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IOtech Digital488 Manual
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1. 1 6 Introduction 4 80 Digital488 Users Manual 11 28 01 Getting Started 2 Inspection The unit was carefully inspected both mechanically and electrically prior to shipment When you receive the interface carefully unpack all items from the shipping carton and check for any obvious signs of physical damage which may have occurred during shipment Report any such damage found to the shipping agent immediately Remember to retain all shipping materials in the event that shipment back to the factory becomes necessary Every Digital488 is shipped with the following e Digital488 IEEE Digital I O Converter e CN 8 50 Digital I O Port Mating Connector Digital488 User s Manual e Power Supply TR 2 115V or e TR 2E 220V Every Digital488 32 OEM is shipped with the following e Digital488 32 OEM IEEE Digital I O Converter e Digital488 User s Manual e CA 106 1 foot ribbon cable to IEEE488 connector e Macro4880EM 002 Power Plug Assembly Configuration The Digital488 has one internal 8 position switch which determines the unit s IEEE address and its default IEEE bus output terminator The switch is only read when the unit is powered on and should only be set prior to applying power The following figure illustrates the factory default setting for SW1 IEEE Address ra Terminator CR LF EOT Enabled SWI Factory Default Settings To modify any of these defaults follow this simple procedure Dis
2. 2 3 Logic Levels 2 3 Digital I O Port Pin Outs 2 4 Control Lines 2 5 Clear 2 5 Data Strobe 2 5 External Data Ready EDR 2 6 Inhibit 2 6 Trigger 2 6 Service 2 7 IEEE 488 Bus Implementation 2 7 My Talk Address MTA 2 7 My Listen Address MLA 2 8 Device Clear DCL and SDC 2 8 Group Execute Trigger GET 2 8 Interface Clear IFC 2 8 Serial Poll Enable SPE 2 8 serial Poll Disable SPD 2 8 Unlisten UNL 2 8 Untalk UNT 2 8 Installation 2 9 DagBook DagBoard Daq PC Card User s Manual 916895 3 Command Descriptions Bit Set An 3 1 Bit Clear Bn 3 1 Bus Input Output Gn 3 2 Configure Cn 3 2 Data Dn Z 3 3 Data Ready Rn 3 4 End or Identify EOI Execute X 3 5 Format FM 3 5 FO Format ASCII Hexadecimal 3 5 F1 Format ASCII Character 3 6 F2 Format ASCII Binary 3 7 F3 Format ASCII Decimal 3 7 F4 Format Binary 3 8 F5 Format High Speed Binary 3 8 Handshake Hn 3 9 Inhibit Qn 3 9 Invert In 3 9 Port Ph 3 10 Service Request Mask SRQ Mn 3 10 Serial Poll Status Byte 3 11 Status Un 3 12 Terminator Yn 3 14 Test TO 3 15 Index i 4 IEEE 488 Primer History 4 1 General Structure
3. General Description Digital488 The Digital488 32 0EM is a board level interface with the same capabilities as the Digital488 All descriptions in this manual refer to both products unless otherwise stated When the model number Digital488 is used in this manual Digital488 32 OEM is also implied The Digital488 is a digital input and output interface to the IEEE 488 bus Each unit has 40 TTL level digital I O lines which are divided into 5 eight bit ports Each port is software programmable as input or output The Digital488 has several features which give it versatile interface capability A trigger output signal is asserted on the Group Execute Trigger GET command Edge triggered inputs can generate a Service Request on the bus Six data formats are software programmable including ASCII hexadecimal ASCII character ASCII binary binary high speed binary and ASCII decimal There are also individual bit set and bit clear commands Programmable terminators are provided to facilitate interfacing to various controllers A status mode enables the controller to interrogate the programmed status of the Digital488 at any time A self test 1s initiated at power on which checks for proper RAM and ROM operation When addressed to talk the Digital 488 will output data from all forty bits or a selected 8 bit port When addressed to listen the unit will input data and programming information from the controller and output the data to the appropr
4. 19 25 1A 26 1B 27 1C 28 1D 29 1E 30 1F 31 CAN EM SUB ESC FS GS RS US SPE SPD Listen Address Group LAG 20 32 21 33 22 34 23 35 24 36 25 37 26 38 27 39 wee e RR 00 01 02 03 04 05 06 07 29 41 2A 4 2E 46 2F 47 3 A0 28 40 2 2B 43 2C 44 2D 45 08 09 10 11 12 13 14 15 B 1 B 2 Decimal Values 64 to 127 TAG amp SCG 96 Box Items Hexadecimal Value 41 65 Decimal Value A Bus Message 01 in center ASCII Character Talk Address Group TAG 41 65 42 66 43 67 44 68 45 69 Tete 01 02 03 04 05 49 73 4A 7 75 4C 4D 77 I K L M 55 85 T U 2 21 5D 93 l uM 83 54 84 S 0 5C 92 28 61 97 62 98 63 99 64 100 65 101 66 102 7B 123 7D 125 25 26 27 28 29 30 ASCII Code Details Decimal Values 00 to 31 ACG 8 UCG Characteristics ASCII Control Codes Decimal 00 to 31 Dec Hex Character amp Addressed Command Group ACG None NUL Null MEN EN EN EN EN EN IN Note 1 ASCII control codes are sometimes used to formalize a communications session between communication devices 2 DCI DC2 DC3 DC4 FS GS RS and US all have user defined meanings and may vary in use between sessions or devices 3 DC4 is often used as a general stop transmission character 4 Codes used to control cursor position may be used to control print d
5. Digital488 and Digital488 32 0EM IEEE 488 to Digital O Interface IOtech Inc 25971 Cannon Road Cleveland OH 44146 1833 Phone 440 439 4091 Fax 440 439 4093 E mail Product Information sales 1otech com E mail Technical Support productsupport iotech com Internet www iotech com Digital488 and Digital488 32 0EM IEEE488 to Digital O Interface p n 110 0901 Rev 6 0 1990 2004 by lOtech Inc 916895 Printed in the United States of America Warranty Information Your IOtech warranty is as stated on the product warranty card You may contact IOtech by phone fax machine or e mail 1n regard to warranty related issues Phone 440 439 4091 fax 440 439 4093 e mail sales iotech com Limitation of Liability IOtech Inc cannot be held liable for any damages resulting from the use or misuse of this product Copyright Trademark and Licensing Notice All IOtech documentation software and hardware are copyright with all rights reserved No part of this product may be copied reproduced or transmitted by any mechanical photographic electronic or other method without IOtech s prior written consent IOtech product names are trademarked other product names as applicable are trademarks of their respective holders All supplied IOtech software including miscellaneous support files drivers and sample programs may only be used on one installation You may make archival backup copies CE Notice Many IOt
6. F0 ASCII Hexadecimal 4 bits per character F1 ASCII Character 4 bits per character F2 ASCII Binary 1 bit per character F3 ASCII Decimal 8 bits per number F4 Binary each byte represents 8 bits F5 High Speed Binary each byte represents 8 bits FO Format ASCII Hexadecimal In the default F0 format the data is described in ASCII hexadecimal with each character having a value from O thru 9 or A thru F Each ASCII character describes 4 bits of data FO Character Decimal Equiv FO Character Decimal Equiv 0 0 8 8 1 1 9 9 2 2 A 10 3 3 B 11 4 4 C 12 5 5 D 13 6 6 E 14 7 7 F 15 Data received for output to the digital ports must be contained within a prefix D and a suffix Z If the amount of data sent is less than the number of bits programmed as outputs the least significant bits will contain the data sent and the most significant bits will be cleared to logic zero If the data sent is greater than the number of bits programmed for output or selected by the Pn command the Digital488 will generate a conflict error and ignore the entire command string The Data Strobe output is pulse for approximately 50 microseconds after new data 1s output on the selected port s Digital488 User s Manual 7 17 01 Command Descriptions 3 5 When the Digital488 is addressed to talk RO it asserts Inhibit reads the data from all ports unasserts Inhibit and outputs the number of characters determined by the Gn and Pn commands Leading zeros
7. Tips provide advice that may save time during a procedure or help to clarify an issue Tips may include additional reference Specifications and Calibration Specifications are subject to change without notice Significant changes will be addressed in an addendum or revision to the manual As applicable IOtech calibrates its hardware to published specifications Periodic hardware calibration is not covered under the warranty and must be performed by qualified personnel as specified in this manual Improper calibration procedures may void the warranty Quality Notice IOtech has been an ISO 9001 registered firm since 1996 Prior to shipment we thoroughly test our products and review our documentation to assure the highest quality in all aspects In a spirit of continuous improvement IOtech welcomes your suggestions Table of Contents 1 Introduction General Description 1 1 Digital488 1 1 Digital488 32 OEM 1 1 Available Accessories 1 2 Specifications 1 2 Digital488 Specifications 1 2 Digital I O 1 2 IEEE 488 1 3 General 1 3 Digital488 32 OEM Specifications 1 4 Digital I O 1 4 IEEE 488 1 4 General 1 5 Abbreviations 1 6 2 Getting Started Inspection 2 1 Configuration 2 1 IEEE 488 Address Selection 2 2 IEEE 488 Bus Output Terminator Selection 2 3 Digital Input Output Ports
8. 4 7KV2 x 7 SIP 470 x 5 SIP 8 Pole DIP MC68B09P Microprocessor Programmed EPROM 6264 15 8K x 8 CMOS SRAM 65B22 Versatile Interface Adapter Programming Equation 16L8 PAL TMS9914ANL IEEE Controller SN75160BN IEEE Driver SN75162BN IEEE Driver 74LS04 Hex Inverter 68B21 PIA 8 0000 MHz Crystal Service Information 5 7 Notes 5 8 Service Information 916895 Digital488 User s Manual Appendix Command Summary Command Bit Set Bit Clear Bus Output Configure Data Data Ready EOI Execute Format Handshake Inhibit GO Gl G2 CO Cl C2 C3 C4 C5 Dn Z RO R1 KO KI FO Fl F2 F3 F4 F5 HO HI H2 QO Q1 Description Set bit n 1 thru 40 Clear bit n 1 thru 40 Input and Output port data sent on talk Only Input port data sent on talk Only Output port data sent on talk All ports are inputs Port 1 is an output ports 2 thru 5 are inputs Ports 1 and 2 are outputs ports 3 thru 5 are inputs Ports 1 thru 3 are outputs ports 4 and 5 are inputs Ports 1 thru 4 are outputs port 5 is an input All ports are outputs Data to be outputted is entered after D and terminated by Z Data is read when system is addressed to talk Data is latched on EDR transition EOI enabled EOI disabled Execute preceding command string ASCII Hexadecimal ASCII Character ASCII Binary ASCII Decimal Binary High Speed Binary Pulse the Clear line Pulse the Strobe line Pulse the Trigger
