Model 2001 Quick Reference SCPI Guide
Contents
1. CALL ENTER reading length 16 status PRINT reading nd program Take readings using the scanner The Model 2001 s optional 10 channel scanner is a simple multiplexor Only one channel can be closed at a time If you close a channel while another one is already closed the first one opens automatically with break before make operation guaranteed You can use the Model 2001 s scanner two ways One is to simply issue a command to close a particular channel before sending other commands to take readings The other way is to program the scan list and let the meter take care of closing the a channel before taking a reading There is a fundamental difference in the Model 2001 s behavior in these two approaches In the scan list a measurement function is bound to each channel so that when the next channel in the list closes the meter switches to the associated function Simply sending a channel close command however does NOT change the measurement function While using the scan list the meter responds to a trigger by first going to the next channel in the list switching to the function bound to that channel before taking a reading The following example program simply measures DC volts channel 1 AC volts on channel 2 and two wire resistance on channel 3 using the ROUTe CLOSe command begin program Program chanrdgs bas Example 2001 program Demonstrates tak2. Demonstrates one shot external triggering For QuickBASIC 4 5 and CEC PC488 interface card Roger Chaplin Tue May 25 09 45 54 EDT 1993 Keithley Instruments Inc Edit the following line according to where the QuickBASIC libraries live on your machine SINCLUDE c qb45 ieeeqb bi Initialize the CEC interface as address 21 CALL initialize 21 0 Reset controls in INIT ARM LAY1 ARM LAY2 and TRIG subsystems and put trigger model in IDLE state CALL SEND 16 rst status CALL SEND 16 trig sour ext coun inf status start everything off and running CALL SEND 16 init status nd program After the Model 2001 receives the INITiate command it stops in the TRIGger layer of the trigger model waiting for a pulse on the external trigger jack Each time a pulse arrives on the external trigger jack the Model 2001 takes one reading Because TRIGger COUNt has been set to INFinity the trigger model never exits from the TRIGger layer You can send the ABORt command to put the trigger model in the IDLE state disabling triggers until another INITiate command is sent Do continuous triggering See the introductory text under Do one shot triggering The following example program sets up the Model 2001 to take readings as fast as it can once it receives an external trigger The actual reading rate will depend upon other factors suc
3. efficient to program the 2001 to T assert the IEEE 488 SRQ line when it is finished rather than T E 488 controller will repeatedly serial polling the instrument An IE typically address the instrument to talk then unaddress it each time it performs a serial poll Each time the Model 2001 is addressed and unaddressed it must devote some of its internal computer resources to the IE T E 488 bus which steals time away from actually taking readings Repeatedly serial polling the Model 2001 will generally reduce its overall reading throughput Therefore use the srq function call The Model 2001 provides a status bit for nearly every operation it can T perform It can be programmed to assert the IEEE 488 SRQ line whenever any of these status bits becomes TRUE or FALSE The IEEE 488 controller your computer can examine the state of the SRQ line without performing a serial poll thereby detecting when the 2001 has completed its task without interrupting it in the process The following example program segment sets up the Model 2001 to assert SRQ when the reading buffer has completely filled then arms the reading buffer initiates readings and waits for the Model 2001 to indicate that the buffer is full This is not a complete program Not shown are the commands to configure the trigger model and
4. reading every 50 milliseconds begin program Program contrilg2 bas Example 2001 program Demonstrates continuous triggering at a specified rate For QuickBASIC 4 5 and CEC PC488 interface card Roger Chaplin Tue May 25 09 46 31 EDT 1993 Keithley Instruments Inc Edit the following line according to where the QuickBASIC libraries live on your machine SINCLUDE c qb45 ieeeqb bi Initialize the CEC interface as address 21 CALL initialize 21 0 Reset controls in INIT ARM LAY1 ARM LAY2 and TRIG subsystems and put trigger model in IDLE state CALL SEND 16 rst status CALL SEND 16 arm lay2 sour ext status CALL SEND 16 trig coun inf sour tim tim 05 status start everything off and running CALL SEND 16 init status nd program After the Model 2001 receives the INITiate command it stops in the ARM LAYer2 layer of the trigger model waiting for a pulse on the external trigger jack After the external trigger signal occurs the 2001 moves to the TRIGger layer Since TRIGger SOURce is set to TIMer a reading is triggered immediately with a subsequent reading triggered every 50 milliseconds Because TRIGger COUNt has been set to infinity the trigger model never exits from the TRIGger layer Generate SRO on buffer full In most cases when your program must wait until the Model 2001 has completed an operation it is most
