Section 7: Increasing SMU current sourcing ability Model 2651A High Power System SourceMeter® Instrument User's Manual
Master Model 2651A node[1] trigger model operation
In the master Model 2651A (
node[1]
) trigger model, timer 1 controls the period of the pulse, while
timer 2 controls the pulse width. TSP-Link
®
trigger 1 prompts Model 2651A (subordinate,
node[2]
) to
output its pulse.
When the trigger model of the master Model 2651A (
node[1]
) is initialized, the following occurs:
1. The source-measure unit (SMU) trigger model leaves the idle state, flows through the Arm Layer,
enters the Trigger Layer, outputs the ARMED event trigger, and then reaches the Source Event,
where it waits for an event trigger.
2. The ARMED event trigger is received by timer 1, which begins its countdown and passes the
trigger through to be received by TSP-Link trigger 1, timer 2, and the SMU Source Event
Detector.
3. TSP-Link trigger 1 receives the event trigger from timer 1 and sends a trigger through the
TSP-Link interface to Model 2651A (subordinate,
node[2]
) to instruct it to output the pulse.
4. The SMU Source Event Detector receives the event trigger from timer 1, begins to output the
pulse, waits the programmed source delay (if any), outputs the SOURCE_COMPLETE event to
timer 2, and then allows the SMU trigger model to continue.
5. Timer 2 receives the SOURCE_COMPLETE event trigger from timer 1 and begins to count down.
6. The SMU trigger model continues to the Measure Event, where it waits a programmed measure
delay (if any), takes a measurement, and continues until it encounters the End Pulse Event,
where it waits for an event trigger.
7. The timer 2 countdown expires and timer 2 outputs an event trigger to the SMU End Pulse Event.
8. The SMU End Pulse Event Detector receives the event trigger from timer 2, outputs the falling
edge of the pulse, and allows the SMU trigger model to continue.
9. The SMU trigger model compares the current trigger layer loop iteration with the trigger count.
•
If the current iteration is less than the trigger count, the trigger layer repeats and the SMU trigger model
reaches Source Event, where it waits for another trigger from timer 1. Because timer 1 had its count set
to one less than the trigger count, timer 1 will continue to output a trigger for each iteration of the Trigger
Layer loop. The trigger model then repeats from step 3.
•
If the current iteration is equal to the trigger count, the SMU trigger model exits the Trigger Layer,
passes through the Arm Layer, and returns to an idle state.
Model 2651A node[2] trigger model operation
In the Model 2651A instrument (subordinate,
node[2]
) trigger model, timer 1 controls the pulse width
and is programmed with the same delay as timer 2 in the Model 2651A (master,
node[1]
).
The pulse period is controlled by TSP-Link
®
trigger 1, which gets its triggers from the Model 2651A
instrument (master,
node[1]
) timer 1, so the same timer in the system controls the pulse period.
7-8
2651A-900-01 Rev. A / March 2011
