 5 6 5 66 to 5 68 ibrsc 5 6 5 69 ibrsp 5 3 5 6 5 70 to 5 71 ibrsv 5 6 5 72 ibsad
175. nclude the following e Communicating with non compliant non IEEE 488 2 devices e Altering various low level board configurations e Managing the bus in non typical ways The original National Instruments NI 488 board functions are compatible with and can be interspersed within sequences of NI 488 2 routines For example a call to ibtmo can be issued within sequences of NI 488 2 routines to alter the timeout value call to iblines can be issued to monitor the state of any given GPIB line and so on To make these calls from within a sequence of NI 488 2 routines the usual call to ibfind is not required merely substitute the board number as the first parameter of the NI 488 board function Thus all calls in the sequence both NI 488 2 and NI 488 will have the same board number usually 0 as the first parameter Using these calls as needed within an NI 488 2 program ensures that non standard or unusual situations or devices can be dealt with easily NI 488 2M Reference Manual 4 4 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines Timeouts Most of the NI 488 2 routines particularly those involving the transfer of command sequences or data messages are regulated by the same timeout mechanism that regulates the NI 488 calls A default timeout period of 10 seconds is preconfigured in the driver thus all I O must complete within that period to avoid a timeout error In addition the WaitSRQ routi
176. ne waits for this period before returning with a no SRQ indication The default timeout value can be changed with the ibconf utility In addition you can use the NI 488 board function call ibtmo to programmatically alter the timeout period Refer to the description of the ibtmo function in Chapter 5 NI 488M Software Characteristics and Functions for more information Regardless of the I O and Wait timeout period a much shorter timeout is enforced for responses to serial polls This shorter timeout period takes effect whenever a serial poll is conducted Because devices normally respond quickly to polls there is no need to wait for the relatively lengthy I O timeout period for a non responsive device C NI 488 2 Routines Table 4 1 lists the call syntax for each NI 488 2 routine and a brief description of these routines for C Table 4 1 C NI 488 2 Routines AllSpoll board addresslist Serial poll all devices resultlist DevClear board address Clear a single device DevClearList board addresslist Clear multiple devices EnableLocal board addresslist Enable operations from the front of a device EnableRemote board addresslist Enable remote GPIB programming of devices continues National Instruments Corp 4 5 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 Table 4 1 C NI 488 2 Routines Continued FindLstn board addresslist resultlist limit FindRQS board ad
177. ng options are available at the upper level e Device Maps of the Boards e Help e Rename e Dis connect e Edit e National Instruments Corp 2 3 NI 488 2M Reference Manual Installation and Configuration of NI 488 2M Software Chapter 2 Device Maps of the Boards Press lt Control B gt or lt Control F gt to toggle between the device maps for the different GPIB interface boards These boards are referred to as access boards The maps show which devices are assigned to each board By default some devices are attached to the access board named gpib0O and other devices are not attached to any board Help Press lt Control Q gt to access the comprehensive online help feature of ibconf The help information describes the functions and common terms associated with the upper level of ibconf Rename Press lt Control R gt to rename a device Uppercase and lowercase letters are not treated the same Device names can be up to 14 characters long but only the first seven characters will show up in the device map Note You must not give GPIB device names the same names as files directories and or subdirectories If you name a GPIB device pltr and your file system contains the file o1t x ora subdirectory pltr a conflict results Please note that the access board names such as gpib0 cannot altered The string representing a device or access board name is the first variable argument of the function ibfin
178. ns Appendix B ESTB 15 Error Condition Serial poll status byte s lost Solutions e Call ibrsp more often to read the status bytes e Ignore ESTB ESRQ 16 Error Condition SRQ stuck in the ON position Solutions e Ignore ESRQ until all devices are found ESRQ occurred because the device asserting SRQ was not opened with ibfind The automatic serial polling function polls only the opened devices e Check that you have used ibfind to open all devices on the GPIB that could assert SRQ Remove any device from the bus that is not being accessed e Using ibic attach one device at a time and determine that it is unasserting SRQ after being polled e Inspect the interconnecting cable to see that the devices are attached and that the connectors are seated properly ETAB 20 Error condition Table problem Solutions e FortheFindLstn routine this is a warning and not an error condition You can either ignore this message or increase the size of the buffer NI 488 2M Reference Manual B 6 National Instruments Corp Appendix Common Errors and Their Solutions e For the FindRQS routine this error indicates that none of the specified devices are requesting services Check to be sure that the device list contains the addresses of all on line devices Also FindRQS should normally be called only when the SRQ line is asserted Use the TestSRQ or WaitSRQ routines to determine the state of SRQ National Instru
179. ntifies which of these opened units ibic will use in subsequent calls Use the SET function to change from one of these units to another National Instruments Corp 6 9 NI 488 2M Reference Manual ibic Chapter 6 Tables 6 1 and 6 2 summarize the NI 488 functions and syntax and NI 488 2 routines respectively when called from ibic Syntax rules for ibic are explained in the table notes Consult Chapter 4 M 488 2M Software Characteristics and Routines and Chapter 5 NI 488M Software Characteristics and Functions for detailed descriptions of functions and routines respectively and for syntax rules of the programming language you will use Table 6 1 Syntax of GPIB Functions in ibic Function Function Syntax Description pus ibbna Change access board of device brdname ibdev Open an unused device when the Ma NTC device name is unknown ibdma v Enable disable DMA Change disable EOS message Ibest Enable disable END message ibfind Return unit descriptor dev brd 5 udname ibgts Go from active controller to brd 2 3 standby ibist Read the state of all GPIB lines ba Check for presence of device on bus pue own etw Place device online or offline continues NI 488 2M Reference Manual 6 10 National Instruments Corp Chapter 6 ibic Table 6 1 Syntax of GPIB Functions in ibic Continued E _ e no Syntax Description Type Note _ ray
180. o file Signal Interrupting C programs may be signaled on the occurrence of a GPIB event When the signal occurs the program goes to a user specified signal handler The signal handler is attached using the UNIX signal function The default signal to be raised is SIGINT and may be changed using the ibconf utility A special function ibsgnl is used to make the NI 488 2M driver assert a UNIX signal on the occurrence of a GPIB event The ibsgn1 function is a board level function that is passed a bit mask that specifies which events are to raise the signal A mask bit is set to request a signal when the corresponding event occurs mask of zero disables signals Table 3 3 displays the recognized bits NI 488 2M Reference Manual 3 18 National Instruments Corp Chapter 3 Understanding the NI 488 2M Software Table 3 3 Signal Mask Layout Mnemonic Position Value Description 6 40 GPIB board isin Remote Sate CIC GPIB board is Controller In Charge TACS 3 8 GPIB board is Talker LACS GPIB board is Listener DTAS 1 2 GPIB board is in Device Trigger State DCAS 0 1 GPIB board is in Device Clear State The following is an example program that handles the SIGINT UNIX signal when the SRQI GPIB event occurs void signal_handler signal SIGINT signal handler main int board board ibfind gpib0 Signal SIGINT signal handler ibsgnl board SRQI National Instruments