9. LAG 32 20 lt space gt Space Bus address 00 ue lt IT oo ENO TC CT T ACT oa pase 5 cc Mi Pes woe pu CU a ue Y NEN PIS Es 5 a NE B p T NE a YY aaa e e Es ET E YY Er EE D TE pres eO PERS T rro LN THEE So ON IT m M MS mo el paw 7 TN TER a E bao TUE T pue Roo nr o eem eN gt o TSE ro YU UNE o o 7 YU ut Rian Cae 48 30 0 Zero Bus address 16 T hls ic 1 NS lo Raso ae bast nho Bin os ru Bus address 0 m ao ae E EN is AA EA EN l c Cia SS en Ja 2 EO RN Ba YU NN O Cc oe M on io hasi ETE VERG GN IH m NE EHE TS an NE TETE cy ban al C a CR om es EE TN IU 0 HN ENE Gueston Mak TES S ww Decimal Values 64 to 95 TAG ASCII Character Set Decimal 64 to 95 Dec Hex Character Name Bus Message Talk Address Group TAG 64 40 At Sign Bus address 00 M ro 2 a GN TE EE r a coe or UU E E E oa ME B EE o ol bars gt D 5 CT O mc p um Les gt i oe ea T NE rs 7 a e can m O ue Ra E um E E NE SEL T bao ros i IC DNE re NM a a o CT RE ES TY bar x FUTT NND c or boat Lo M T Em ee a TT IC el E Pag E x CM m Eo oom nu gt o no a 80 50 P Capital P Sica NE NEUE VESTES T SEEN a VENE NS SENE ON c ESTE ben S ceo e RIT Cas sss u capraru 86 56 V Capital V T s7 ow TER ERN SEE N x SETS baa SEE CON v VETT NS 1 z THE bo leas pe
10. format it asserts Inhibit reads the data from all ports un asserts Inhibit and outputs the binary data to the bus with EOI asserted on the fifth byte When the last data byte is transferred the data is read again in anticipation of another data transfer If Inhibit is used to sequence external hardware this line will pulse N 1 times where N is the number of total 5 byte data transfers In this format the Digital488 does not have to be re addressed to talk to read the ports multiple times With all Fn formats using the Digital488 the data is output in a PORTS PORTA PORT3 PORT2 PORT 1 sequence Using the Digital488 32 OEM the data is output in a PORT4 PORT3 PORT2 PORT1 sequence Digital488 User s Manual 11 19 01 Getting Started 2 7 My Listen Address MLA When the Digital488 is addressed to listen in the F0 through F4 format it accepts characters from the active talker and interprets these characters as commands and command parameters These commands are explained in Chapter 3 In the high speed binary format F5 the command interpreter is disabled The Digital488 treats all bytes received as data to be output to the Digital I O ports Each time it receives five bytes or detects EOI it pulses the Data Strobe for approximately 15 microseconds Using the Digital488 data is expected I n a PORTS PORTA PORT3 PORT2 PORTI sequence Using the Digital488 32 OEM data is expected in a PORT4 PORT3 PORT2 PORTI sequence If only t
11. s D io o a o t O a O O O O io a E EB a O O ol O O Y O o aj o aj o D el o o O o Digital488 User s Manual 916895 Service Information 5 5 Digital488 0EM Component Layout doddaI Das N31sIi7 IVL H3MoOd NO OQ OO W 9010 solad rola 010 010 WOddaI Twd48191 GINNVHIO AA uonenb3 weibold 009 88t 1VLIDIC kO9 88FTY1L191O MOSS3203dOMOIIN WYNS SONO d608892 8 X N8 iin LOLN on HILHIANI HINO X3H 3331 60LN om YATIONLNOD 333 YIAN O 333 O POL 25 x 2 Header 12 x 2 Header 43ILAVOY 39V3431NI JULVSHAA 22959 90LN BOLN IEEE 488 Connector Digital488 User s Manual 916895 5 6 Service Information Digital488 OEM Replaceable Parts Schematic C101 C112 C113 C114 C115 C116 D101 D102 D106 J101 J102 J103 J104 R101 R102 R103 S101 U101 U102 U103 U104 U105 U106 U107 U108 U109 U110 U112 Y101 Digital488 User s Manual Part Number C 5 1 C 5 1 C 5 15p C 2 10 RF 1 DD 2 CN 2 CN 5 12 CN 5 25 CN 32 2 R 1 68K RN 4 4 7K RN 2 470 SW 6 8 IC 1 Digital488 600 IC 41 IC 23 Digital488 601 IC 3 IC 4 IC 5 IC 33 IC 2 CR 5 916895 Description Ceramic 25v Ceramic 25v Ceramic 25v Electrolytic 25v Small Signal Diode Red PC Mount IEEE 488 Connector 12 x 2 0 1 Header 25 x 2 0 1 Header 2 position Mate N Loc Socket 68K 1 4w carbon
12. the ability to control 09 Secondary Command Group SCG These are any one of the 32 possible commands 0 to 31 in this group They must immediately follow a talk or listen address 60 to 7F Digital488 User s Manual 11 20 01 IEEE488 Primer 4 5 Parallel Poll Configure PPC This configures devices capable of performing a Parallel Poll as to which data bit they are to assert im response to a Parallel Poll 05 Parallel Poll Unconfigure PPU This disables all devices from responding to a Parallel Poll 15 More On Service Requests Serial Poll Parallel Poll Most of the commands covered both uniline and multiline are the responsibility of the Active Controller to send and the bus devices to recognize Most of these happen routinely by the interface and are totally transparent to the system programmer Other commands are used directly by the user to provide optimum system control Of the uniline commands SRQ 1s very important to the test system and the software designer has easy access to this line by most devices Service Request is the method by which a bus device can signal to the Controller that an event has occurred It is similar to an interrupt in a microprocessor based system Most intelligent bus peripherals have the ability to assert SRQ A DMM might assert it when its measurement is complete if its input 1s overloaded or for any of an assortment of reasons A power supply might SRQ if its output has cur
13. 0 3 to 7 0 volts All I O lines are referenced to COMMON Pin 50 Digital488 User s Manual 11 19 01 Getting Started 2 3 Digital I O Port Pin Outs The following diagram illustrates the digital I O edge connector as view from the rear of the Digital488 and the top PC Board edge view of the Digital488 32 0EM Inhibit O External Data Ready I Not Used External Data Ready sn GND Inhibit O om Gh Trigger al Data Strobe 2 10 Dana ko p Bits 1 thru 40 T e 39 l i PC Board Edge 5 Volts Clear O L 5 Volts 1 Input Service I 50 mA Max D Input Trigger O 50 mA Max O Output Data Strobe O O Output Service D Not Used Digital488 Rear Panel I O Connector Pin Out Digital488 32 0EM I O Connector Pin Out Digital488 Digital488 32 0EM thru 8 DATA PORT Input or Output thru 8 Least Significant Port Pin 1 is bit 1 LSB Pin 8 1s bit 8 MSB Least Significant Port DATA PORT2 Input or Output thru 16 9 thru 16 ida Pin 9 is bit 1 LSB Pin 16 is bit 8 MSB E DATA PORT3 Input or Output Pin 25 is bit 1 LSB Pin 32 is bit 8 MSB Most Significant Port 33 thru o PATA POR Ta Input or put Musas EE NA MO uu E 5 Volts Do not exceed 50 mA Toad O COMMON Gnd 2 4 Getting Started 11 19 01 Digital488 User s Manual Control Lines Six control lines enable handshaking of digital I O data transfer to the Digital488 They are automatically acti
14. Bit Set command The bit which is being set must have been configured as an output bit by the Configure command to be valid The Strobe output line is not pulsed when the Bit Set command is sent An Bitn 1 thru 40 is set to logic one Example CLEAR 718 reset the Digital488 OUTPUT disc configure all ports as output OUTPUT 718 A22x set bit 22 to a logic one OUTPUT 718 A23XA24xX set bits 23 and 24 to a logic one Bit Clear Bn The Bit Clear command will clear to a logic zero an output bit described by the argument n Clearing a bit may represent either a O volt or 5 volt output depending on whether an Invert command 116 has been sent If data is active high default condition then Bit Clear outputs O volts When multiple Bit Clear commands are used in the same command string an Execute command X must follow each command The bit that is being cleared must have been defined as an output by the Configure command in order to be valid The Strobe output line is not pulsed when the Bit Clear command is sent Bn Bitn 1 thru 40 is cleared to a logic O Example CLEAR 718 reset the Digital488 OUTPUT 416x C5x configure all ports as output OUTPUT 718 A7XA8XA9X set bits 7 8 and 9 to 5 volts OUIBUT Tl5s 5g9JS clear bit 7 to zero volts OUTPUT 718 B8XB9X clear bits 8 and 9 to zero volts Digital488 User s Manual 7 17 01 Command Descriptions 3 1 Bus Input Output Gn The Bus Output command determines
15. SRQ modes will remain enabled until the M0 command is sent or the controller sends a Device Clear DCL Selected Device Clear SDC or Interface Clear IFC command MO SRQ is disabled M1 SRQ on Service input transition M2 SRQ on EDR input transition M4 SRQ on bus error M8 SRQ on Self Test error M16 SRQ on Ready MO default mode disables the SRQ function preventing the Digital488 from generating a Service Request M1 will generate a Service Request when the Service Input line makes a transition Refer to the Invert command 164 description for programming the polarity of the Service input line M2 will generate a Service Request when the EDR input makes a transition Refer to the Invert command 132 description for programming the polarity of the EDR input line M4 will generate a Service Request when a bus error occurs The most common bus error is sending an invalid command to the Digital488 For example attempting to select an F6 format when no F6 format exists will generate a Service Request when the M4 mode is selected 3 10 Command Descriptions 7 17 01 Digital488 User s Manual MS will generate a Service Request when the Digital488 self test fails Refer to the Test command TO description for details on self tests M16 will generate a Service Request when the Digital488 has completed the execution of a set of commands from the bus controller This is used by the controller to assure the completion of a set of commands
16. a mE a a Backward Slash E TOE peo a ka icc cae 95 5F Underscore Untalk UNT Decimal Values 96 to 127 SCG ASCII Character Set 96 to 127 Dec Hex Character Name BusMessage Secondary Command Group SCG 96 60 Grave o He PES Nu Lowercase A ie c3 1 Lowercase B SONIS Lowercase c m SEEN a LosenasD ee IDEE NW Lowercase E hay O Lowercase E a aaa oe T SUN Rn Lowercase H ne SEES el Lowercase TUNE a HN ea 67 C35 e Lonenask le SEE E i LonecasL M NONE EE m Lowercase M E a Lowercase N EN ZEE E o iguscaco 112 70 p Lowercase P E aa mes com eeu hist Wl ur tonercase a M MR Lowercase S A rn Ka meee Lowercase U a EE ONE Lonenasev ZEE SN Lowercase W Em DUE NE Lowercase X ra a M HN LOUER ARS EXE Lowercase bat ca E 0 Ci fan ace Vertical Line la Cay Ca Em eTA nu 127 7F DEL Delete Command 31 Notes Appendix Digital488 0EM Mechanical Dimensions AIND JO PD A c a HHA DHS N31511 Te L HAMOG LA AIMD3 JO p g 5 0 Z1 MS La J31HVS g S 0 G2 1 MS Le IILkNS 0S 2 ve cia W Wu w SF 00 c 511 SSz div p S600 PN for ss 0065 OE MEN sadejd p ela 9910 Mounting Holes Board Dimensions Note Does not imply ortentation IEEE Connector Mounting and Hole Punch Out
17. before sending a subsequent set of commands Example CLEAR 718 reset the Digital488 OUTPUT 718 MAX select SRQ on Bus error OUTPUT 718 TE7X send an invalid bus command Note ERROR and SRQ LEDs should illuminate CLEAR 718 reset the Digital488 OUTPUT 718 MIXM4X select SRQ on Bus error and SRQ on Service input OUTPUT 718x MaX This has the same effect as the command above where M1X plus M4X equals M5X Serial Poll Status Byte The Serial Poll Output byte is sent upon receiving the serial poll command from the controller Refer to the SRQ description for details on how the Serial Poll byte is affected Below is a description of the significance of each bit in the Serial Poll byte Bit Location DIO1 LSB DIO2 DIO3 DIO4 DIO5 DIO6 DIO7 DIO8 MSB Significance SRQ Bit Value if set to logic 1 1 Service Input transition 2 EDR input transition 4 Bus error 8 Test error 16 Ready for more commands 32 not assigned always O 64 Service Request bit 128 not assigned always O Serial Poll Bit Description DIO1 DIO2 DIO3 DIO4 Digital488 User s Manual When enabled by the M1 command DIO1 is set by a transition on the Service Input line active transition state determined by the Invert command 164 DIO1 is cleared after the controller serial polls the Digital488 When enabled by the M2 command DIO2 is set on an EDR transition active transition state determined by the Invert command 132 DIO2 is clear
