Picotest M3500A User Manual page 167

Enable "operation complete" by using the *ESE 1 command.
Send the *OPC? command and enter the result to enable
synchronization.
When bit 5 is set in the status byte summary register, please use a
serial poll to check. Then you could set the DMM for an SRQ interrupt
by using *SRE 32.
Usage of the Messages Available Bit (MAV)
You can use the status byte "message available bit 4" to decide when
data is available to read in the bus controller. When the first reading
trigger occurs by using the command TRIGger:SOURce:IMMediate, the
DMM will automatically enable the bit 4. The DMM will clear bit 4 only
after entire messages have been read from the output buffer.
The MAV bit can indicate only when the first reading is generated by the
READ? command. So this will be helpful for you as a trigger event such as
BUS or EXTernal will occur. In addition, the MAV bit is set only after all
specified measurements have completed by using the INITiate and
FETCH? commands. That means in detail, the INITIate command is used
to store readings in the DMM's internal memory. And the FETCH?
command is used to transfer readings to the DMM's output buffer.
Signal by Using *OPC When Data is in the Output Buffer
Normally, to use the "operation complete bit 0" in the standard event
register will signal as a command sequence is completed. The bit is set in
the register after executing an *OPC command. And if you send an *OPC
after a command loading a message in the DMM's output buffer, the
operation complete bit is allowed to be used to determine as the
message is available. However, if there are too many messages
generated before executing the *OPC command, the output buffer will be
filled, and the DMM will be interrupted to take readings.
About the Standard Event Register
The standard event register reports the instrument event types below,
such as power-on detected, command syntax errors, command
execution errors, self-test (calibration errors), query errors or the
moment of executing an *OPC command. Then through the enable
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