Section 3: Functions and features
2606B System SourceMeter® Instrument Reference Manual
3-36
2606B-901-01 Rev. B / May 2018
The arm and trigger counts must be set to control how many times the SMU executes the source and
measure actions. The arm count indicates the number of times to execute the complete sweep. The
trigger count sets the number of loops in the trigger layer. Typically, you set the trigger count to be
equal to the number of points in the configured sweep. If the trigger count is not equal to the number
of points configured in the sweep, then one of the following occurs:
•
If the trigger count is greater than the number of points in a sweep as configured by
smu
X
.trigger.source.linear
Y
()
,
smu
X
.trigger.source.log
Y
()
, or
smu
X
.trigger.source.list
Y
()
, then the SMU will satisfy the trigger count by restarting the
sweep values from the beginning.
•
If the trigger count is less than the number of source values configured, then the SMU will satisfy
the trigger count and ignore the remaining source values.
For example, configure a three-point linear voltage sweep from 1 to 3 V, with the trigger count set to
2. The SMU will output 1 V, 2 V. If the trigger count is set to 6, then the SMU will output the values
1 V, 2 V, 3 V, 1 V, 2 V, 3 V, repeating the source values twice in a single sweep.
Enabling pulse mode sweeps using the end pulse action
Enable pulse mode sweeps using the end pulse action. The example command below illustrates how
to configure pulse mode sweeps by setting the end pulse action:
smua.trigger.endpulse.action = smua.SOURCE_IDLE
Timers can be used to configure the pulse width and period (see
(on page 3-41) for more
information). To disable pulse mode sweeps, set the
smu
X
.trigger.endpulse.action
attribute
to
smu
X
.SOURCE_HOLD
.
SMU event detectors
As shown in the
Using the remote trigger model
(on page 3-33) topic, the source-measure unit (SMU)
has multiple event detectors (see the table below) in order to control the timing of various actions.
Each event detector monitors for the trigger event assigned to the associated stimulus input.
Operation through the trigger model is delayed at the event detector until the programmed trigger
event occurs.
If the stimulus input is set to zero (0), then the SMU continues uninterrupted through the remote
trigger model.
Event detectors
Event detector
Function
Arm
Controls entry into the trigger layer of the trigger model.
Source
Controls execution of the source action.
Measure
Controls execution of the measurement action.
End pulse
Controls execution of the end pulse action.
For the SMU, action overruns occur when a new trigger is detected before the previous trigger has
been acted upon. When the trigger model is configured for asynchronous measurements, a
measurement trigger generates an overrun if the SMU is not ready to start a new measurement.