18. line Clear Inhibit line Set Inhibit line Command Invert Port SRQ Mask Status Terminator Test Code 10 Il D 14 I8 116 132 164 PO P1 P2 P3 P4 PS MO MI M2 M4 M8 M16 UO YO Y1 Y2 Y3 TO Description All control line outputs are active high Inhibit output is active low Trigger output is active low Data Strobe output is active low Clear output is active low Data is low true EDR input is falling edge sensitive Service input is falling edge sensitive All ports selected Port 1 selected Port 2 selected Port 3 selected Port 4 selected Port 5 selected SRQ is disabled SRQ on Service Input transition SRQ on EDR input transition SRQ on Bus error SRQ on Self test error SRQ on Ready Send Status information when next addressed to talk CHE FHG IHHKAM H HPHR Y Read state of bit n 1 thru 40 CR LF LF CR CR only LF only Perform RAM and ROM test Appendix B ASCII Code Summary Decimal Values 00 to 63 ACG UCG amp LAG Box Items Hexadecimal Value 41 65 Decimal Value A Bus Message 01 in center ASCII Character Addressed Command Group ACG 00 00 01 01 02 02 03 03 04 04 05 05 06 06 07 07 NUL SOH STX ETX EOT ENQ ACK BEL Cm e im e o e 08 08 09 09 SOA 10 SOB 11 0E 14 SOF 15 OA GET TCT 10 16 11 17 12 18 13 19 14 20 15 21 16 22 17 23 DLE DC1 DC2 DC3 DC4 NAK SYN ETB LLO DCL PPU 18 24
19. when they are ready for more data This assures that all devices that are to accept the information are ready to receive it Not Data Accepted NDAC The NDAC line is also controlled by the Listeners This line indicates to the Talker that each device addressed to listen has accepted the information Each device releases NDAC high at its own rate but the NDAC will not go high until the slowest Listener has accepted the data byte ist Data Byte 2nd Data Byte lar WM DIO1 B composite MAGIA A Le Ys RE DAV Valid Not Valid Not POL Valid Valid NRED All None All None Acceptor 1 Ready Read Ready Read NDAC None All None All Acceptor Accept Accept Accept Accepl IEEE Bus Handshaking Data Lines The GPIB provides eight data lines for a bit parallel byte serial data transfer These eight data lines use the convention of DIO1 through DIOS instead of the binary designation of DO to D7 The data lines are bi directional and are active low 4 4 IEEE 488 Primer 20 Digital488 Users Manual Multiline Commands Multiline bus commands are sent by the Active Controller over the data bus with ATN asserted These commands include addressing commands for talk listen Untalk and Unlisten Go To Local GTL This command allows the selected devices to be manually controlled 01 Listen Address Group LAG There are 31 O to 30 listen addresses associated with this group The 3 most significant bits of the data bus ar
20. with the Data Ready command R1 The EDR signal must be at least 1 microsecond wide and must have a rise and fall time of less than one microsecond The EDR line is normally rising edge sensitive but can be programmed with the Invert command 132 to be falling edge sensitive Refer to the following diagram for timing relationships When using the EDR line with the R1 command data is not read when the Digital488 is addressed to talk as with RO The Digital488 will only output data when the EDR line transitions EDR is not functional in the high speed binary F5 format Inhibit Digital488 Pin 44 Digital488 32 OEM Pin38 The Inhibit output is asserted while data on the selected I O port is being read into the I O port buffer This line is normally active high but may be programmed active low by the Invert command 11 The Inhibit line can be programmed independent of any I O operations with the Inhibit command Qn Refer to the following diagram for timing relationships The Inhibit line is asserted once for each data read operation for all format Fn modes except high speed binary FS In this mode it is asserted for the first data read after the Digital488 is addressed to talk On the last data byte transfer the data is read again with Inhibit asserted in anticipation of another data transfer If Inhibit is used to sequence external hardware you should be aware that this line will pulse N 1 times where N is the number of total 5 b
21. 01 Digital488 User s Manual The status returned after receiving a UI through U40 is an ASCII character 1 or 0 depending on the level of the line and the state of the Invert command 116 CLEAR 718 reset the Digital488 OUTPUT Jee 22 request the status of bit 22 ENTER 718 AS read the status bit DISP AS display shows a 0 dependent on the signal applied to the input Below is a summary of the Status UO information C Configuration CO All ports are inputs C1 Port 1 is an output ports 2 thru 5 are inputs C2 Ports 1 and 2 are outputs ports 3 thru 5 are inputs C3 Ports 1 thru 3 are outputs ports 4 and 5 are inputs C4 Ports 1 thru 4 are outputs port 5 is an input C5 All ports are outputs EF Error Message 0 No error 1 Unrecognized command ex W3 2 Illegal command option ex F8 3 Conflict attempt to output data to an input port 4 ROM error 5 RAM error F Data Format F0 Hexadecimal F1 ASCII F2 Binary F3 Decimal F4 High Speed Binary IH Invert Control Lines 10 All control and data lines are active high I1 Inhibit output is active low I2 Trigger output is active low I4 Data Strobe output is active low I8 Clear output is active low 116 Data is active low 132 EDR input is falling edge sensitive 164 Service input is falling edge sensitive Note the status indication reflects the sum of all received Invert commands Digital488 User s Manual 7 17 01 Command Descriptions 3 13 K End Or Ident
22. 1 IC 33 IC 30 IC 1 CR 5 916895 Description Ceramic 25v Ceramic 25v Ceramic 25v Flectrolytic 25v Ceramic 25v Small Signal Diode Red PC Mount IEEE 488 Connector 68K 1 4w carbon 4 7K x 7 SIP 470 x 5 SIP 3942 1w carbon Programmed EPROM 6264 15 8K x 8 CMOS SRAM 65B22 Versatile Interface Adapter TMS9914ANL IEEE Controller SN75160BN IEEE Driver SN75162BN IEEE Driver Programming Equation 16L8 PAL 74LS04 Hex Inverter LM7805CT Regulator 5v MC68BO9P Microprocessor 8 0000 MHz Crystal Service Information 5 3 Digital488 I O Board Component Layout and Schematic Replaceable Parts C201 C205 C123 R201 R202 R206 S201 U201 U202 U204 U205 U206 CN 4 4 50F VO00000000000C000 06000000000000000 800400000000000D50 5 4 Service Information 916895 Part Number C 5 1 C 5 1 R 1 1K R 1 1K SW 6 8 IC 1 IC 2 IC 47 IC 32 EFEBE29F SOCKET 5 1 49 THLE IC 2 EF BAEZ AP SOCKET 50 1 40 UZD4 IC 3 EFEBBZ1P SOCKET S0 1 40 J2D3 Description Ceramic 25v Ceramic 25v IK 1 4w carbon IK 1 4w carbon 8 Pole DIP MC68B09P Microprocessor 68B21 PIA 74LS05 74LS375 Digital488 User s Manual Digital488 32 0EM Component Layout 0 156 DIA 4 PLACES ULATED 5 VDC 1A LED i E TALK SD SRO E D error US EJ ES LI LA LJ dl Bl z 3 750 a Di a cm um IA 1 365 TI O00000000000f CB Fire aul
23. 4 1 Send It To My Address 4 3 Bus Management Lines 4 3 Attention ATN 4 3 Interface Clear IFC 4 3 Remote Enable REN 4 3 End or Identify EOI 4 3 Service Request SRQ 4 3 Handshake Lines 4 4 Data Valid DAV 4 4 Not Ready for Data NRFD 4 4 Not Data Accepted NDAC 4 4 Data Lines 4 4 Multiline Commands 4 5 Go To Local GTL 4 5 Listen Address Group LAG 4 5 Unlisten UNL 4 5 Talk Address Group TAG 4 5 Untalk UNT 4 5 Local Lockout LLO 4 5 Device Clear DCL 4 5 Selected Device Clear SDC 4 5 serial Poll Disable SPD 4 5 Serial Poll Enable SPE 4 5 Group Execute Trigger GET 4 5 Take Control TCT 4 5 Secondary Command Group SCG 4 5 Parallel Poll Configure PPC 4 6 Parallel Poll Unconfigure PPU 4 6 More On Service Requests 4 6 Serial Poll 4 6 Parallel Poll 4 6 5 Service Information Factory Service 5 1 Theory of Operation 5 1 Digital488 Mother Board 5 2 Digital488 I O Board 5 4 Digital488 32 OEM 5 5 Digital488 OEM 5 6 Appendix A Digital488 Command Summary Appendix B IEEE Command and Address Messages Appendix C Digital488 0EM Mechanical Dimensions li 916895 DBK Option Cards amp Modules User s Manual Introduction 1
24. Do not use this interface outdoors The interface is intended for indoor use only Outdoor conditions could result in equipment failure bodily injury or death CAUTION Never disassemble the interface case while it is connected to the AC power line Internal voltage potentials exist which could cause bodily injury or death Digital O Configuration Four 8 bit ports programmable as inputs or outputs Transistor Transistor Logic TTL Levels Outputs will drive 2 TTL loads Connector One 40 pin header organized as two rows of 20 pins IEEE 488 Implementation SH1 AH1 T6 TEO L4 LEO SR1 RLO PPO DC1 DT1 CO E1 Terminators Selectable CR LF LF CR and CR LF with EOI Programmable IEEE Terminators EOI SRQ Mask Port Data Active Levels Handshake Lines Format and Configuration Connector Standard IEEE 488 connector with metric studs General Configuration Four 8 bit ports programmable as inputs or outputs Also included are programmable handshake lines data latching capability Clear and Trigger outputs and a Service Request SRQ input Dimensions 101 6mm square x 16 51mm high 4 square x 0 65 high Weight 0 13 kg 0 29 Ibs Operating Environment Standard Indoor 0 to 50 C 0 to 70 RH to 35 C Linearly derate 3 RH C from 35 to 50 C Controls IEEE parameter switches Indicators On board and 10 pin header for remote use The external LEDs are connected to VCC through a resis
25. Poll Unconfigure PPU Take Control TCT Parallel Poll Disable PPD My Talk Address MTA When the Digital488 is addressed to talk RO it asserts Inhibit reads the data from all ports un asserts Inhibit and outputs the data to the bus in the format as defined by the Fn Pn and Gn commands The output bus terminators are appended to the output with the exception of the F4 and F5 formats F4 does not append terminators The output format of F5 will be described separately After output in the FO through F4 formats the Digital488 must be re addressed to talk to perform subsequent reads In the R1 mode it will wait for the selected EDR transition before reading the data and formatting it for output If the EDR line has transitioned prior to being addressed to talk the data read at the time of EDR will be buffered for output when next addressed to talk If EDR transitions again before the previous EDR buffered data has been output the Digital488 will generate an EDR Overrun error and ignore the EDR read request After output in the FO through F4 formats the Digital488 must be re addressed to talk to perform subsequent buffered output of EDR captured data In either Rn mode the Digital488 can send requested status Un without affecting the data ports or Inhibit After the requested status is output the presently programmed Rn mode returns EDR cannot be used to capture data in the high speed binary format F5 When addressed to talk in this