181. oard SELECT use h or 1 key Primary gpib address lt gt 00H to 1EH Secondary gpib address NONE Timeout setting oe TIOS EOS byte site 00H Terminate read on EOS no Set EOI with EOS on write no Type of compare on EOS 7 bit Set EOI w last byte of write yes Board is system controller Disable auto serial polling High speed timing Use k key to change fields Q help W explain field Y reset value O return to map Figure 2 2 Lower Level of ibconf National Instruments Corp 2 5 NI 488 2M Reference Manual Installation and Configuration of NI 488 2M Software Chapter 2 The lower level screens of ibconf display the currently defined values for characteristics of a device or board such as addressing and timeout information as shown in Figure 2 2 You access these screens from the upper level of ibconf by selecting a board or device and pressing the function key lt Control I gt The configuration settings selected for each device and each board are a means of customizing the communications and other options to be used with that board or device The settings for devices specify the characteristics to be used by the access board for that device when device functions are used The settings for boards or devices specify the characteristics to be used with each board when board fun
182. oard Function Example Find out the current primary address of board brado int pad ibask brd0 IbaPAD amp pad National Instruments Corp 5 11 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions IBASK 3 continued Chapter 5 IBASK 3 Table 5 2 lists the options you can use with ibask when ud is a board descriptor or a board index The following is an alphabetical list of the option constants included in Table 5 2 Constants IbaAUTOPOLL IbaBaseAddr IbaCICPROT IbaDMA IbaDmaChannel IbaEndBitIsNormal IbaEOSchar IbaEOScmp IbaEOSrd IbaEOS wrt IbaEOT IbaHSCableLength IbaIRQ IbalrqLevel Values 0x0007 0x0201 0x0008 0x0012 0x0202 Ox001A Ox000F 0x000E 0x000C 0x000D 0x0004 Ox001F 0x0009 0x0203 NI 488 2M Reference Manual 5 12 Constants IbaPAD IbaPP2 IbaPPC IbaPPollTime IbaReadAdjust IbaSAD IbasC IbaSendLLO IbaSignalNumber IbaSRE IbaTIMING IbaTMO IbaWriteAdjust Values 0x0001 0x0010 0x0005 0x0019 0x0013 0x0002 0x000A 0x0017 0x001C 0x000B 0x0011 0x0003 0x0014 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBASK 3 continued IBASK 3 Table 5 2 ibask Board Configuration Parameter Options Options Options Constants Values Returned Information IbaPAD 0 0001 The current primary address of the board See ibpad IbaSAD 0x0002 The current secondary address of the board See ib
183. of device Syntax int ibbna intud char bname ud specifies a device bname specifies the new access board to be used in all device calls to that device ibbna is needed only to alter the board assignment from its configuration setting The assigned board is used in all subsequent device functions used with that device until ibbna is called again ibonl or ibfind is called or the system is restarted Device Function Example Associate the device with the interface board gpibO0 dvm ibfind dev10 ibbna gpib0 National Instruments Corp 5 21 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBCAC 3 IBCAC 3 Purpose Become Active Controller Syntax int ibcac intud int v ud specifies an interface board If v is non zero the GPIB board takes control synchronously with respect to data transfer operations otherwise the GPIB board takes control immediately asynchronously To take control synchronously the GPIB board asserts the ATN signal without corrupting data being transferred If a data handshake is in progress the take control action is postponed until the handshake is complete if a handshake is not in progress the take control action is done immediately Synchronous take control is not guaranteed if an ibrd or ibwrt operation completed with a timeout or error Asynchronous take control should be used in situations where it appears to be impo
184. of the board Identical to ibtmo Default determined by ibconf IbcEOT 0x0004 Changes the data termination mode for write operations Identical to ibeot Default determined by ibconf IbcPPC 0x0005 Configures the board for parallel polls Identical to board level ibppc Default zero IbcAUTOPOLL 0x0007 zero Disable automatic serial polling non zero Enable automatic serial polling Default determined by ibconf Refer to the Automatic Serial Polling section of this chapter for more information about automatic serial polling continues NI 488 2M Reference Manual 5 28 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBCONFIG 3 continued IBCONFIG 3 Table 5 4 ibconfig Board Configuration Parameter Options Continued Constants Values Legal Values IbcCICPROT 0x0008 zero Disable the CIC protocol non zero Enable the CIC protocol Default zero IbcIRQ 0x0009 zero Do not use interrupts non zero Use interrupts Default non zero IbcSC 0x000A Request or release system control Identical to ibrsc EN adl Default determined by ibconf IbcSRE 0x000B Assert the Remote Enable REN line Identical to ibsre IbcEOSrd 0x000C zero Ignore EOS character during read operations non zero Terminate read operation when the character read matches the EOS character Default determined by ibconf IbcEOSwrt 0x000D zero Do not assert EOI with
185. ommands PPC Parallel Poll Configure PPE Parallel Poll Enable PPU Parallel Poll Unconfigure Parallel poll constants are defined in the appropriate declaration file Device Function Example Remotely configure the device 1crmtr to respond positively on DIO3 if its individual status bit is 1 and then parallel poll all configured devices ibppc lcrmtr Ox6A ibrpp lcrmtr amp ppr National Instruments Corp 5 67 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBRPP 3 continued IBRPP 3 Board Function Examples 1 Remotely configure the board brdo at listen address hex 23 ASCII to respond positively on DIO3 if its individual status bit is 1 and then parallel poll all configured devices cmd 0 UNL cmd 1 0x40 cmd 2 0x23 cmd 3 PPC cmd 4 PPE S 2 cmd 5 UNL ibemd brd0 cmd 6 ibrpp brd0 amp ppr 2 Disable and unconfigure all GPIB devices from parallel polling using the PPU hex 15 command ibcmd gpib0 x15 1 NI 488 2M Reference Manual 5 68 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBRSC 3 IBRSC 3 Purpose Request or release system control Syntax int ibrsc intud int v ud specifies an interface board If v is non zero functions requiring System Controller capability are subsequently allowed If v is zero functions requiring System Controller c
186. on If ud specifies a device the same board functions as the device ibwrt function are performed automatically It terminates on similar conditions as ibwrt When the ibwrtf function returns ibsta holds the latest device status ibcnt is the number of bytes written and if the ERR bit in ibsta is set iberr is the first error detected NI 488 2M Reference Manual 5 68 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBWRTF 3 continued IBWRTF 3 Board IBWRTF Function If ud specifies an interface board the board ibwrt function writes to a GPIB device that is assumed to be already properly addressed An EADR error results if the board is CIC but has not been addressed to talk with the ibcmd function An EABO error results if for any reason the read operation does not complete within the time limit An ENOL error occurs if there are no Listeners on the bus when the data bytes are sent Device Function Example Write data to the device from the file rdrdata ibwrtf rdr rdrdata Board Function Examples Write data to the device at listen address hex 2C ASCII from the file rdrdata and then unaddress ibcmd brd0 3 ibwrtf brdO rdrdata National Instruments Corp 5 89 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 C GPIB Programming Examples These examples illustrate the programming steps that could b
187. on with correct ibic function syntax 5 filename is the pathname of a file that contains ibic functions to be executed 6 string consists of a list of ASCII characters octal or hex bytes or special symbols The entire sequence of characters must be enclosed in quotation marks An octal byte consists of a backslash character followed by the octal value For example octal 40 would be re presented by 040 A hex byte consists of a backslash character and a character x followed by the hex value For example hex 40 would be represented by x40 The two special symbols are r fora carriage return character and n for a linefeed character These symbols provide a more convenient method for inserting the carriage return and linefeed characters into the string as shown in this string F3R5T1 r n Since the carriage return can be represented equally Ww 7 n HEL ell in hex xD and r are equivalent strings indicates a board number for example n 1 for gpib1 P Display Help Information The HELP function gives causal information about ibic and its functions to be displayed on the screen Re The peat Previous Function function causes the most recent function executed to be repeated A table showing a progression of screen commands and their meanings follows National Instruments Corp 6 17 NI 488 2M Reference Manual ibic Chapter 6 Table 6 5 Repeating a Previous Function gpib0 ibsic Sen
