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D - Example Programs
94
Your application program will not include the dc source’s symbolic name and GPIB address.
These must be specified during configuration (when you run IBCONF.EXE). Note that the primary
address range is from 0 to 30 but any secondary address must be specified in the address range
of 96 to 126. The dc source expects a message termination on EOI or line feed, so set EOI w/last
byte of Write. It is also recommended that you set Disable Auto Serial Polling.
All function calls return the status word IBSTA%, which contains a bit (ERR) that is set if the call
results in an error. When ERR is set, an appropriate code is placed in variable IBERR%. Be sure
to check IBSTA% after every function call. If it is not equal to zero, branch to an error handler that
reads IBERR% to extract the specific error.
Error Handling
If there is no error-handling code in your program, undetected errors can cause unpredictable
results. This includes "hanging up" the controller and forcing you to reset the system. Both of the
above DOS drivers have routines for detecting program execution errors. Error detection should
be used after every call to a subroutine.
BASIC Controllers
The BASIC Programming Language provides access to GPIB functions at the operating system
level. This makes it unnecessary to have the header files required in front of DOS applications
programs. Also, you do not have to be concerned about controller "hangups" as long as your
program includes a timeout statement. Because the dc source can be programmed to generate
SRQ on errors, your program can use an SRQ service routine for decoding detected errors. The
detectable errors are listed in Appendix C.
Example 1. HP Vectra PC Controller Using Agilent 82335 Interface
5 ’-------------------- Merge SETUP.BAS here --------------------
1000 MAX.ELEMENTS=2 :ACTUAL.ELEMENTS=0 :MAX.LENGTH=80 :ACT.LENGTH=0
1005 DIM OUTPUTS(2) :CODES$=SPACE$(40)
1010 ISC=7 :PS=706
1015 ’
1020 ’Set up the DC Source Interface for DOS driver
1025 CALL IORESET (ISC) ’Reset the interface
1030 IF PCIB.ERR <> NOERR THEN ERROR PCIB.BASERR
1035 TIMEOUT=3
1040 CALL IOTIMEOUT (ISC, TIMEOUT) ’Set timeout to 3 seconds
1045 IF PCIB.ERR <> NOERR THEN ERROR PCIB.BASERR
1050 CALL IOCLEAR (ISC) ’Clear the interface
1055 IF PCIB.ERR <> NOERR THEN ERROR PCIB.BASERR
1060 CALL IOREMOTE (ISC) ’Set dc source to remote
mode
1065 IF PCIB.ERR <> NOERR THEN ERROR PCIB.BASERR
1070 ’
1075 ’Program dc source to CV mode with following voltage and current
1080 CODES$ = "VOLTAGE MAX;CURRENT MAX" :GOSUB 2000