26. RO it asserts Inhibit reads the data from all ports unasserts Inhibit and outputs the number of characters determined by the Gn and Pn commands Leading zeros are not suppressed and the bus terminators are appended to the output After output the Digital488 must be re addressed to talk to perform subsequent reads EDR R1 may also be used to capture data in this format Example OUTPUT 1182 EILX select ASCII Character format ENTER 718 AS read data from the Digital488 DISP AS display shows 456 OUTPUT TIG DI ADS send 1222 to the Digital488 ENTER 718 AS read data from the Digital488 DISP AS display shows 1 2 3 6 Command Descriptions 7 17 01 Digital488 User s Manual F2 Format ASCII Binary In the F2 format the each data bit is described with an ASCII O or 1 Each byte is formatted in two 4 bit multiples separated by semicolons F2 String Decimal Equiv F2 String Decimal Equiv 0000 0000 0 000051001 9 0000 0001 1 0000 1010 10 0000 0010 2 0000 1011 11 0000 0011 3 0000 1100 12 0000 0100 4 0000 1101 13 0000 0101 5 0000 1110 14 0000 0110 6 0000 1111 15 0000 0111 7 1000 0001 129 0000 1000 8 1111 1111 255 Data received for output to the digital ports must be contained within a prefix D and a suffix Z and each 4 bit quantity must be separated by semicolons Leading zeros are not required If the amount of data sent is less than the number of bits programmed as outputs the least significant bits will contain the data sent and t
27. a received for output to the digital ports must be contained within a prefix D and a suffix Z If the amount of data sent is less than the number of bits programmed as outputs the least significant bits will contain the data sent and the most significant bits will be cleared to logic zero If the data sent is greater than the number of bits programmed for output or selected by the Pn command the Digital488 will generate a conflict error and ignore the entire command string The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the selected port s When the Digital488 is addressed to talk RO it asserts Inhibit reads the data from all ports unasserts Inhibit and outputs the number of characters determined by the Gn and Pn commands Leading zeros are not suppressed and the bus terminators are appended to the output After output the Digital488 must be re addressed to talk to perform subsequent reads EDR R1 may also be used to capture data in this format Example OUTPUT 7107 rox select decimal mode ENTER 718 AS read data from the Digital488 DISP AS display shows 240 165 OUTPUT 718 DL00 2002X output 100 amp 200 to the Digital488 ENTER 718 AS read data from the Digital488 DISP AS display shows 100 200 F4 Format Binary In the F4 binary format no error checking is performed and caution must be exercised when using this mode to avoid locking the IEEE bus When addressed to listen the Dig
28. allel Poll by simultaneously asserting EOI and ATN Service Request SRQ When a device desires the immediate attention of the Active Controller it asserts SRQ It is then the Controller s responsibility to determine which device requested service This is accomplished with a Serial Poll or a Parallel Poll Digital488 User s Manual 11 20 01 IEEE488 Primer 4 3 Handshake Lines The GPIB uses three handshake lines in an I m ready Here s the data I ve got it sequence This handshake protocol assures reliable data transfer at the rate determined by the slowest Listener One line is controlled by the Talker while the other two are shared by all Active Listeners The handshake lines like the other IEEE 488 lines are active low Data Valid DAV The DAV line is controlled by the Talker The Talker verifies that NDAC is asserted active low which indicates that all Listeners have accepted the previous data byte transferred The Talker then outputs data on the bus and waits until NRFD is unasserted high which indicates that all Addressed Listeners are ready to accept the information When NRFD and NDAC are in the proper state the Talker asserts DAV active low to indicate that the data on the bus 1s valid Not Ready for Data NRFD This line is used by the Listeners to inform the Talker when they are ready to accept new data The Talker must wait for each Listener to unassert the line high which they will do at their own rate
29. and Listen Device 3 Printer Only Able to Listen Device 4 Frequency Counter Only Able to Talk IEEE 488 Bus Structure 11 20 01 Designate all the devices that are to listen by addressing those devices to listen Indicate to all devices that the data transfer can take place Data Bus Data Byte Transfer Control General Interface Management pio DAV NRFD NDAC IFC ATN SRQ REN IX Digital488 User s Manual Send It To My Address In the previous discussion the terms Addressed to Talk and Addressed to Listen were used These terms require some clarification The IEEE 488 standard permits up to 15 devices to be configured within one system Each of these devices must have a unique address to avoid confusion In a similar fashion every building in town has a unique address to prevent one home from receiving another home s mail Exactly how each device s address is set is specific to the product s manufacturer Some are set by DIP switches in hardware others by software Consult the manufacturer s instructions to determine how to set the address Addresses are sent with universal multiline commands from the Active Controller These commands include My Listen Address MLA My Talk Address MTA Talk Address Group TAG and Listen Address Group LAG Bus Management Lines Five hardware lines on the GPIB are used for bus management Signals on these lines are often referred t
30. are not suppressed and the bus terminators are appended to the output After output the Digital488 must be re addressed to talk to perform subsequent reads EDR R1 may also be used to capture data in this format Example DIM AS 50 dimension the length of A CLEAR 718 reset the Digital488 OUTPUT 718 C2G2x configure ports 1 amp 2 as output OUTPUT 718 D4E6BZX output hexadecimal 4E6B to ports 1 amp 2 ENTER 718 AS read data from the Digital488 DISP AS display shows 4E6B F1 Format ASCII Character In the F1 format the data is coded and transmitted in ASCII Characters with the four least significant bits of each ASCII character representing four bits of data F1 Character Decimal Equiv F1 Character Decimal Equiv 0 0 8 8 1 1 9 9 2 2 10 3 3 11 4 4 lt 12 5 5 13 6 6 gt 14 9 7 15 Data received for output to the digital ports must be contained within a prefix D and a suffix Z If the amount of data sent is less than the number of bits programmed as outputs the least significant bits will contain the data sent and the most significant bits will be cleared to logic zero If the data sent is greater than the number of bits programmed for output or selected by the Pn command the Digital488 will generate a conflict error and ignore the entire command string The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the selected port s When the Digital488 is addressed to talk
31. connect the power supply from the AC line and from the interface Disconnect any IEEE or digital I O cables prior to disassembly Digital488 User s Manual 11 19 01 Getting Started 2 1 WARNING Never open the Digital488 case while it is connected to the AC line Failure to JIN observe the warning may result in equipment failure personal injury or death Remove the four screws located in each corner of the rear panel Hold the case firmly and pull the rear panel outward noting the slot location of the main circuit board Modify those parameters which are appropriate for your installation and reassemble the unit Slide the main circuit board into the previously noted slot and finish reassembly by tightening the four screws into the rear panel IEEE 488 Address Selection The IEEE 488 bus address is set by SW 1 1 through SW 1 5 The address can be set from O through 30 and is read only at power on The address is selected by simple binary weighting with SW1 1 being the least significant bit and SW 1 5 the most significant bit The factory default is address 18 If address 31 is selected it defaults to address 30 because the IEEE 488 standard has reserved address 31 DOCE OPEN 1x16 16 0x8 0 0x4 0 1x2 2 Ux 0 IEEE Address 18 SWI View for IEEE Bus Address Selection 2 2 Getting Started 11 19 01 Digital488 User s Manual IEEE 488 Bus Output Terminator Selection The terminating characters sent on output by the Dig
32. d such as carriage return or line feed will be considered data and the output ports will reflect those character values When addressed to talk in this format it asserts Inhibit reads the data from all ports unasserts Inhibit and outputs the binary data to the bus with EOI asserted on the fifth byte When the last data byte is transferred the data is read again in anticipation of another data transfer If Inhibit is used to sequence external hardware this line will pulse N 1 times where N is the number of total 5 byte data transfers In this format the Digital488 does not have to be re addressed to talk to read the ports multiple times EDR cannot be used to capture data in the F5 high speed binary format The only programmable method to exit the F5 high speed binary format is device clear DCL or Selected Device Clear SDC When received it enables the command interpreter and changes the format to FO All other parameters remain unchanged In addition the Clear output line is not pulsed by DCL or SDC when the interface is in FS 3 8 Command Descriptions 7 17 01 Digital488 User s Manual Handshake Hn The Handshake control command enables software control of the handshake lines independent of any other I O operations When the Digital488 receives a Hn command the respective handshake line is pulsed for approximately 50 microseconds It returns to its steady state condition after pulsing The Invert command may be used to chan
33. e error is repeatable If the LEDs do not flash and the POWER indicator does not remain lit there may not be any power supplied to the interface In this event check to make sure the AC power is supplied to the power supply and that the supply 1s properly installed into the unit If the problem 1s unresolved refer to the Service Information section of this manual Digital488 User s Manual 11 19 01 Getting Started 2 9 2 10 Getting Started 11 19 01 Digital488 User s Manual Command Descriptions 3 Control of the Digital 488 is implemented with 17 bus commands described here in detail Examples are given for many of the commands using a Hewlett Packard 85 computer in the immediate mode It is implied that each command is terminated by the END LINE key on the HP 85 in order to execute the command The Digital488 bus address should be set to 18 for all examples It is necessary that the EXECUTE command X follow all command strings sent to the Digital488 No commands are executed until an X is received by the Digital488 Bit Set An The Bit Set command programs a logic one output to a bit described by the argument n Setting a bit may represent either a 5 volt or O volt output depending on whether an Invert command 116 has been sent If data is active high default condition then Bit Set outputs 5 volts If multiple bits are to be set within the same command string an Execute command X must be included after every