188. orm and then call National Instruments for technical support By completing this form before calling National Instruments you will save yourself time The form contains the items of information that the applications engineers require from you in order to solve your problem To complete the form briefly jot down the information requested on the line to the right of the item By completing this form accurately you make it possible for our applications engineers to answer your questions accurately and efficiently National Instruments Products e NI 488 2M Software Revision Number on Disk Application Programming Language BASICA QuickBASIC C Pascal and so on Programming Language Interface Revision Type of National Instruments GPIB boards installed and their respective hardware settings Interrupt DMA Base I O Board Type Level Channel Address continues Other Products Computer Make and Model e Microprocessor e Clock Frequency Type of Monitor Card Installed Operating System Version Other Boards in System Basel O Address of Other Boards DMA Channels of Other Boards Interrupt Level of Other Boards Documentation Comment Form National Instruments encourages you to comment on the documentation supplied with our products This information helps us provide quality products to meet your needs Title NI 488
189. preventing visibility of the SRQI bit in status words for both board calls and device calls If you choose to look for SRQI in your program you must disable Autopolling Board functions are also incompatible with Autopolling refer to Chapter 3 for a description of board calls If Autopolling were to occur after a board call it could in some cases undo the effect of the call For example if SRQ were to become asserted immediately after an ibcmd call had been made to address a device Autopoll addressing of other devices for serial polls would destroy your intentions of addressing the device with which you must communicate For this reason the driver disables Autopolling whenever a board call is made and turns it back on once the application program makes a device call actually Autopolling is turned on at the end of the subsequent device call Internal Driver Operation If Autopolling is enabled whenever SRQ is asserted on the IEEE 488 bus all online devices that is all devices that have been opened using ibfind or ibdev connected to the GPIB interface board that detected the request are serial polled by the driver until one of the following events occur e SRQ becomes unasserted e All online devices have been polled since the last positive response and SRQ still remains asserted Once this has occurred a stuck SRQ state is in effect inside the driver If this state is reached during an ibwait for ROS the ESRQ error is report
190. r a full 8 bit binary byte can be used The NI 488 2M driver terminates reads and writes according to the value of the termination parameter For reads STOPend will terminate the read operation on the END message If the termination parameter is a character the read operation terminates when that character is received For writes the termination parameter may be either NLend DABend or NULLend NLend sends NL with END after the last data byte has been sent DABend sends END with the last data byte to be sent and NULLend simply sends the data bytes with no END message National Instruments Corp 3 17 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 C Programming Information The following discussion contains information for programming the driver functions in C C Language Files The NI 488 software distribution medium contains the following files which are relevant to programming in C e ugpib h isa file containing useful variable and constant declarations e cib c orin some cases cib o is the C language interface library for the NI 488 2 functions Programming Preparations for C Include the following C statement at the beginning of your application program include ugpib h The compiled C application program written is linked with cib o to produce an executable file Refer to the Getting Started manual included with your NI 488 2M driver for instructions on creating and using the cib
191. r devices to receive data bytes SetRWLS board addresslist Place particular devices 1 in the Remote with Lockout state TestSRQ board result Determine the current state of the SRQ line TestSys board addresslist Cause devices to conduct resultlist self tests Trigger board address Trigger a single device Triggerlist board addresslist Trigger multiple devices WaitSRQ board result Wait until a device asserts Service Request NI 488 2 Routine Descriptions The remainder of this chapter contains a detailed description of each NI 488 2 routine with examples in C The descriptions are listed alphabetically for easy reference To the right of each routine notice the number 3 in parentheses 3 This number is a UNIX convention It identifies the type of function in this case a routine and also refers you to a particular section in your UNIX Reference Pages in this case Section 3 National Instruments Corp 4 7 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 AllSpoll 3 AllSpoll 3 Purpose Serial Poll all devices Syntax void 115 11 int board Addr4882 t addresslist short resultlist board specifies a board number The GPIB devices whose addresses are contained in the address array are serial polled and the responses are stored in the corresponding elements of the resultlist array The parameter addresslist is an array of address integers of
192. racter is ignored during read operations non zero Read operation is terminated by the EOS character See ibeos IbaEOS wrt 0x000D zero The EOI line is not asserted when the EOS character is sent during a write operation non zero The EOI line is asserted when the EOS character is sent during a write operation See ibeos continues NI 488 2M Reference Manual 5 14 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBASK 3 continued IBASK 3 Table 5 2 ibask Board Configuration Parameter Options Continued Options Options Constants Values Returned Information IbaEOScmp OxO00E zero A 7 bit compare is used for all EOS comparisons non zero An 8 bit compare is used for all EOS comparisons See ibeos IbaEOSchar 0x000F The current EOS character of the board See ibeos IbaPP2 0x0010 zero The board is in PP1 mode remote parallel poll configuration non zero The board is in PP2 mode local parallel poll configuration IbaTIMING 0 0011 The current bus timing of the board 1 Normal timing T1 delay of 2 us 2 High speed timing T1 delay of 500 ns 3 Very high speed timing T1 delay of 350 ns IbaDMA 0x0012 zero The board does not use DMA for GPIB transfers non zero The board uses for GPIB transfers See ibdma continues National Instruments Corp 5 15 NI 488 2M Reference Manual NI 488M Software Chara
193. rint if iberr ESRQ print if iberr ETAB print printf ibcnt d n printf An y software ibonl 0 0 National Instruments Corp Fh Fh Fh Fh Fh Fh Fh Fh ESAC EABO ENEB ECAP EFSO EBUS ESTB ESRO ETAB ibcnt 4 43 NI 488 2M Software Characteristics and Routines lt Not Sys Ctrlr 1n Op aborted in No GPIB board Wn No capability Nn File sys error gt n Command gt Status byte lost gt n lt SRQ stuck on Mn Table Overflow Mn Call the ibonl function to disable the hardware and NI 488 2M Reference Manual Chapter 5 NI 488M Software Characteristics and Functions This chapter contains a discussion of the NI 488 functions C language programming examples are given General Programming Information The following facilities or operations are common to all programming languages e Status Word ibsta e Error Codes iberr e Count Variable ibcnt e Read and Write Termination e Device Functions e Automatic Serial Polling You should understand these topics thoroughly to take full advantage of the NI 488 2M driver s capabilities Refer to Chapter 3 Understanding the NI 488 2M Software for information on the status word ibsta the error variable iberr and the count variable ibcnt These variables are updated with each function call to reflect the status of
