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Model 7706 module
Generating an SRQ on error
To program the instrument to generate an IEEE-488 bus SRQ when an error occurs, send the following command: *SRE 4. This
command will enable SRQ when the EAV bit is set. You can then read the status byte and error queue as outlined above to check
for errors, and to determine the exact nature of the error.
Detecting calibration step completion
When sending remote calibration commands, you must wait until the instrument completes the current operation before sending
a command. You can use either *OPC? or *OPC to help determine when each calibration step is completed.
Using the *OPC? query
With the *OPC? (operation complete) query, the instrument will place an ASCII 1 in the output queue when it has completed
each step. To determine when the OPC response is ready, do the following:
1. Repeatedly test the MAV (Message Available) bit (bit 4) in the status byte and wait until it is set. (You can request the status
byte by using the *STB? query or by serial polling.)
2. When MAV is set, a message is available in the output queue, and you can read the output queue and test for an ASCII 1.
3. After reading the output queue, repeatedly test MAV again until it clears. At this point, the calibration step is completed.
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 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 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 cal-
ibration command line, as covered above. Refer to your controller’s documentation for information on detecting and servicing
SRQs.