34. e set to 001 while the 5 least significant bits are the address of the device being told to listen Unlisten UNL This command tells all bus devices to Unlisten The same as Unaddressed to Listen 3F Talk Address Group TAG There are 31 O to 30 talk addresses associated with this group The 3 most significant bits of the data bus are set to 010 while the 5 least significant bits are the address of the device being told to talk Untalk UNT This command tells bus devices to Untalk The same as Unaddressed to Talk 5F Local Lockout LLO Issuing the LLO command prevents manual control of the instrument s functions 11 Device Clear DCL This command causes all bus devices to be initialized to a pre defined or power up state 14 Selected Device Clear SDC This causes a single device to be initialized to a pre defined or power up state 04 Serial Poll Disable SPD The SPD command disables all devices from sending their Serial Poll status byte 19 Serial Poll Enable SPE A device which is Addressed to Talk will output its Serial Poll status byte after SPE is sent and ATN is unasserted 18 Group Execute Trigger GET This command usually signals a group of devices to begin executing a triggered action This allows actions of different devices to begin simultaneously 08 Take Control TCT This command passes bus control responsibilities from the current Controller to another device which has
35. ech products carry the CE marker indicating they comply with the safety and emissions standards of the European Community As applicable we ship these products with a Declaration of Conformity stating which specifications and operating conditions apply Warnings Cautions Notes and Tips m Refer all service to qualified personnel This caution symbol warns of possible personal injury or equipment damage under noted conditions Follow all safety standards of professional practice and the recommendations in this manual Using this equipment in ways other than described in this manual can present serious safety hazards or cause equipment damage This warning symbol is used in this manual or on the equipment to warn of possible injury or death from electrical shock under noted conditions This ESD caution symbol urges proper handling of equipment or components sensitive to damage from electrostatic discharge Proper handling guidelines include the use of grounded anti static mats and wrist straps ESD protective bags and cartons and related procedures This symbol indicates the message is important but is not of a Warning or Caution category These notes can be of great benefit to the user and should be read In this manual the book symbol always precedes the words Reference Note This type of note identifies the location of additional information that may prove helpful References may be made to other chapters or other documentation
36. ector with metric studs General Configuration Five 8 bit ports programmable as inputs or outputs Also included are programmable handshake lines data latching capability Clear and Trigger outputs and a Service Request SRQ input Terminal Installation Category Standard Not Applicable CE Category 1 for all terminals Dimensions 188 mm deep x 140 mm wide x 68 mm high 7 39 x 5 5 x 2 68 Weight 1 55 kg 3 6 lbs Operating Environment Standard Indoor 0 to 50 C 0 to 70 RH to 35 C Linearly derate 3 RH C from 35 to 50 C CE Indoor use at altitudes below 2000 meters 0 to 40 C 80 maximum RH up to 31 C decreasing linearly 4 RH C to 40 C Controls Power switch external and IEEE parameter switches internal Indicators LED indicators for IEEE TALK LISTEN SRQ ERROR and POWER Power An external power supply is provided with the Digital488 Input is 105 125 VAC or 210 250 VAC 50 60 Hz 10 VA maximum The external power supply 9 VDC output is to be connected to the Digital488 power input marked 10 VDC MAX 500 mA WARNING Do not use this interface outdoors The interface is intended for indoor use only Outdoor conditions could result in equipment failure bodily injury or death CAUTION Do not connect AC power line directly to the Digital488 Direct AC connection will damage equipment Digital488 User s Manual 11 28 01 Introduction 1 3 Digital488 32 0EM Specifications WARNING
37. ed after the controller serial polls the Digital488 DIOB is set when an invalid command is sent to the Digital488 The M4 command will enable a Service Request to occur then an invalid command is received The bit is cleared after the controller sends a Status command U0X and reads the status string from the Digital488 The status of DIO4 is determined after the Test command TOX is sent to the Digital488 If the self test passes the DIO4 bit will remain a zero If the self test fails DIO4 will be set to a logic 1 The M8 command will cause a Service Request to be generated in addition to DIO4 being set if the self test fails The DIO4 bit is cleared after the controller sends a Status command UOX and reads the status string from the Digital488 7 17 01 Command Descriptions 3 11 DIOS The DIOS bit is set after an entire command string has been received and processed by the Digital488 The bit is clear while the Digital488 is processing commands that have been received from the controller When used with the M16 command a Service Request will also be generated when the DIOS bit is set An Execute command X must be received before the DIOS bit can be cleared DIO6 DIO6 is not used and is always a logic zero DIO7 When the Digital488 generates a Service Request the DIO7 will be set to a logic one This is used by the controller to determine that the Service Request was generated by the Digital488 DIO8 DIOS is not used and is al
38. egulated 9 volt wall mount supply Regulation to the required 5 volts 1s provided by U109 7805 Decoding of the microprocessor address space 1s accomplished with a Programmable Logic Array U110 16L8 The Memory space allocation is Address Device Part Number Function 6000 7FFF U103 6264 Static RAM 9200 9204 U202 6821 Digital I O 9400 9404 U203 6821 Digital I O 9800 9804 U204 6821 Digital I O A000 A007 U106 TMS9914A IEEE Controller B000 BO0F U104 R65C22 VIA E000 FFFF U102 2764 Programmed EPROM Digital488 User s Manual 916895 Service Information 5 1 Digital488 Mother Board Component Layout c Qd Qaa c Qd z ga 00 ki POLA e010 Do E 50 1 40 KA Sh 74Ls04 n 10 33 L 44 LOLO LOLA 2789 1 4 ELLS FOLS S0 1 28 ESTO JOG D Sc w2 JO y OLLO Digital488 600 IG 40 W101 S0 1 40 2 10 4 47 K 0 9914 C 3 S o c SO 1 40 5 OO no 75160A 75162A U107 Q e 108 LOLP 5 2 Service Information 916895 Digital488 User s Manual Digital488 Motherboard Replaceable Parts Schematic C101 C108 C110 C113 C117 C118 C124 C123 D101 D102 D106 J101 R101 R102 R104 R105 U102 U103 U104 U106 U107 U108 U110 U113 U109 201 Y101 Digital488 User s Manual Part Number C 5 1 C 5 1 C 5 15p C 2 10 C 5 1 RF 1 DD 2 CN 2 R 1 68K RN 4 4 7K RN 2 470 R 2 39 Digital488 600 IC 41 IC 23 IC 3 IC 4 IC 5 Digital488 60
39. es the default EOI mode The controller can change the EOI mode by programming the Digital488 from the bus In the KO mode the EOI line is asserted by the Digital488 on the last byte of every bus output string In the K1 mode the EOI function is disabled except when using the binary modes F4 and F5 KO EOI enabled assert EOI on last byte transferred KI EOI disabled do not assert EOI on last byte transferred Example OUTPUT TLE ELX disables EOI on last byte 3 4 Command Descriptions 7 17 01 Digital488 User s Manual Execute X Commands sent to the Digital488 will result in no action until the unit is instructed to execute these commands This is done by sending an X usually as the last character of a command string Commands sent without an X are stored in the internal buffer until an X is received Any number of Execute commands may be inserted into the same command string Certain commands such as Bit Set require an X after each command in a string if more than one of that command is within the same string Example CLEAR 718 reset the Digital488 OUTPUT TL39 TE2T send F2 to the Digital488 command input buffer OULPUT ILOK instruct the Digital488 to execute its command input buffer OUTPUT 718 TAIXA2X Two Bit Set A commands are within the same string requiring an X after each command Format Fn The Format command determines the method by which input and output data will be described Six data formats are available
40. evices and move the print head accordingly However not all devices support the full set of positioning codes B 3 B 4 Decimal Values 00 to 31 ACG amp UCG Descriptions ASCII Control Codes 00 to 31 Dec Name Deseripti n Addressed Command Group ACG Null NUL Space filler character Used in output timing for some device drivers Yes answer to questions or ready for next transmission Used in asynchronous protocols for timing Shift In SI Next characters revert to ASCII meaning Universal Command Group UCG Data Link Escape DLE Used to control transmissions using escape sequences No answer to questions or errors found re transmit Used in asynchronous protocols for timing Unit Separator US Marker for most minor portion of transmission 1 ASCII control codes are sometimes used to formalize a communications session between communication devices 2 DC1 DC2 DC3 DC4 FS GS RS and US all have user defined meanings and may vary in use between sessions or devices 3 DC4 is often used as a general stop transmission character 4 Codes used to control cursor position may be used to control print devices and move the print head accordingly However not all devices support the full set of positioning codes Decimal Values 32 to 63 LAG ASCII Character Set Decimal 32 to 63 Dec Hex Character Name Bus Message Listen Address Group
41. ge the active state of any of the handshake lines HO The Clear line is pulsed H1 The Strobe line is pulsed H2 The Trigger line is pulsed Example OUTPUT 718 HIX the Strobe line is pulsed Inhibit Qn The Inhibit control command allows software control of the Inhibit line independent of any other I O activities The set and clear levels of the Inhibit line are determined by the Invert command Q0 Clear the Inhibit line return to unasserted state Q1 Set the Inhibit line place in the asserted state Example CLEAR 718 reset the Digital488 OUTPUT FLO 01x set the Inhibit line Invert In The Invert command is used to change the polarity of the handshake and data lines At power up all handshake and control lines are active high logic one 5 volts The Invert command can selectively change the polarity of each of the handshake lines and of the data lines If multiple Invert commands are contained within the same string then an Execute command X should be included between each Invert command An alternative is to add the values of each Invert command desired and send one command with the sum of the desired commands The Invert commands are ORed together as received To delete any one command it is necessary to program the default mode I0 then reprogram the desired commands 10 All control lines are active high all data lines are high true I1 Inhibit output is active low I2 Trigger output is active low I4 Data Strobe