194. roblems you might have as well as a form you can use to comment on the product documentation Filling out a copy of the Technical Support Form before contacting National Instruments helps us help you better and faster National Instruments provides comprehensive technical assistance around the world In the U S and Canada applications engineers are available Monday through Friday from 8 00 a m to 6 00 p m central time In other countries contact the nearest branch office You may fax questions to us at any time Corporate Headquarters 512 795 8248 Technical Support Fax 512 794 5678 Branch Offices Phone Number Fax Number Australia 03 9 879 9422 03 9 879 9179 Austria 0662 45 79 90 0 0662 45 79 90 19 Belgium 02 757 00 20 02 757 03 11 Canada Ontario 519 622 9310 Canada Quebec 514 694 8521 514 694 4399 Denmark 45 76 26 00 45 76 26 02 Finland 90 527 2321 90 502 2930 France 1 48 14 24 24 1 48 14 24 14 Germany 089 741 31 30 089 714 60 35 Hong Kong 2645 3186 2686 8505 Italy 02 413091 02 41309215 Japan 03 5472 2970 03 5472 2977 Korea 02 596 7456 02 596 7455 Mexico 95 800 010 0793 5 520 3282 Netherlands 0348 433466 0348 430673 Norway 32 84 84 00 32 84 86 00 Singapore 2265886 2265887 Spain 91 640 0085 91 640 0533 Sweden 08 730 49 70 08 730 43 70 Switzerland 056 200 51 51 056 200 51 55 Taiwan 02 377 1200 02 737 4644 U K 01635 523545 01635 523154 National Instruments Corp 1 NI 488 2M Reference Manual Technical Suppor
195. roduction to the NI 488 2 Routines A new set of NI 488 2 routines have been added to the NI 488 2M software to take advantage of the IEEE 488 2 1992 standard The NI 488 2 routines are described in Chapter 4 NI 488 2M Software Characteristics and Routines These routines are completely compatible with the Controller sequences and protocols defined in the IEEE 488 2 1992 standard IEEE 488 2 is the standard upon which the new generation of test systems will be built because it enhances system compatibility and configurability by defining data formats status reporting Controller capabilities and commands and a general command set to which all IEEE 488 2 instruments must adhere IEEE 488 2 is also the basis of the Standard Commands for Programmable Instrumentation SCPI so all SCPI instruments must be IEEE 488 2 compatible The NI 488 2 routines address these system programming benefits of IEEE 488 2 National Instruments Corp 3 1 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 The syntax of the NI 488 2 routines resembles the naming conventions used in the standard These routines let you take full advantage of IEEE 488 2 especially when a complete IEEE 488 2 system of Controllers and instruments is used There are routines that find all of the Listeners on the bus configure the attached instruments find a device requesting service determine the state of the SRQ line wait for SRQ to be asserted and addres
196. room to hold all the addresses of the Listeners found In the case of FindRQS it means that none of the devices in the given table were requesting service NI 488 2M Reference Manual 3 16 National Instruments Corp Chapter 3 Understanding the NI 488 2M Software Count Variable ibcnt The count variable is updated after each read write or command function with the number of bytes actually transferred by the operation The count variable is also updated by many of the NI 488 2 routines ibcnt isan integer value Read and Write Termination The IEEE 488 specification defines two methods of identifying the last byte of device dependent data messages The two methods permit a Talker to send data messages of any length without the Listener s knowing in advance the number of bytes in the transmission The two methods are as follows e END message In this method the Talker asserts the EOI End Or Identify signal simultaneously with transmission of the last data byte By design the Listener stops reading when it detects a data message accompanied by EOI regardless of the value of the byte e End Of String EOS character In this method the Talker uses a special character at the end of its data string With IEEE 488 2 this EOS character is explicitly designated as a new line NL ASCII 10 hex 0A character By prior arrangement the Listener stops receiving data when it detects that character Either a 7 bit ASCII character o
197. s Corp 5 47 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBLINES 3 IBLINES 3 Purpose Return the status of the GPIB control lines Syntax int iblines int ud int clines ud is a board descriptor A valid mask is returned along with the GPIB control line state information in clines The low order byte bits 0 through 7 of clines contains a mask indicating the capability of the GPIB interface board to sense the status of each GPIB control line The upper byte bits 8 through 15 contains the GPIB control line state information The pattern of each byte is as follows Bees ESE ss aw nc em nc o To determine if a GPIB control line is asserted first check the appropriate bit in the lower byte to determine if the line can be monitored If the bit can be monitored indicated by a 1 in the appropriate bit position then check the corresponding bit in the upper byte If the bit is set 1 the corresponding control line is asserted If the bit is clear 0 the control line is unasserted For iblines to return valid data a well behaved IEEE 488 bus must exist A well behaved IEEE 488 bus is a bus in which all attached devices are following the IEEE 488 specification NI 488 2M Reference Manual 5 48 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBLINES 3 continued IBLINES 3 Device Board Function Example
198. s multiple devices If your application plans call for IEEE 488 2 it is best to use the NI 488 2 routines Some programming implementations such as configuring timeout values or monitoring all of the bus management lines are not specifically described in IEEE 488 2 For these requirements the traditional NI 488 board functions can be used along with the NI 488 2 routines The necessary NI 488 board functions are described in the Relationship of NI 488 2 Routines to NI 488 Calls section at the beginning of Chapter 4 NI 488 2M Software Characteristics and Routines Introduction to the NI 488 Functions The NI 488 functions consist of high level or device functions that hide much of the GPIB management operations and low level or board functions that offer you complete control over the GPIB Typically only a few high level functions are needed for most application programs These functions are described in Chapter 5 NI 488M Software Characteristics and Functions Device Functions Device functions are high level functions that are easy to learn and use These functions free you from having to know the GPIB protocol or bus management details involved They automatically execute sequences of commands that handle bus management operations required to perform activities such as reading from and writing to devices or polling them for status Device functions access a specific device and take care of the addressing and bus management protocol
199. sad IbaTMO 0x0003 The current I O timeout of the board See ibtmo IbaEOT 0x0004 zero The GPIB EOI line is not asserted at the end of a write operation non zero EOI is asserted at the end of a write operation See ibeot IbaPPC 0x0005 The current parallel poll configuration information of the board See ibppc IbaAUTOPOLL 0x0007 zero Automatic serial polling is disabled non zero Automatic serial polling is enabled Refer to the Automatic Serial Polling section of this chapter for more information about automatic serial polling IbaCICPROT 0 0008 zero The CIC protocol is disabled i ddl non zero The CIC protocol is enabled IbaIRQ 0x0009 zero Interrupts are not enabled pcc non zero Interrupts are enabled continues National Instruments Corp 5 13 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBASK 3 continued IBASK 3 Table 5 2 ibask Board Configuration Parameter Options Continued Options Options Constants Values Returned Information IbaSC 0x000A zero The board is not the System Controller non zero The board is the System Controller See ibrsc IbaSRE 0 000 zero The board does not automatically assert the GPIB REN line when it becomes the System Controller non zero The board automatically asserts REN when it becomes the System Controller See ibrsc and ibsre IbaEOSrd Ox000C zero The EOS cha
