Keithley 2500, Service Manual

Page: 107 / 121

B-10 Calibration Reference Model 2500 Service Manual
Using the *OPC command
The *OPC (operation complete) command can be used to detect the completion of each
calibration step. In order to use *OPC to detect the end of each calibration step, do the
following:
1. Enable operation complete by sending *ESE 1. This command sets the OPC
(operation complete bit) in the standard event enable register, allowing operation
complete status from the standard event status register to set the ESB (event
summary bit) in the status byte when operation complete is detected.
2. Send the *OPC command immediately following each calibration command. For
example:
:CAL:PROT:SENS:VOLT 8;*OPC
Note that you must include the semicolon (;) to separate the two commands, and
that the *OPC command must appear on the same line as the calibration command.
3. After sending a calibration command, repeatedly test the ESB (Event Summary)
bit (bit 5) in the status byte until it is set. (Use *STB? to request the status byte.)
4. Once operation complete has been detected, clear OPC status using one of two
methods: (1) use the *ESR? query, then read the response to clear the standard
event status register, or (2) send the *CLS command to clear the status registers.
Note that sending *CLS will also clear the error queue and operation complete
status.
Generating an SRQ on calibration complete
An IEEE-488 bus SRQ (service request) can be used to detect operation complete instead
of repeatedly polling the Model 2500. To use this method, send both *ESE 1 and *SRE 32
to the instrument, then include the *OPC command at the end of each calibration com-
mand line, as covered above. Clear the SRQ by querying the ESR (using the *ESR? query)
to clear OPC status, then request the status byte with the *STB? query.
Refer to your controller's documentation for information on detecting and servicing SRQs.