42. he first command to be sent after power on All ports programmed as outputs will be set to a logic zero after receiving the Configure command The actual output level is dependent on the Invert command 116 Cn Mode n 0 thru 5 defines which ports are input and output Port 5 4 3 2 l CO in in in in in C1 in in in in out C2 in in in out out C3 in in out out out C4 in out out out out C5 out out out out out in programmed as an input port out programmed as an output port Example CLEAR 718 reset the Digital488 OUTPUT TISSU select port 1 as output ports 2 thru 5 as inputs 3 2 Command Descriptions 7 17 01 Digital488 User s Manual Data Dn Z The Data command outputs up to 40 bits of data to the output ports The number of bits which can be sent with the Data command 1s limited by the number of bits programmed as outputs For formats FO through F3 1f the amount of data sent 1s less than the number of bits programmed as outputs the least significant bits will contain the data sent and the most significant bits will be cleared to logic zero If a single port is selected with the Port command only eight bits may sent with the Data command The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the selected ports For formats FO through F3 data sent by the controller is contained within a prefix D and a suffix Z In format F4 the five bytes immediately following the prefix D
43. he most significant bits will be cleared to logic zero If the data sent is greater than the number of bits programmed for output or selected by the Pn command the Digital488 will generate a conflict error and ignore the entire command string The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the selected port s When the Digital488 is addressed to talk RO it asserts Inhibit reads the data from all ports unasserts Inhibit and outputs the number of characters determined by the Gn and Pn commands Leading zeros are not suppressed and the bus terminators are appended to the output After output the Digital488 must be re addressed to talk to perform subsequent reads EDR R1 may also be used to capture data in this format Example OUTPUT 7187 tk2x select ASCII binary mode ENTER 718 AS read data from the Digital488 DISP AS display shows 0001 1111 1111 0001 OUTPUT LS ADIOS TO IO OTIS ENTER 718 AS read data from the Digital488 DISP AS display shows 1111 0000 1010 0101 F3 Format ASCII Decimal In the F3 format the data is described in decimal 8 bit multiples and transmitted in ASCH Each decimal number O to 255 to be output must be separated by semicolons F3 Number Decimal Equiv F3 Number Decimal Equiv 000 0 008 8 001 1 009 9 002 2 010 10 003 3 020 20 004 4 100 100 005 3 200 200 006 6 210 210 007 7 255 255 Digital488 User s Manual 7 17 01 Command Descriptions 3 7 Dat
44. iate I O port Digital488 32 OEM The Digital488 32 0 EM is a 4 in by 4 in 32 I O line interface board for transferring data between the IEEE 488 GBIP HP IP bus and devices equipped with up to 32 bit wide digital ports The Digital488 32 OEM s 32 TTL level digital I O lines are programmable in 4 bit ports as either inputs or outputs When addressed to talk the Digital488 32 OEM will output data from all thirty two bits or a selected 8 bit port The board also offers six handshake lines for implementing clear data strobe external data ready inhibit trigger and SRQ functions Its firmware includes a complete command set for facilitating the implementation of all its functions This command set is identical to that employed by the other board level and external interfaces in IOtech s industry standard Digital488 family facilitating quick prototyping and making the Digital488 32 OEM compatible with other Digital488 family units Digital488 User s Manual 11 28 01 Introduction 1 1 Available Accessories Additional accessories that can be ordered for the Digital488 include CA 7 1 1 5 foot IEEE 488 Cable CA 7 2 6 foot IEEE 488 Cable CA 7 3 6 foot shielded IEEE 488 Cable CA 7 4 6 foot reverse entry IEEE 488 Cable CA 8 507 6 foot 50 conductor ribbon cable with a card edge connector on one end the other end un terminated CA 46 40 6 foot digital 1 O header connector to ribbon cable for the Digital488 32 0EM CN 6 507 50 Pin so
45. ify KO EOI enabled KI EOI disabled M Service Request MO SRQ is disabled M1 SRQ on Service input transition M2 SRQ on EDR input transition M4 SRQ on Bus error MS SRQ on Test error M16 SRQ on Ready Note the status indication reflects the sum of all received Service Request commands P Selected Port PO All ports selected P1 Port 1 selected P2 Port 2 selected P3 Port 3 selected P4 Port 4 selected PS Port 5 selected R Data Ready RO Data 1s not latched but 1s read when Digital 488 1s addressed to talk R1 Data is latched on EDR transition T Test LED TO Perform RAM and ROM test Y Terminator YO CR LF YI LF CR Y2 CR only Y3 LF only Terminator Yn The IEEE 488 bus terminator defaults at power on to the settings on Switch S1 It also may be programmed for any combination of Carriage Return CR and Line Feed LF The YO mode is the most commonly accepted terminator CR LF Y1 reverses the sequence to send LF CR Y2 sends CR only and Y3 sends LF only YO CR LF YI LF CR Y2 CR only Y3 LF only Example CLEAR 71 8 OUTPUT Tiles vax select line feed terminator 3 14 Command Descriptions 7 17 01 Digital488 User s Manual Test TO The Test command 1s used to verify hardware and LED operation TO Perform RAM and ROM test The TO command will cause the Digital488 to initiate a ROM RAM test If the test is successful all LEDs will flash for one half second If a test fails the Error LED will remain
46. illuminated Use the Status command to determine the cause of the self test error Example CLEAR 718 reset the Digital488 OUTPUT 71 84 7T0X send self test command Digital488 User s Manual 7 17 01 Command Descriptions 3 15 Note 3 16 Command Descriptions 7 17 01 Digital488 User s Manual IEEE 488 Primer 4 History The IEEE 488 bus is an instrumentation communication bus adopted by the Institute of Electrical and Electronic Engineers in 1975 and revised in 1978 The Digital488 conforms to this most recent revision designated IEEE 488 1978 Prior to the adoption of this standard most instrumentation manufacturers offered their own versions of computer interfaces This placed the burden of system hardware design on the end user If his application required the products of several different manufacturers then he might need to design several different hardware and software interfaces The popularity of the IEEE 488 interface sometimes called the General Purpose Interface Bus or GPIB is due to the total specification of the electrical and mechanical interface as well as the data transfer and control protocols The use of the IEEE 488 standard has moved the responsibility of the user from design of the interface to design of the high level software that 1s specific to the measurement application General Structure The main purpose of the GPIB is to transfer information between two or more devices A device can be either an inst
47. is interpreted as data and the suffix Z is not used For the high speed binary F5 format all bytes received are treated as data and the prefix and suffix are not used Refer to the Fn command for additional details Dn Z n represents the data to be outputted terminated by Z In the F4 mode the Z terminator is not allowed Example CLEAR 718 ODIPUT hey CSR OUTPUT 21837 D554x ENTER 118 AS DISP As OUTPUT bos rox OUTPUT TLOoSUDL254950790902X ENTER 718 A DIOR AS OUTEUI T195290129224X ENTER 718 AS DISP AS OUTPUT 718 P5D21ZX OUTEUT dio Bu ENTER IOS AS DISP AS Digital488 User s Manual reset the Digital488 all ports as output select port 1 send 55 to port 1 read data from port 1 display shows 55 select all ports send data to all 40 bits read data from the Digital488 display shows 1234567890 send 12 bits of data to the least significant bits read data from the Digital488 display shows 0000000123 set port 5 only select all ports read data from the Digital488 display shows 2100000123 7 17 01 Command Descriptions 3 3 Data Ready Rn The Data Ready command enables digital input data to be latched When used in conjunction with the Service Request M2 command the External Data Ready line can both latch the input data and signal the controller that new data is available In the default mode RO data is read when the Digital488 is addressed to talk In the R1 mode i
48. ital488 are determined by SW1 6 through SW1 8 The terminator switches are read only at power on but can be changed by the controller through the Terminator command If power is cycled after receipt of the Terminator command then the unit will again default to the switch settings The factory default settings are Carriage Return Line Feed with EOI asserted The Digital488 ignores all terminators received from the bus controller Only the Execute command X is used to signal the Digital488 that a command string has been completed EOI Enabled EOI Disabled SWI View for Terminator Selection Digital Input Output Ports The Digital488 has 40 data lines which can be programmed in groups of 8 as either input or output At power on all 40 bits are in the input mode Each 8 bit group 1s one port beginning with Port 1 as the least significant 8 bits and Port 5 as the most significant 8 bits The Digital488 32 OEM has 32 data lines which can be programmed in groups of 8 as either input or output Each 8 bit group is one port beginning with Port 1 as the least significant 8 bits and Port 4 as the most significant 8 bits Logic Levels The data and handshake output lines will drive two TTL loads In addition ports 1 and 2 outputs are 5 Volt CMOS compatible All input lines are less than 1 5 TTL loads All inputs are protected against damage due to high static voltages Normal precautions should be taken to limit the input voltages to