200. sed to program a representative IEEE 488 instrument from your personal computer using the NI 488 2 driver routines and NI 488 driver functions respectively The applications are written using ibic commands NI 488 2 Routines To set up ibic for NI 488 2 calls use the set command as follows set 488 2 488 2 0 NI 488 2M Reference Manual 6 20 National Instruments Corp Chapter ibic Send the interface clear message IFC to all devices This clears the bus You should check for ERR after each GPIB function call 488 2 0 SendIFC 0120 cmpl cic Clear the device The device is assumed to be on the GPIB bus at primary address 2 488 2 0 DevClear 2 0138 cmpl cic atn tacs count 1 Write the routine range and trigger source information to the device a digital voltmeter 488 2 0 Send 2 F3R7T3 DABend 0128 cmpl cic tacs count 6 Trigger the device 488 2 0 Trigger 2 0138 cmpl cic atn tacs count 1 Wait for the meter to request service by asserting the SRQ bus line and then read the meter s status byte 488 2 0 WaitSRQ 1138 srqi cmpl cic atn tacs SRQ line is asserted 488 2 0 ReadStatusByte 2 0174 cmpl rem cic atn lacs Poll 2 gt 0x0040 decimal 32 Read the meter s data 488 2 0 Receive 2 20 STOPend 2164 end cmpl rem cic lacs count 20 Od 4e 44 43 56 2d 30 NDCV 30 30 2e 30 3034 37 45 00 0047E 2b 30 0 0a 0 National
201. ssages 3 17 device dependent messages D 1 disable auto serial polling 2 12 disconnecting a device 2 4 DMA 3 15 controller 3 15 enable disable 5 5 mode 2 13 transfers 2 13 driver See device driver DTAS 3 7 3 10 3 11 3 19 E EABO 3 11 3 14 to 3 15 B 3 to B 4 EADR 3 11 3 14 B 2 EARG 3 11 3 14 B 3 EBTO 3 2 3 15 B 4 EBUS 3 12 3 15 to 3 16 B 5 ECAP 3 12 3 15 5 ECIC 3 11 3 12 to 3 13 B 1 ECIC error 5 2 editing board or device characteristics 2 5 EDMA 3 11 3 15 B 4 EDVR 3 11 3 12 EFSO 3 12 3 15 B 5 electrical characteristics D 5 to D 8 EnableLocal 3 9 4 5 4 11 6 11 National Instruments Corp Index 3 NI 488 2M Reference Manual Index EnableRemote 3 14 4 5 4 12 6 11 END 3 7 3 8 3 11 3 15 END message 2 8 3 17 enable disable 5 5 End Of String See EOS ENEB 3 11 3 15 B 4 ENOL 3 11 3 13 B 1 to B 2 EOI 2 5 3 8 3 17 D 4 set EOI with EOS on write 2 11 set EOI with last byte of write 2 11 set with last byte of write 2 11 EOS 2 5 2 8 3 8 3 17 adding in ibic 6 8 change disable mode 5 5 EOS byte 2 10 to 2 11 set EOI with EOS on write 2 11 terminate READ on EOS 2 11 type of compare on EOS 2 11 ERR 3 7 3 8 3 11 error codes See also iberr condition 3 8 in ibic 6 15 variable 3 11 to 3 12 See also iberr errors common B 1 to B 7 ESAC 3 11 3 14 B 3 ESRQ 3 12 3 16 5 3 5 4 B 6 ESTB 3 12 3 16 5 3 B 6 ETAB 3 12
202. ssible to gain control synchronously for example after a timeout error It is generally not necessary to use the ibcac function in most applications Functions such as ibcmd and ibrpp that require the GPIB board to take control do so automatically The ECIC error results if the GPIB board is not CIC Board Function Example 1 Take control immediately without regard to transfers in progress ibcac brd0 0 2 Take control synchronously and assert ATN following a read operation int brd0 brd0 ibfind gpib0 ibrd brd0 rd 512 ibcac brd0 1 NI 488 2M Reference Manual 5 22 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBCLR 3 IBCLR 3 Purpose Clear specified device Syntax int ibclr int ud ud specifies a device The ibcir function clears the internal or device functions of a specified device ibclr calls the board function ibcmd to send the following commands using the designated access board e Talk address of access board e Unlisten UNL e Listen address of the device e Secondary address of the device if applicable e Selected Device Clear SDC Other command bytes may be sent as necessary Refer to JBCMD for additional information Refer also to the discussion of device functions in Chapter 3 Understanding the NI 488 2M Software Device Function Example Clear the device vmt r int vmtr vmtr ibfind dev3 open instrument
203. t Form Photocopy this form and update it each time you make changes to your software or hardware and use the completed copy of this form as a reference for your current configuration Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently If you are using any National Instruments hardware or software products related to this problem include the configuration forms from their user manuals Include additional pages if necessary Name Company Address Fax Phone Computer brand Model Processor Operating system Speed MHz RAM MB Display adapter Mouse yes no Other adapters installed Hard disk capacity MB Brand Instruments used National Instruments hardware product model Revision Configuration continues National Instruments software product Version Configuration The problem is List any error messages The following steps will reproduce the problem NI 488 2M Hardware and Software Configuration Form This appendix contains the form you use if you have completed all the necessary steps for installing and configuring the hardware and or software and the hardware and or software installation and configuration still fail Complete the following f
204. t is not it is possible to perform an ibwait CIC call to delay further processing until control is passed to the board ENOL usually occurs when a write operation is attempted with no Listeners addressed For a device write this error indicates that the GPIB address configured for that device in the driver does not match the GPIB address of any device connected to the bus that the GPIB cable is not connected to the device or that the device is not powered on This situation can be corrected by either attaching the appropriate device to the GPIB modifying the address of an already attached device calling ibpad and ibsad if necessary to match the configured address to the device switch settings or using the ibconf configuration utility to reassign the proper GPIB address to the device in the driver For board functions an ibcmd is generally necessary to address devices before a board ibwrt function is executed Be sure that the proper listen address is in the ibcmd argument string and that no Unlisten hex 3F command follows it ENOL may occur in situations in which the GPIB board is not the CIC and the Controller asserts ATN before the write call in progress has ended The remedy is either to reduce the write byte count to that which is expected by the Controller or to resolve the situation on the Controller s end National Instruments Corp 3 13 NI 488 2M Reference Manual Understanding the NI 488 2M Software Chapter 3 EA
205. ta terree 3 6 Error Variable ib ertt zustimmen 3 11 Count Variable 1 nre 3 17 Read and Write Termination eene 3 17 C Programming Information esee 3 18 C Language Files 5 nete netter 3 18 Programming Preparations for sess 3 18 Signal Interrupting tete eet tpe 3 18 NI 488 2M Reference Manual vi National Instruments Corp Contents Chapter 4 NI 488 2M Software Characteristics and Routines 4 1 OVEIVIEW os ert E ine RE 4 1 General Programming Information eee 4 1 Relationship of NI 488 2 Routines to NI 488 Calls 4 4 TIME OUtS tee eme ud secon etiara t e eee 4 5 CNI 488 2 Routines e eik i e rii 4 5 NI 488 2 Routine Descriptions 4 7 AUIS poll 3 e a itte e er 4 8 DevClear 3 ine e eive e a EE aE EE eat 4 9 DevClearlist 3 iieri exe et retenti De 4 10 BEnableLocal 3 i Eee eret ies 4 11 EnableReimote 3 a Rien teret 4 12 bindESti 3 15S Eee Dn MOESIA 4 13 FindROS 3 at 4 14 PassControl 3 5 hereto et 4 15 BPoll 3 ERAT eA ern este RH 4 16 PPollConfig 3 oie terere ee ep eerie dede 4 17 PPollUriconfig GY ses x oot erre tere es 4 18 RcyRespMSg 3 2 en eene fee eco fe ter epis 4 19 ReadStatusByte
206. ta across the GPIB ibrd dmm rd 13 The variable rd holds the ASCII string representing the voltage measurement taken by the meter NI 488 2M Reference Manual 5 6 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions Step 6 Analyzing and Presenting the Acquired Data Once the data has been acquired from the GPIB all of the analysis and presentation functions of the programming language can be used to manipulate the data Instead of reading just one voltage measurement from the meter you could have read 10 values and calculated their average The following code would replace the code in the last two lines of Step 5 for sum 0 x 0 x lt 10 ibtrg dmm ibrd dmm rda 3 sum sum atof rd printf The average voltage is f sum 10 The Complete Application Program The complete application program is as follows include lt stdio h gt include ugpib h main int dmm x double sum char rd 13 dmm ibdev 0 1 0 12 1 0 ibclr dmm ibwrt dmm F1ROS2T4 8 for sum 0 x 0 x lt 10 x ibtrg dmm ibrd dmm rd 13 sum sum rd printf The average voltage is f sum 10 National Instruments Corp 5 9 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 NI 488 Function Descriptions The remainder of this chapter contains a detailed description of each
