Keithley 4200A-SCS - Page 110

Model 4200A-SCS Pulse Card (PGU and PMU) User's Manual Section 4: Pulse card concepts
4200A-PMU-900-01 Rev. A December 2020 4-21
If you need to define a trigger in using a source-only pulse waveform (2-level or Segment Arb), you
can create a user test module (UTM) that uses the command set described in “Pulse source only
(PG2) commands” in Model 4200A-SCS LPT Library Programming. This allows an external trigger
(LPT command pulse_trig_source) to output a 2-level pulse (LPT commands pulse_vhigh and
pulse_vlow) or seg-arb (LPT command seg_arb_define). This allows for external triggering (a
trigger input into the card) that causes a burst of pulses to be output.
Triggering transition time must be <100 ns. Trigger output Level and Trigger In Level must be TTL.
Details on the trigger functions discussed in the following paragraphs are provided in Model
4200A-SCS LPT Library Programming.
Basic triggering
The pulse output of a pulse card can be started by a software trigger. The LPT function for the
software trigger also sets the trigger mode. Enabled pulse generator channels will then output a
continuous string of pulses (continuous trigger mode), or a burst of pulses (burst or trig burst trigger
mode).
Software trigger source
To use a software trigger to start pulse output, the software trigger source must first be selected. The
pulse_trig_source function is used to select the software trigger source.
Trigger mode
With the software trigger source selected, using the pulse_trig function selects one of the
following trigger modes and initiates (triggers) the start of pulse output:
• Continuous: This trigger mode continuously outputs pulses when pulse output is started.
• Burst or Trig Burst: These trigger modes output a burst of pulses when pulse output is started. A
burst is a finite number of pulses (1 to 2
32
-1). The only difference between burst and trig burst is
the behavior of trigger output (refer to Pulse generator card output trigger (on page 4-22)).
When using the burst or trig burst trigger mode, make sure to first set the pulse count before starting
pulse output. The pulse_burst_count function is used to set the burst count.