Keithley 2700, Service Manual

Page: 160 / 174

B-24 Calibration Reference
Using the *OPC command
The *OPC (operation complete) command can also be used to detect the completion of each
calibration step. To use *OPC to detect the end of each calibration step, you must 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:DC:STEP1;*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 either the *STB? query or serial polling to
request the status byte.)
4. Once operation complete has been detected, clear OPC status using one of two meth-
ods: (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 2700. 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 command line, as
covered above. Refer to your controller’s documentation for information on detecting and ser-
vicing SRQs.