207. tem is initialized on the following three levels Bus initialization Remote Enable REN is asserted followed by Interface Clear IFC causing all devices to become unaddressed and the GPIB interface board the System Controller to become the Controller in Charge Message exchange initialization The Device Clear DCL message is sent to all connected devices This ensures that all 488 2 compatible devices can receive the Reset RST message that follows Device initialization RST message is sent to all devices whose addresses are contained in the addresslist argument This causes device specific functions within each device to be initialized Example Completely reset a GPIB system containing devices at addresses 8 9 and 10 Addr4882_t addresslist 4 8 9 10 NOADDR ResetSys 0 addresslist National Instruments Corp 4 23 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 Send 3 Send 3 Purpose Send data bytes to a single GPIB device Syntax void Send intboard Addr4882_t address char data long count int eotmode board specifies a board number The indicated GPIB device is addressed as a Listener the indicated board is addressed as a Talker and count data bytes contained in data are sent The count value is of type long Even though it is a long value in these languages however integer values and variables may also be passed eotmode is a fla
208. th that of a device ESAC 5 Error Condition board not System Controller as required Solutions e Run ibconf and make sure the board gpib0 gpibl is configured to be System Controller e Issue a board ibrsc function call with a value of 1 to request System Control EABO 6 Error Condition I O operation aborted Solutions e Check that the device is powered on National Instruments Corp B 3 NI 488 2M Reference Manual Common Errors and Their Solutions Appendix B e Verify proper cable connections Errors received from ibrd Some devices will not send data unless they have received data telling them what to send This is caused by devices having the capability of sending several types of data Issue an ibwrt to set up the device and then an ibrd to receive the information Ifyou have not changed any of the default EOS or EOI settings in ibconf the reads will terminate when the buffer is full or when EOI is set If your device sends an EOS termination character such as a carriage return rather than EOI then use ibconf to change the device characteristics ENEB 7 Error Condition Non existent GPIB board Solution e Runibconf and make sure the base I O address of the board matches the hardware address switch settings ibconf will display the proper switch settings for the selected base address EDMA 8 Error Condition indicates that a DMA hardware error occurred during an I
209. that is the object of the function See unit descriptor universal language interface A number that is used by the driver to temporarily identify a device or board that has been opened with the ibfind function The descriptor is not related to the GPIB address of the unit The GPIB command used to unaddress any active listeners The GPIB command used to unaddress an active talker National Instruments Corp 11 NI 488 2M Reference Manual Index Symbols Repeat Previous Function 6 17 to 6 18 Execute Indirect File function 6 19 Turn ON Display 6 18 Turn OFF Display function 6 18 A access board 2 3 5 5 names 2 8 addressing 2 6 2 8 3 13 See also listen address primary GPIB address secondary GPIB address talk address AllSpoll 4 8 6 11 application programs 2 14 example 5 9 ATN 3 7 3 9 3 14 D 4 auto serial polling 2 12 automatic serial poll 5 2 to 5 5 compatibility 5 4 autopolling See automatic serial polling auxiliary functions supported by ibic 6 16 to 6 20 B base I O address 2 8 3 15 board functions 3 3 to 3 4 3 7 5 4 example program 5 96 to 5 99 in ibic 6 23 to 6 25 buffered DMA transfers 2 14 bus initialization 4 23 bus management 3 2 4 2 4 3 byte count in ibic 6 16 National Instruments Corp Index 1 NI 488 2M Reference Manual Index C C 2 14 application programming See programming with NI 488 functions GPIB programming
210. the EOS character during writes operations non zero Assert EOI with the EOS character during writes Default determined by ibconf continues National Instruments Corp 5 29 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBCONFIG 3 continued IBCONFIG 3 Table 5 4 ibconfig Board Configuration Parameter Options Continued Options Options Constants Values Legal Values IbcEOScmp OxO00E zero Use 7 bits for the EOS character comparison non zero Use 8 bits for the EOS character comparison Default determined by ibconf IbcEOSchar OxO00F Any 8 bit value This byte becomes the new EOS character Default determined by ibconf IbcPP2 0x0010 zero PP1 mode remote parallel poll configuration non zero PP2 mode local parallel poll configuration Default zero IbcTIMING 0x0011 1 Normal timing delay of 2 us 2 High speed timing T1 delay of 500 ns 3 Very high speed timing T1 delay of 350 ns Default determined by ibconf The T1 delay is the GPIB Source Handshake timing IbcDMA 0x0012 Identical to ibdma Default determined by ibconf IbcReadAdjust 0x0013 0 No byte swapping 1 Swap pairs of bytes during a read Default zero continues NI 488 2M Reference Manual 5 30 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions IBCONFIG 3 continued IBCONFIG 3 Table 5 4
211. the Controller before starting a measurement TRIGGER 2 and to assert the IEEE 488 Service Request signal line SRQ when the measurement has been completed and the meter is ready to send the result SRE 16 5 For each measurement Send the TRIGGER command to the multimeter The ibwrt command VAL1 instructs the meter to send the next triggered reading to its IEEE 488 output buffer NI 488 2M Reference Manual 5 90 National Instruments Corp Chapter 5 NI 488M Software Characteristics and Functions 6 b Wait until the DVM asserts Service Request SRQ to indicate that the measurement is ready to be read c Serial poll the DVM to determine if the measured data is valid or if a fault condition exists You can find out by checking the message available bit bit 4 in the status byte d Ifthe data is valid read 10 bytes from the DVM End the session The example programs that follow are based on these assumptions The GPIB board is the designated System Active Controller of the GPIB There is no change to the GPIB board default hardware settings The only changes made to the software parameters are those necessary to define the device DVM at primary address 1 There is only one GPIB board in use and it is designated gpibO The primary listen and talk addresses of GPIBO are hex 20 ASCII space character and hex 40 ASCII character respectively National Instruments Corp 5 91 NI 488 2M Ref
212. the device or board just accessed Device Functions Device functions are those functions in which the unit descriptor identifies a device rather than an interface board refer to Chapter 3 Understanding the NI 488 2M Software for a discussion of boards and devices There are some activities common to all device functions that you should understand thoroughly National Instruments Corp 5 1 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 In a single board configuration there is only one GPIB interface board in use When the first device function of a program is executed the driver initializes the IEEE 488 bus by sending the Interface Clear IFC single line interface message The Remote Enable REN line on the IEEE 488 bus is also asserted and the Local Lockout LLO multiline interface message is sent to all devices on the IEEE 488 bus to place them in a lockout state Furthermore the device may be addressed to listen and then unaddressed before certain functions are executed This step ensures that the device is in remote program mode In a multiboard configuration more than one GPIB board is in use The process is the same as in the preceding description with the exception that each IEEE 488 bus is initialized by its associated GPIB interface board when the first device on that IEEE 488 bus is accessed by a device function The preceding descriptions assume that the GPIB board is the Syste
213. ther in contract or tort including negligence Any action against National Instrument must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this book may not be copied photocopied reproduced or translated in whole or in part without the prior written consent of National Instruments Corporation Trademarks NI 488 2M is a trademark of National Instruments Corporation Product names listed are trademarks of their respective manufacturers Company names listed are trademarks or trade names of their respective companies WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS National Instruments products are not designed with components and testing intended to ensure a level of reliability suitable for use in treatment and diagnosis of humans Applications of National Instruments products involving medical or clinical treatment can create a potenti