5. 15 seconds apart and each of the three readings in each group taken as quickly as possible The Model 2001 stores the readings in the buffer and asserts SRQ when the buffer is full The program waits for the SRO then reads the readings from the buffer begin program Program scanlist bas Example 2001 program Demonstrates using the scan list For QuickBASIC 4 5 and CEC PC488 interface card Roger Chaplin Tue May 25 09 46 07 EDT 1993 Keithley Instruments Inc Edit the following line according to where the QuickBASIC libraries live on your machine SINCLUDE c qb45 ieeeqb bi Initialize the CEC interface as address 21 CALL initialize 21 0 Reset controls in INIT ARM LAY1 ARM LAY2 and TRIG subsystems and put trigger model in IDLE state CALL SEND 16 rst status Reset STATus subsystem not affected by RST CALL SEND 16 Stat pres cls status CALL SEND 16 stat meas enab 512 status enable BFL CALL SEND 16 sre 1 status enable MSB 1 RST CALL SI CALL SI sets TRIG SOUR to IMM END 16 trig coun 3 status END 16 arm lay2 sour tim tim 15 status CALL SI END 16 arm lay2 coun 10 status TRACe subsystem is not affected by RST CALL SEND 16 trac poin 30 egr full status CALL SEND 16 trac feed sensl feed cont next status now the buffer is armed C
6. ALL SEND 16 rout scan 1 3 status CALL SEND 16 rout scan func 1 volt dc status CALL SEND 16 rout scan func 2 volt ac status CALL SEND 16 rout scan func 3 res status CALL SEND 16 rout lsel int status start everything off and running CALL SEND 16 init status init jalize readingS while the 2001 is busy taking readings reading S SPACES 2500 WaitSRQ IF NOT srq THEN GOTO WaitSRQ CALL SPOLL 16 poll status IF po 11 AND 64 0 THEN GOTO WaitSROQ CALL SEND 16 form elem read time chan status CALL SEND 16 trac data status CALL ENTER reading length 16 status PRINT reading nd program
7. Do continuous triggering Generate SRQ on buffer full Store readings in the buffer and then read them out Take readings using the scanner 3 Describe the SCPI commands used in the example programs sufficiently that you can extend or otherwise modify the programs to suit your needs SCPI Command Syntax Tree Structure SCPI commands are organized in a tree structure similar to disk directories in most modern computer operating systems Each level in the hierarchy is called a subsystem For example here is the Model 2001 SENSel subsystem which controls the acquisition of readings the n ENSe2 subsystem is the rear panel digital input SENSe 1 DATA FUNCtion lt name gt VOLTage DC RANGe UPPer lt n gt Gl AUTO lt Boolean gt ONC REFerence lt n gt STATe lt Boolean gt ACQuire The command summary table is the usual way of documenting SCPI commands but it does not show the complete command names The complete command name is formed by joining together the components of the name For example the complete name of the STATe command is n ENSel VOLTage DC REFerence STATe The square brackets are not part of the command names Rather they indicate optional parts of the command names more on that later This hierarchical approach permits the same command names to be re used many times For example many subsystems contain
8. Model 2001 Quick Reference SCPI Guide Roger Chaplin June 4 1993 Introduction The Model 2001 DMM is the most flexible and capable instrument ever produced by Keithley The user has direct access to many control settings in the Model 2001 which are hidden from his reach in older instruments This increased capability does however produce increased complexity To help accommodate this increased complexity the Model 2001 incorporates the SCPI command set Because the Model 2001 presents many more control points to the user it generally requires more commands than its older counterparts to perform comparable tasks Also since the command set in Model 2001 is much larger than that of an older instrument finding the right commands to do the job is more difficult Finally SCPI command names are longer than command names in our older instruments sometimes by a great deal This paper is a quick introduction to SCPI in the Model 2001 Its goal is threefold Leg Describe the syntax of SCPI commands and their documentation in the User Manual Included are descriptions of short forms and default nodes which can help you reduce the amount of data you have to send to the instrument thereby improving the performance of your test system 2 Provide some small simple programs which cause the Model 2001 to perform some simple commonly used tasks These are Change function and range Do one shot triggering
