Model 2750 Multimeter/Switch System Service Manual Calibration Reference B-25
Calibration Reference
Status byte EAV (Error Available) bit
Whenever an error is available in the error queue, the EAV (Error Available) bit (bit 2) of
the status byte will be set. Use the *STB? query or serial polling to obtain the status byte,
then test bit 2 to see if it is set. If the EAV bit is set, an error has occurred, and you can use
the :SYST:ERR? query to read the error and at the same time clear the EAV bit in the sta-
tus byte. Bit 3 of the Standard Event Register will also be set by a calibration error.
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 com-
pletes 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.
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