214. thods B and C together determine when write operations send the END message If Method B alone is chosen the END message is sent automatically with the EOS byte when the low seven bits of that byte match the low seven bits of the EOS character If Methods B and C are chosen a full 8 bit comparison is used National Instruments Corp 5 39 NI 488 2M Reference Manual NI 488M Software Characteristics and Functions Chapter 5 IBEOS 3 continued IBEOS 3 Note Defining an EOS byte for a device or board does not cause the driver to automatically send that byte when performing writes Your application program must include the EOS byte in the data string it defines Device IBEOS Function If ud specifies a device the options coded in v are used for all device reads and writes in which that device is specified Board IBEOS Function If ud specifies a board the options coded in v become associated with all board reads and writes Refer also to Device Function Example Send END when the linefeed character is written to the device dvm v XEOS n EOS information for ibeos ibeos dvm ibwrt 123 n 4 Board Function Examples 1 Program the interface board brdo to terminate a read on detection of the linefeed character hex 0A that is received within 200 bytes char rd 200 v REOS An ibeos brd0 v ibrd brd0O rd 200 NI 488 2M Reference Manual 5 40 Nat
215. tions into one function so that the user does not have to be concerned with bus management or other GPIB protocol matters See low level function The global variable that is updated after each I O function call to show the actual number of bytes sent or received ibcnt is a full 32 bit representation The NI 488 2M driver configuration program See configuration A global variable that contains the specific error code associated with a function call that failed The Interface Bus Interactive Control program is used to communicate with GPIB devices troubleshoot problems and develop your application A global variable that is updated at the end of each function call with important status information such as the occurrence of an error Institute of Electrical and Electronic Engineers Standard 488 1978 National Instruments Corp G 5 NI 488 2M Reference Manual Glossary IFC or interface clear interface message I O or input output address ISO ist L LAD or listen address language interface listen address listener LLO or local lockout NI 488 2M Reference Manual G 6 A GPIB line used by the system controller to initialize the bus See DCL and SDC A broadcast message sent from the controller to all devices and used to manage the GPIB Common interface messages include Interface Clear listen addresses talk addresses and Serial Poll Enable Disable See data or device dependent message
216. tten in C The target instrument is a digital voltmeter DVM This instrument is otherwise unspecified that is it is not DVM manufactured by any particular manufacturer The purpose here is to explain how to use the driver to execute NI 488 2 programming and control sequences and not how to determine those sequences l Initialize the IEEE 488 bus and the interface board Controller circuitry so that the IEEE 488 interface for each device is quiescent and so that the interface board is Controller In Charge and is in the Active Controller State CACS 2 Find all of the Listeners a Findall of the instruments attached to the IEEE 488 bus b Create an array that contains all of the IEEE 488 primary addresses that could possibly be connected to the IEEE 488 bus c Find out which if any device or devices are connected 3 Send an identification query to each device for identification 4 Initialize the instrument as follows a Clear the multimeter b Send the IEEE 488 2 Reset command to the meter National Instruments Corp 4 37 NI 488 2M Reference Manual NI 488 2M Software Characteristics and Routines Chapter 4 5 Instruct the meter to measure volts alternating current VAC using auto ranging AUTO to wait for a trigger from the Controller before starting a measurement TRIGGER 2 and to assert the IEEE 488 Service Request signal line SRQ when the measurement has been completed and the meter is ready to send the res
217. ult SRE 16 6 For each measurement Send the TRIGGER command to the multimeter The command VAL1 instructs the meter to send the next triggered reading to its IEEE 488 2 output buffer b Wait until the DVM asserts Service Request SRQ to indicate that the measurement is ready to be read c Read the status byte to determine if the measured data is valid or if a fault condition exists You can find out by checking the message available bit bit 4 in the status byte d Ifthe data is valid read 10 bytes from the DVM 7 the session NI 488 2M Reference Manual 4 38 National Instruments Corp Chapter 4 NI 488 2M Software Characteristics and Routines Example Program NI 488 2 Routines Link this program with cib o x include lt stdio h gt include lt stdlib h gt include lt string h gt include ugpib h Position of the Message Available bit define MAVbit 0x10 char buffer 101 int loop m num_listeners SRQasserted double sum Addr4882 t instruments 32 result 31 fluke short statusByte void gpiberr char msg gpib error function main system clear Your GPIB board must be the Controller In Charge to perform the Find All Listeners protocol SendIFC 0 if ibsta amp ERR gpiberr SendIFC Error exit 1 Create an array with all of the valid GPIB primary addresses This array will be given to the Find
218. ult setting for the base I O address and interrupt setting Check the Getting Started manual that came with your interface board for these settings Device and Board Characteristics The following explanations are for board and device characteristics in ibconf that are common to all revisions of the NI 488 2M driver For information on characteristics specific to a given driver check the Getting Started manual that came with your interface board In addition extensive help for each characteristic is displayed on the ibconf screen while the cursor is positioned in a field Most of the following characteristics apply to both devices and boards although some as indicated only apply to boards NI 488 2M Reference Manual 2 6 National Instruments Corp Chapter 2 Installation and Configuration of NI 488 2M Software Primary GPIB Address All devices and boards must be assigned unique primary addresses in the range from hex 00 to hex 1 0 to 30 decimal The driver automatically forms a listen address by adding hex 20 to the primary address It forms the talk address by adding hex 40 to the primary address For example a primary address of hex 10 would have a listen address of hex 30 and a talk address of hex 50 The GPIB primary address of any device is set within that device either with hardware switches or a software program This address and the address listed in ibconf must correspond Refer to the device documentation for instructions
219. umber must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this manual is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN N ATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whe
220. unction ESTB 15 occurs only during the ibrsp function ESTB indicates that one or more serial poll status bytes that were received due to automatic serial polls have been discarded for lack of room to store them Several older status bytes are available however the oldest is being returned by the ibrsp call If your application cannot tolerate missing even one status byte the remedy is to disable Automatic Serial Polling using ibconf ESRQ 16 ESRQ occurs only during the Wait SRQ routine or ibwait function ESRQ indicates that a wait for RQS is not possible because the GPIB SRQ line is stuck on The usual reason for this situation is that some device that the driver is unaware of is asserting SRQ Because the driver does not know of this device it will never be serial polled and SRQ will never go away Another reason for this error is that a GPIB bus tester or similar equipment was forcing the SRQ line to be asserted or that there is a cable problem involving the SRQ line Although the occurrence of ESRQ signals a definite GPIB problem it does not affect GPIB operations except that the RQS bit cannot be depended on while the condition lasts ETAB 20 ETAB occurs only during the FindLstn and FindROS routines ETAB indicates that there was some problem with a table used by these functions In the case of FindLstn this is not an error condition but simply an advisory message which means that the given table did not have enough