9. a STATe command but each one is unique because the complete command name is unique This is analogous to having a file named for example INDEX TXT in each directory of your computer s disk Although all the files have the sam name they are unique because they ar ach in a different directory Long and Short Form Command Names The command names shown above are written with mixed capitalization Every SCPI command name has a short form The notation used in document upper case with the remainder of t shown in lower cas There are no i name you must send the exact shor have to use the mixed capitalizatio in any combination of upper and lower case form and most also have a long ation is to show the short form in he name which creates the long form ntermediate forms of the command or long form However you do not n the Model 2001 accepts commands For example all of the following are valid forms of the SENSel VOLTage DC REFerence command sensel voltage dc referenc sensl volt dc ref stat F ENSL volt DCE fE EnCe STat The varieties are almost endless descriptive text in this paper the All of the example programs use the case Query Commands With few exceptions command is used to set a control po used to determin is simply the command name with a Some commands are actions rather than control point settings com
10. described in Do continuous triggering and Generate SRQ on buffer full begin program Program buffer bas Example 2001 program Demonstrates the reading buffer For QuickBASIC 4 5 and CEC PC488 interface card Roger Chaplin Tue May 25 09 46 54 EDT 1993 Keithley Instruments Inc Edit the following line according to where the QuickBASIC libraries live on your machine SINCLUDE c qb45 ieeeqb bi Initialize the CEC interface as address 21 CALL initialize 21 0 Reset controls in INIT ARM LAY1 ARM LAY2 and TRIG subsystems and put trigger model in IDLE state CALL SEND 16 rst status Reset STATus subsystem not affected by RST CALL SEND 16 Stat pres cls status CALL SEND 16 stat meas enab 512 status enable BFL CALL SEND 16 sre 1 status enable MSB CALL SEND 16 trig coun 20 status TRACe subsystem is not affected by RST CALL SEND 16 trac poin 20 egr full status CALL SEND 16 trac feed sensl feed cont next status start everything off and running CALL SEND 16 init status initialize reading S while the 2001 is busy taking readings reading S SPACES 4000 WaitSRQ IF NOT srq THEN GOTO WaitSRQ CALL SPOLL 16 poll status IF poll S AND 64 0 THEN GOTO WaitSRQ CALL SEND 16 form elem read time status CALL SEND 16 trac data status
11. e May 25 09 46 42 EDT 1993 Keithley Instruments Inc Edit the following line according to where the QuickBASIC libraries live on your machine SINCLUDE c qb45 ieeeqb bi Initialize the Cl EC interface as address 21 CALL initialize 21 0 Reset the SENSel subsystem settings along with the trigger model each R FAD will cause one trigger CALL SEND 16 rst status set range for each function we will measure CALL SEND 16 volt dc rang 1 status CALL SEND 16 volt ac rang 20 status CALL SEND 16 res rang 10e3 status switch to DC volts and take reading CALL SEND 16 func volt dc read status reading SPACES 80 CALL ENTER reading length 16 status PRINT reading switch to AC volts and take reading CALL SEND 16 func volt ac read status reading S SPACES 80 CALL ENTER reading length 16 status PRINT reading switch to 2 wire ohms and take reading CALL SEND 16 func res read status reading S SPACES 80 CALL ENTER reading length 16 status PRINT reading nd program Be aware that the Model 2001 rounds the range parameter to an integer before choosing the appropriate range Sending VOLTage DC RANGe 20 45 will set the Model 2001 to its 20 volt range This is probably not what you want Do one sh
12. h as A D integration time auto zero mode autorange on off etc begin program Program contrigl bas Example 2001 program Demonstrates continuous triggering as fast as the meter can For QuickBASIC 4 5 and CEC PC488 interface card Roger Chaplin Tue May 25 09 45 42 EDT 1993 Keithley Instruments Inc Edit the following line according to where the QuickBASIC libraries live on your machine SINCLUDE c qb45 ieeeqb bi Initialize the CEC interface as address 21 CALL initialize 21 0 Reset controls in INIT ARM LAY1 ARM LAY2 and TRIG subsystems and put trigger model in IDLE state CALL SEND 16 rst status RST sets TRIG SOUR to IMM CALL SEND 16 arm lay2 sour ext status CALL SEND 16 trig coun inf status start everything off and running CALL SEND 16 init status nd program After the Model 2001 receives the INITiate command it stops in the ARM LAYer2 layer of the trigger model waiting for a pulse on the external trigger jack After the external trigger signal occurs the 2001 moves to the TRIGger layer Since TRIGger SOURce is set to IMMediate a reading is triggered immediately with a subsequent reading triggered as soon as the previous one is finished The following example program sets up the Model 2001 to take readings continuously after an external trigger is received The trigger rate set to one