49. ital488 expects the D prefix followed by five bytes of data beginning with PORTS without the Z suffix If any digital I O port is configured as input the data to that input port will be ignored When the Digital488 is addressed to talk RO it asserts Inhibit reads the data from all ports unasserts Inhibit and outputs 5 bytes beginning with PORTS with EOI asserted on the last bye Bus terminators with the exception of EOI are not appended to the output After output the Digital488 must be re addressed to talk to perform subsequent reads EDR R1 may also be used to capture data in this format F5 Format High Speed Binary In the F5 high speed binary format the command interpreter is disabled When addressed to listen the Digital488 treats all bytes received as data to be output to the Digital I O ports Each time it receives five bytes or detects EOI asserted it pulses the Data Strobe for approximately 15 microseconds Data is expected ina PORTS PORT4 PORT3 PORT2 PORTI sequence If only two bytes are received with EOI asserted on the second byte the Digital488 will update PORTS with the first byte received PORT4 with the second and pulse the Data Strobe Since the interface treats all received characters as data the Un command will not be recognized To place the Digital488 in the F5 format the 3 character string F5X should be the last command sent to the interface without terminators Any characters appended to this comman
50. lder tab edge connector CN 20 Right Angle IEEE 488 adapter male and female CN 22 IEEE 488 Multi tap bus strip four female connectors in parallel CN 23 IEEE 488 panel mount feed through connector male and female Rack488 3 5 1 4 by 19 rack mount for one Digital488 Rack488 4 5 1 4 by 19 rack mount for two Digital488s TR 21 110 volt Wall mount power supply for the Digital488 TR 2E7 220 volt Wall mount power supply for the Digital488 TR 5 110 volt Wall mount power supply for the Digital4880EM TR 5E 220 volt Wall mount power supply for the Digital4880EM For use with Digital488 Only Specifications Digital488 Specifications Digital I O Terminal Installation Category Standard Not Applicable CE Category 1 Transistor Transistor Logic TTL Levels Outputs will drive 2 TTL loads Connector One 50 pin card edge mating connector supplied 1 2 Introduction 11 28 01 Digital488 User s Manual IEEE 488 CAUTION The IEEE 488 terminal must only be used to control a non isolated IEEE 488 system The common mode voltage cable shell to earth must be zero Terminal Installation Category Standard Not Applicable CE Category 1 Implementation SHI AHI T6 TEO L4 LEO SRI RLO PPO DC1 DTI CO El Terminators Selectable CR LF LF CR and CR LF with EOI Programmable IEEE Terminators EOI SRQ Mask Port Data Active Levels Handshake Lines Format and Configuration Connector Standard IEEE 488 conn
51. listen is quite simple Suppose a college instructor 1s presenting the day s lesson Each student is told to raise their hand if the instructor has exceeded their ability to keep up while taking notes If a hand is raised the instructor stops his discussion to allow the slower students the time to catch up In this way the instructor is certain that each and every student receives all the information he is trying to present Since there are many students in the classroom this exchange of information can be very slow In fact the rate of information transfer is no faster than the rate at which the slowest note taker can keep up The instructor though may have a message for one particular student The instructor tells the rest of the class to ignore this message Unlisten and tells it to that one student at a rate which he can understand This information transfer can then happen much quicker because it need not wait for the slowest student Digital488 User s Manual 11 20 01 IEEE488 Primer 4 1 The GPIB transfers information in a similar way This method of data transfer is called handshaking More on this later For data transfer on the IEEE 488 the Active Controller must a b c d 4 2 IEEE 488 Primer Unlisten all devices to protect against eavesdroppers Designate who will talk by addressing a device to talk To Other Devices Device 1 System Controller Able to Talk Listen and Control DMM Able to Talk
52. o as uniline single line commands The signals are active low i e a low voltage represents a logic 1 asserted and a high voltage represents a logic O unasserted Attention ATN ATN is one of the most important lines for bus management If Attention is asserted then the information contained on the data lines is to be interpreted as a multiline command If it is not then that information is to be interpreted as data for the Active Listeners The Active Controller is the only bus device that has control of this line Interface Clear IFC The IFC line is used only by the System Controller It is used to place all bus devices in a known state Although device configurations vary the IFC command usually places the devices in the Talk and Listen Idle states neither Active Talker nor Active Listener Remote Enable REN When the System Controller sends the REN command bus devices will respond to remote operation Generally the REN command should be issued before any bus programming is attempted Only the System Controller has control of the Remote Enable line End or Identify EOl The EOI line is used to signal the last byte of a multibyte data transfer The device that is sending the data asserts EOI during the transfer of the last data byte The EOI signal is not always necessary as the end of the data may be indicated by some special character such as carriage return The Active Controller also uses EOI to perform a Par
53. output is active low I8 Clear output is active low 116 Data is low true 132 EDR input is falling edge sensitive 164 Service input is falling edge sensitive Example CLEAR 718 reset the Digital488 OUTPUT LS T132X264X select EDR and Service input as falling edge sensitive Note OUTPUT 7164 196x performs the same function as above Digital488 User s Manual 7 17 01 Command Descriptions 3 9 Port Pn The Port command determines which port 1s selected for data input output In the default mode P0 all ports are selected The P1 thru P5 commands select a specific eight bit port It is recommend that the Bus Output command be used with the PO mode to determine which ports will be output when the Digital488 is addressed to talk Data in modes P1 through P5 will be input or output in groups of eight bits PO All five ports are selected P1 Port 1 is selected P2 Port 2 is selected P3 Port 3 is selected P4 Port 4 is selected P5 Port 5 is selected Example CLEAR 718 reset the Digital488 OUTPUT 74184 PAM select port 4 Service Request Mask SRQ Mn The Service Request SRQ mode is used by the Digital488 to alert the controller to one of several conditions described below Multiple SRQ conditions can be enabled simultaneously by issuing them separately or by combining them in one command If multiple SRQ commands are contained within the same command string each SRQ command should be followed by an Execute command X The programmed
54. rent limited This is a powerful bus feature that removes the burden from the System Controller to periodically inquire Are you done yet Instead the Controller says Do what I told you to do and let me know when you re done or Tell me when something is wrong Since SRQ is a single line command there is no way for the Controller to determine which device requested the service without additional information This information 1s provided by the multiline commands for Serial Poll and Parallel Poll Suppose the Controller receives a service request For this example let s assume there are several devices that could assert SRQ The Controller issues an SPE Serial Poll enable command to each device sequentially If any device responds with DIO7 asserted it indicates to the Controller that it was the device that asserted SRQ Often times the other bits will indicate why the device wanted service This Serial Polling sequence and any resulting action is under control of the software designer The Parallel Poll is another way the Controller can determine which device requested service It provides the who but not necessarily the why When bus devices are configured for Parallel Poll they are assigned one bit on the data bus for their response By using the Status bit the logic level of the response can be programmed to allow logical OR AND conditions on one data line by more than one device When SRQ is asserted the Controller under user s
55. rument or a computer Before any information transfer can take place it is first necessary to specify which will do the talking send data and which devices will be allowed to listen receive data The decision of who will talk and who will listen usually falls on the System Controller which is at power on the Active Controller The System Controller is similar to a committee chairman On a well run committee only one person may speak at a time and the chairman is responsible for recognizing members and allowing them to have their say On the bus the device which is recognized to speak is the Active Talker There can only be one Talker at a time if the information transferred is to be clearly understood by all The act of giving the floor to that device is called Addressing to Talk If the committee chairman can not attend the meeting or if other matters require his attention he can appoint an acting chairman to take control of the roceedings For the GPIB this device becomes the Active Controller At a committee meeting everyone present usually listens This is not the case with the GPIB The Active Controller selects which devices will listen and commands all other devices to ignore what is being transmitted A device is instructed to listen by being Addressed to Listen This device is then referred to as an Active Listener Devices which are to ignore the data message are instructed to Unlisten The reason some devices are instructed to Un
56. s serial poll response until it is serial poll disabled by the controller Serial Poll Disable SPD Disables the Digital488 from responding to serial polls by the controller Unlisten UNL UNL places the Digital488 in the Listener Idle State Untalk UNT 2 8 Getting Started UNT places the Digital488 in the Talker Idle State 11 19 01 Digital488 User s Manual Installation To begin operating the Digital488 plug the external power supply into the rear jack on the interface CAUTION Never install the power supply into the interface while it is connected to AC line power Failure to observe this caution may result in damage to the Digital488 WARNING Do not use this interface outdoors The interface is intended for indoor use only j Outdoor conditions could result in equipment failure bodily injury or death After installing the power supply connector into the interface turn on the Digital488 by depressing the rear panel power switch All the front panel LEDs should light for approximately one second while the Digital488 performs an internal ROM and RAM self check At the end of this self check all indicators should turn off except POWER If you obtain the above response then your Digital488 is alive and well If all LEDs remain on then a ROM error has occurred If all LEDs continue to flash except the power LED then a RAM error has occurred Try cycling the power to the Digital488 to determine that th