221. ve correctly configured the device e For board write functions make sure the device is addressed properly using the function before the write call Verify that the low five bits of the listen address and if appropriate the secondary address used in the ibcmd call match the GPIB address es of the device and also that the listen address is in the range 20 through 3E hex 32 through 62 decimal and the secondary address is in the range 60 through 7E hex 92 through 126 decimal EADR 3 Error Condition GPIB board gpib0 or gpib1 is not addressed correctly Solutions e Use ibcmd to send the appropriate Talk or Listen address before attempting an ibwrt or ibrd e fcalling ibgts with the shadow handshake feature call ibcac to ensure that the GPIB ATN line is asserted NI 488 2M Reference Manual B 2 National Instruments Corp Appendix Common Errors and Their Solutions EARG 4 Error Condition Invalid argument to function call Solutions e Errors received from ibic Verify syntax in Chapter 6 of this manual ibic Make sure the GPIB address of the board in ibconf does not conflict with that of a device e Errors received when running your application program Verify syntax in Chapter 4 NI 458 2M Software Characteristics and Routines and Chapter 5 NI 458M Software Characteristics and Functions in this manual Make sure the GPIB address of the board in ibconf does not conflict wi
222. ves paths directories programs subprograms subroutines device names functions variables filenames and extensions and for statements and comments taken from program code Bold text in this font denotes the messages and responses that the computer automatically prints to the screen Italic text in this font denotes that you must supply the appropriate words or values in the place of these items Angle brackets enclose the name of a key on the keyboard for example Break A hyphen between two or more key names enclosed in angle brackets denotes that you should simultaneously press the named keys for example lt Ctrl Alt Del gt About This Manual IEEE 488 and IEEE 488 and IEEE 488 2 refer to the IEEE 488 2 ANSI EEE Standard 488 1 1987 and ANSI IEEE Standard 488 2 1992 respectively which define the GPIB Abbreviations acronyms metric prefixes mnemonics symbols and terms are listed in the Glossary Customer Communication National Instruments wants to receive your comments on our products and manuals We are interested in the applications you develop with our products and we want to help if you have problems with them To make it easy for you to contact us this manual contains comment and configuration forms for you to complete These forms are in Appendix E Customer Communication at the end of this manual Chapter 1 Introduction Welcome to the world of the General Purpose Interface Bus GPIB We b
223. when the GPIB board participates in a parallel poll that is conducted by another device that is the Active Controller The Active Controller conducts a parallel poll by asserting the EOI signal to send the Identify IDY message While this message is active each device which has been configured to participate in the poll responds by asserting a predetermined GPIB data line either true or false depending on the value of its local ist bit The GPIB board for example can be assigned to drive the DIO3 data line true if ist 1 and false if ist 0 conversely it can be assigned to drive DIO3 true if ist 0 and false if ist 1 The relationship between the value of ist the line that is driven and the sense at which the line is driven is determined by the Parallel Poll Enable PPE message in effect for each device The GPIB board is capable of receiving this message either locally via the ibppc function or remotely via acommand from the Active Controller Once the PPE message is executed the ibist function changes the sense at which the line is driven during the parallel poll and in this fashion the GPIB board can convey a one bit device dependent message to the Controller When ibist is called and an error does not occur the previous value of ist is stored in iberr Refer also to JBPPC Board Function Example 1 Set the individual status bit ibist brd0 1 2 Clear the individual status bit ibist brd0 0 National Instrument
224. wisted with ATN Shield Signal Ground Figure D 1 GPIB Connector and the Signal Assignment NI 488 2M Reference Manual D 6 National Instruments Corp Appendix Operation of the GPIB Figure D 2 Linear Configuration National Instruments Corp D 7 NI 488 2M Reference Manual Operation of the GPIB Appendix D Figure D 3 Star Configuration NI 488 2M Reference Manual D 8 National Instruments Corp Appendix Operation of the GPIB Configuration Requirements To achieve the high data transfer rate that the GPIB was designed for the physical distance between devices and the number of devices on the bus are limited The following restrictions are typical e maximum separation of four meters between any two devices and an average separation of two meters over the entire bus e A maximum total cable length of 20 meters e more than 15 devices connected to each bus with at least two thirds powered on Bus extenders are available from National Instruments for use when these limits must be exceeded Related Document For more information on topics covered in this section consult EEE Standard Digital Interface for Programmable Instrumentation ANSI JEEE Std 488 1 1992 National Instruments Corp D 9 NI 488 2M Reference Manual Appendix Customer Communication For your convenience this appendix contains forms to help you gather the information necessary to help us solve technical p
225. xample program written in C is developed step by step The example program uses device functions because they are the simplest functions and can be used for most applications This program configures a digital multimeter meter reads back 10 voltage measurements and computes the average of these measurements At the end of this example program an equivalent example program that uses board functions is shown Step 1 Initializing the System The first step in writing a C program is to load in the definitions of the NI 488 functions from a file that is provided on your distribution medium include lt stdio h gt include ugpib h main int dmm x double sum char rd 13 The input arguments to the ibdev subroutine are the board index number 0 for GPIBO the primary GPIB address of the device 1 the secondary GPIB address of the device 0 for none the timeout for the driver to use when communicating with the device 12 for 3 s send END message with last data byte when writing to device 1 for enable and EOS detection mode 0 for disable When ibdev is called the driver automatically initializes the GPIB by sending an Interface Clear IFC message and places the device in its remote programming state Step 2 Clearing the Device It is considered good practice to clear the device before you begin to configure the device for your application Clearing the device resets its internal functions to a known state
226. ynchronously control the transfer of message bytes among devices The process is called a three wire interlocked handshake and it guarantees that message bytes on the data lines are sent and received without transmission error NRFD not ready for data NRFD indicates when a device is ready or not ready to receive a message byte The line is driven by all devices when receiving commands and by Listeners when receiving data messages NDAC not data accepted NDAC indicates when a device has or has not accepted a message byte The line is driven by all devices when receiving commands and by Listeners when receiving data messages National Instruments Corp D 3 NI 488 2M Reference Manual Operation of the GPIB Appendix D DAV data valid DAV tells when the signals on the data lines are stable valid and can be accepted safely by devices The Controller drives DAV when sending commands and the Talker drives it when sending data messages Interface Management Lines Five lines are used to manage the flow of information across the interface ATN attention The Controller drives ATN true when it uses the data lines to send commands and false when it allows a Talker to send data messages IFC interface clear The System Controller drives the IFC line to initialize the bus and become CIC REN remote enable The System Controller drives the REN line which is used to place devices in remote or local program mode SRQ service

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