13. he buffer and then read them out The reading buffer in the Model 2001 is very flexible and capable This also makes its controls a little more complex The reading buffer has basically four controls found in the TRACe subsystem There ar commands to control Ts The size of the buffer in readings TRACe POINts lt NRf gt 2h Whether or not extra data is stored with each reading e g channel number time stamp Storing the extra data reduces the maximum size of the buffer TRACe EGRoup FULL include extra data TRACe EGRoup COMPact don t include extra data 3 Where the is data coming from before or after the CALCulatel math post processing TRACe FEED SENSel store unprocessed readings TRACe FEED CALCulatel store math processed readings 4 What event turns the spigot into the buffer on and off TRACe FEED CONTrol NEVer immediately stop storing readings TRACe FEED CONTrol NEXT start now stop when buffer is full TRACe FEED CONTrol ALWays start now never stop TRACe FEED CONTrol PRETrigger start now stop when pretrigger is satisfied The following example program sets up the Model 2001 to take 20 readings as fast as it can into the buffer then reads the data back after the buffer has filled The readings will be stored with timestamp etc but the program reads back only the reading values and timestamp This program uses the techniques
14. ing readings on different scanner channels For QuickBASIC 4 5 and CEC PC488 interface card Roger Chaplin Tue May 25 09 46 19 EDT 1993 Keithley Instruments Inc Edit the following line according to where the QuickBASIC libraries live on your machine SINCLUDE c qb45 ieeeqb bi Initialize the CEC interface as address 21 CALL initialize 21 0 Reset controls in INIT ARM LAY1 ARM LAY2 and TRIG subsystems and put trigger model in IDLE state set function to VOLT DC CALL SEND 16 rst status close channel 1 take DC volts reading CALL SEND 16 rout clos 1 read status reading S SPACES 80 CALL ENTER reading length 16 status PRINT reading close channel 2 take AC volts reading CALL SEND 16 func volt ac status CALL SEND 16 rout clos 2 read status reading S SPACES 80 CALL ENTER reading length 16 status PRINT reading close channel 3 take ohms reading CALL SEND 16 func res status CALL SEND 16 rout clos 3 read status reading S SPACES 80 CALL ENTER reading length 16 status PRINT reading nd program The following example program sets the Model 2001 up use the scan list to measure DC volts on channel 1 AC volts on channel 2 and two wire resistance on channel 3 The meter takes 10 sets of readings with each set spaced
15. lon character at the beginning of the commands A leading colon instructs the Model 2001 to interpret the command starting at the root highest level of the command tree Since the Model 2001 also starts at the root each time you send it a new command the leading colon is not required although the instrument will accept it if you send it You can send multiple commands to the Model 2001 in a single message You separate the commands with a semi colon character When the Model 2001 encounters a command following a semi colon it attempts to interpret the command starting at the level of the previous command unless you precede the second command with a colon For example either of the following command strings programs the Model 2001 to the 20 volt range for DC voltage measurements and to use 5 volts as a rel value the REFerence commands volt dce rang 20 ref 5 ref stat on volt de rang 20 volt dc ref 5 volt dc ref stat on The two command strings are treated identically by the Model 2001 In the first string when the instrument encounters ref 5 it notices the following it is not the first command in the string there is no leading colon on the command the previous command was at the VOLTage DC level Therefore it interprets the command as though it were also at the VOLTage DC level Example Programs All examples presume QuickBASIC version 4 5 or higher a