57. software conducts a Parallel Poll The Controller must then analyze the eight bits of data received to determine the source of the request Once the source is determined a Serial Poll might be used to determine the why Of the two polling types the Serial Poll is the most popular due to its ability to determine the who and why In addition most devices support Serial Poll only 4 6 IEEE 488 Primer zoo Digital488 Users Manual Service Information 5 Factory Service IOtech maintains a factory service center in Cleveland Ohio If problems are encountered in using the Digital488 you should first telephone the factory Many problems can be resolved by discussing the problems with our applications department If the problem cannot be solved by this method you will be instructed as to the proper return procedure Theory of Operation The Heart of the Digital488 is a 6809 microprocessor U101 supported by 8K bytes of firmware EPROM U102 2764 and 8K bytes of static RAM U103 6264 A Versatile Interface Adapter U104 65B22 is used to generate real time interrupts for the firmware operating system The front panel annunciators are also driven by U104 through an inverter U113 74LS04 The IEEE 488 bus interface is accomplished by a TMS9914A U106 controller with drivers U107 and U108 The digital I O ports are controlled by PIA s U202 U204 68B21 SWI is read through one port of U204 Power 1s supplied by an external unr
58. t will wait for the selected External Data Ready EDR transition before reading the data and formatting 1t for output If the Digital488 is addressed to talk before EDR is asserted the bus will hang up until the EDR pulse occurs Once EDR is asserted the data will remain latched until the interface is addressed to talk and the data is read by the controller If EDR transitions again before the previous EDR buffered data has been output the Digital488 will generate an EDR Overrun error and ignore the EDR read request After output in the FO through F4 formats the Digital488 must be re addressed to talk to perform subsequent buffered output of EDR captured data EDR cannot be used to capture data in the F5 high speed binary format The EDR signal must be at least 1 microsecond wide and should have a rise and fall time of less than 1 0 microsecond The EDR line defaults to rising edge sensitive but can be changed to falling edge sensitive with the Invert command 132 RO Data is not latched and is read whenever the Digital488 is addressed to talk R1 Data 1s latched on an EDR transition Example CLEAR 718 reset the Digital488 OUTPUT TAS Rix data 1s only read after a rising edge signal is applied to the EDR line End or Identify EOI Kn The EOI line is one of five interface management lines on the IEEE 488 Bus It is used by a talker to indicate the end of a multiple byte transfer sequence At power on the setting of Switch S1 determin
59. tor network The pin out table for the LED status header is located in Figure 1 1 PIN LED CONNECTOR E O mmmum 6 Listn Anode 8 Talk Anode 9 Power Cathode Figure I 1 LED Indicators mm mmm de e Power User supplied 5 volts 0 25 at 1 amp Mating power connector with 8 inch leads provided WARNING Do not use this interface outdoors The interface is intended for indoor use only Outdoor conditions could result in equipment failure bodily injury or death CAUTION Never disassemble the interface case while it is connected to the AC power line Internal voltage potentials exist which could cause bodily injury or death Digital488 User s Manual 11 28 01 Introduction 1 5 Abbreviations 1 6 Introduction The following IEEE 488 abbreviations are used throughout this manual addr n ATN CA CR data DCL GET GTL LA LAG LF LLO MLA MTA PPC PPU SC SDC SPD SPE SRQ TA TAD TCT term UNL UNT IEEE bus address n Attention line Controller Active Carriage Return Data String Device Clear Group Execute Trigger Go To Local Listener Active Listen Address Group Line Feed Local Lock Out My Listen Address My Talk Address Parallel Poll Configure Parallel Poll Unconfigure System Controller Selected Device Clear Serial Poll Disable Serial Poll Enable Service Request Talker Active Talker Address Take Control Terminator Unlisten Untalk Unasserted
60. vated with the corresponding I O activity and can be independently activated with the Handshake Hn command Note that the pin numbers for the Digital488 32 OEM are different from the pin numbers for the Digital488 Clear Digital488 Pin 41 Digital488 32 0EM Pin 33 The Clear output is pulse for approximately 50 microseconds after a Device Clear DCL Selected Device Clear SDC or Interface Clear IFC command has been sent on the bus The Clear line is normally active high The Invert command 18 will program it active low The Handshake command H0 can pulse the Clear line independent of any I O operations DCL SDC or IFC LEE 65 us typ lg 50 us typ gt Timing Diagram for Clear Output Data Strobe Digital488 Pin 42 Digital488 32 OEM Pin 37 The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the I O port The Data Strobe line is normally active high but may be programmed active low by the Invert command 14 The Handshake command H1 can pulse the Data Strobe line independent of an I O operation DATA DATA VALID 15 us min gt Le 50 us typ 15 us typ in F5 Format STROBE Timing Diagram for Strobe Output Digital488 User s Manual 11 19 01 Getting Started 2 5 External Data Ready EDR Digital488 Pin 46 Digital488 32 OEM Pin 36 The External Data Ready EDR line is an edge sensitive input which is used to latch input data It is used in conjunction
61. ways a logic zero Example CLEAR 718 reset the Digital488 OUTPUT 7198 MA4X select SRQ on Bus error OUTPUT 7187 ETX send an invalid bus command ERROR and SRQ LEDs should illuminate SPOLL 718 display should be 84 64 16 4 Sixty four denotes the Digital488 was the source of the SRQ Sixteen denotes the Digital488 is READY for more commands Four denotes a Bus error When serial polled the SRQ LED will turn off Status Un The Status command U0 will cause the Digital488 to send the status message when next addressed to talk The status of the Digital488 may be read at any time without interfering with normal operation Any error conditions are cleared after the status string is read by the controller The Status command Un also enables the controller to read any single bit from the I O ports U1 through U40 U0 Send the Digital488 status when next addressed to talk Un Send the status of bit n 1 thru 40 when next addressed to talk The format of the status byte returned by the Digital488 after receiving a U0 command is as follows C E F G 1 K M P R Y where each equals the number corresponding to that command The leading information is the revision level of the Digital488 firmware Example DIM AS 50 dimension AS CLEAR 718 reset the Digital488 OUTPUT 718 MOR send UO to the Digital488 ENTER 718 AS read the status byte DISP AS display 1 0COEOFO0GOIOO0KO0MOOOPOROYO 3 12 Command Descriptions 7 17
62. whether input port data output port data or both will be transmitted on the bus when the Digital488 is addressed to talk The amount of data sent is dependent on the Pn command The GO default mode causes all input and output port data to be sent to the controller when addressed to talk The G1 mode causes only data from the ports programmed as inputs to be returned when addressed to talk The G2 mode causes only data from ports programmed as outputs to be returned when addressed to talk If all ports are programmed as outputs with G1 selected and the Digital488 is addressed to talk nothing will be transmitted and the bus will hang The converse will also cause the bus to hang with all ports programmed as inputs and G2 selected G0 Input and output port data is send on talk Gl Only input port data 1s sent on talk G2 Only output port data 1s sent on talk Example CLEAR 718 reset the Digital488 OUTPUT 7418 POCIX port1 as output ports 2 5 as input OUTPUT 4187 GlX select only input ports ENTER 718 AS read data from the input ports DESP AS display shows FFFFFFFF data is dependent on what is connected OUTPUT Wes Ez select output ports ENTER 718 AS read data from the output ports DISP XS display shows 00 outputs default to 0 Configure Cn Ports 1 thru 5 are configured as inputs or outputs with the Configure command Each port is eight bits wide At power on all ports are initialized as inputs The Configure command is usually t
63. wo bytes are received with EOI asserted on the second byte the Digital488 will update PORT5 with the first byte received PORTA with the second and pulse the Data Strobe If using Digital488 32 0EM will update PORTA with the first byte received and PORT3 with the second and pulse the Data Strobe Since the interface treats all received characters as data the Status Un command will not be recognized Device Clear DCL and SDC In the FO thru F4 formats Device Clear resets the Digital488 to power on defaults and pulses the Clear output line for approximately 50 microseconds In the high speed binary format F5 it enables the command interpreter and changes the format to FO All other parameters remain unchanged In addition the Clear output line is not pulsed by DCL or SDC when the interface is in FS This is the only programmable method to exit the F5 format Group Execute Trigger GET When the Digital488 recognizes a GET it pulses the Trigger output line for approximately 50 microseconds Interface Clear IFC IFC places the Digital488 in the Talker Listener Idle State and pulses the Clear output line for approximately 50 microseconds Serial Poll Enable SPE When Serial Poll Enabled the Digital488 sets itself to respond to a serial poll with its serial poll status byte if addressed to talk When the serial poll byte is accepted by the controller any pending SRQs are cleared The Digital488 will continue to try to output it
64. yte data transfers 50 us typ INHIBIT DATA VALID pali 50 uS max HA 50 us typ DATA 10 us min l us p pu EDR gt Timing Diagram for EDR Input and Inhibit Output Trigger Digital488 Pin 43 Digital488 32 OEM Pin34 The Trigger output is pulse for approximately 50 microseconds after a GET Group Execute Trigger command is received from the bus controller The trigger pulse is normally active high but can be made active low with the Invert command 12 The Handshake command H2 can independently pulse the Trigger line independent of any bus activity GET y Trigger O RA pes uS typ 450 uS typ gt Timing Diagram for Trigger Output 2 6 Getting Started 11 19 01 Digital488 User s Manual Service Digital488 Pin 45 Digital488 32 OEM Pin35 The Service input is an edge sensitive input capable of generating a bus Service Request SRQ It is enabled with the SRQ command M1 and defaults to rising edge sensitive The Invert command 164 can be used to program it to be falling edge sensitive IEEE 488 Bus Implementation The Digital488 implements many of the capabilities defined by the IEEE 488 1978 specification These are discussed in the following sections Those bus uniline and multiline commands that the Digital488 does not support or respond to include Remote Enable REN Parallel Poll PP Go to Local GTL Parallel Poll Configure PPC Local Lockout LLO Parallel
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