Section 3: Functions and features
Model 2651A High Power System SourceMeter® Instrument Reference Manual
3-52
2651A-901-01 Rev. A / March 2011
Command interface triggering
A command interface trigger occurs when:
•
A GPIB GET command is detected (GPIB only)
•
A VXI-11
device_trigger
method is invoked (VXI-11 only)
•
A
*TRG
message is received
Use
trigger.EVENT_ID
to monitor for command interface triggers. To ensure that commands and
triggers issued over the command interface are processed in the correct order, a trigger event is not
generated until:
•
The trigger command is executed
•
trigger.wait()
retrieves the trigger command from the input queue before it would normally
be executed
Command interface triggering does not generate action overruns. The triggers are processed in the
order that they are received in the Model 2651A input queue. The Model 2651A does not process
incoming commands while a script is running. Input triggers that are not processed can cause an
overflow in the input queue. It is important to make sure a script processes triggers while it is running.
NOTE
The input queue can fill up with trigger entries if too many
*TRG
messages are received while a test
script is running. This can be averted by using the
localnode.prompts4882
(on page 5-1) for more information), and by using
trigger.wait()
calls that remove
the
*TRG
messages from the input queue. If the input queue fills with too many trigger entries,
messages like
abort
will not be processed.
Manual triggering
The TRIG key is used for manual triggering. Each time the TRIG key is pressed, a trigger event is
generated. You can monitor for a manual trigger event using the event ID
display.trigger.EVENT_ID
. See
Using the TRIG key to trigger a sweep
(on page 3-39) for an
example of how to use a manual trigger.
There are no action overruns for manual triggering.
Interactive triggering
The complexity of some test system configurations may not allow a static trigger setup. These
configurations would require more dynamic control of triggering than the static trigger setup provides.
For such cases, a setup providing interactive trigger programming would allow the generation and
detection of trigger events that can be controlled on demand under remote control. For example,
interactive triggering can be used when you need to make multiple source function changes or
implement conditional branching to other test setups based on recent measurements.