16. mands have no query form every SCPI command has a corresponding query the present setting of the control point sor For example stat Wherever command names are used in SCPI mixed case notation is used short forms and send them in lower The int in the instrument the query is The query attached These the n ENSel VOLTage DC REFerence ACQuire command is an action not a setting and so has no query form There are also some queries which have no corresponding command For example SENSel DATA causes the instrument to return its latest reading There is no corresponding command because it would be silly to try to jam a reading value into the instrument Default Nodes SCPI utilizes the concept of default nodes Consider th xampl command tree shown above in Tree Structure What s within square brackets is not necessary to send to the instrument but the instrument will accept it if you send it Consider the UPPer command which sets the measurement range To set the Model 2001 to measure 15 volts DC any of the following commands would work Note these are shown all in long form short forms could also be used SENSel VOLTage DC RANGe UPPer 15 SENSe VOLTage DC RANGe UPPer 15 SENSel VOLTage DC RANGe 15 VOLTage DC RANGe UPPer 15 VOLTage DC RANGe 15 There are of course many more combinations Command Syntax Notice in the preceding examples that there is no co
17. nd a CEC IEEE 488 interface card with CEC driver version 2 11 or higher with the f Model 2001 at address 16 on the IEEE 488 bus Change function and range Unlike our older DMMs the Model 2001 has independent controls for each of its measurement functions This means for example that autorange can be turned ON for DC volts while leaving it OFF for AC volts Therefore each function has its own set of SCPI commands for setting the controls specific to that function Another difference is in the parameter to the range command In our older instruments a single number was used to denote each range For example range 1 on a Model 194 is 320 mV full scale while range 1 on a Model 182 is 3 mV full scale The parameter of the SCPI RANGe command is given as the maximum value I wish to measure The instrument interprets this parameter and goes to the appropriate range When you query the range RANGe the instrument sends back the full scale valu the range it is presently on The following example program illustrates changing function and range It sets the range for several functions then takes readings on each of those functions begin program Program funcrng bas Example 2001 program Demonstrates changing function and range taking readings on various functions For QuickBASIC 4 5 and CEC PC488 interface card Roger Chaplin Tu
18. ot triggering Our older DMMs generally have two types of triggering one shot and continuous In one shot each activation of the selected trigger source causes one reading In continuous the DMM is idle until the trigger source is activated at which time it begins taking readings at a T T E 488 E 488 talk IE specified rate Typical trigger sources are IE Group Execute Trigger GET X command External rear panel BNC The trigger controls in the Model 2001 are vastly different from those in our older DMMs Arming the instrument to respond to triggers is implicit in the non SCPI DMMs Simply sending a command to a non SCPI DMM to change any of the trigger controls causes the instrument to arm itself for triggers The SCPI trigger model implemented in the Model 2001 gives you explicit control over the trigger source the TRIGger subsystem a two level control for arming the instrument for triggers the ARM LAYerl and ARM LAYer2 subsystems plus a way for completely disabling triggers the IDLE layer of the trigger model along with the INITiate subsystem Changing any of the settings in the TRIGger subsystem does not automatically arm the Model 2001 for triggers The following example program sets up the Model 2001 to take one reading each time it receives an external trigger pulse begin program Program sgltrig bas Example 2001 program
19. the reading buffer a complete example showing the use of SRO and programming the Model 2001 reading buffer and trigger model is given in the next section The example shown here can be modified for any event in the Model 2001 status reporting system begin program Reset STATus subsystem not affected by RST CALL SEND 16 Stat pres cls status CALL SEND 16 stat meas enab 512 status enable BFL CALL SEND 16 sre 1 status enable MSB CALL SEND 16 trac feed cont next status start everything off and running CALL SEND 16 init statuss WaitSRQ IF NOT srq THEN GOTO WaitSRQ CALL SPOLL 16 poll status IF poll S AND 64 0 THEN GOTO WaitSRQ nd program Notice that after the program has detected an asserted SRO line it serial polls the Model 2001 to determine if it is the device requesting service This is necessary for two reasons Ts Serial polling the Model 2001 causes it to quit asserting the SRQ line 2s In test systems which have more than one IEEE 488 instrument programmed to assert SRQ your program must determine which instrument is actually requesting service Once an event register has caused a service request it cannot cause another service request until you clear it by reading it in this case using STATus MEASurement EVENt or by sending the CLS command Store readings in t
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