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7 - Programming the DC Source
82
Generating Measurement Triggers
Single Triggers
After you specify the appropriate trigger source and sensing function, generate triggers as follows:
GPIB Triggers
Send one of the following commands over the GPIB:
TRIG:IMM (not affected by the trigger source setting)
*TRG
an IEEE-488 Group Execute Trigger bus command
Internal Triggers
To trigger off of the output signal, you must specify the output level that
generates the trigger, the rising or falling edge of the slope, and a hysteresis to
qualify trigger conditions. This is illustrated in figure 7-5 for current triggers.
External Triggers
To externally trigger the measurement, you must supply either a negative-going
edge signal or a contact closure to the external trigger input (see Appendix A).
This capability only applies to units with firmware revision A.03.01 and up.
TRIG:ACQ:SLOP:CURR POS
TRIG:ACQ:LEV:CURR <level>
TRIG:ACQ:HYST:CURR <value>
Trigger occurs on rising edge
when signal crosses positive
hysteresis band limit
TRIG:ACQ:HYST:VOLT <value>
TRIG:ACQ:SLOP:CURR NEG
TRIG:ACQ:SLOP:VOLT NEG
TRIG:ACQ:SLOP:VOLT NEG
TRIG:ACQ:LEV:VOLT <level>
Trigger occurs on falling edge
when signal crosses negative
hysteresis band limit
Measurement time = time interval X number of points
Figure 7-5. Commands Used to Control Internal Measurement Triggers
To specify the current level that will generate triggers for both positive- and negative-going signals use:
TRIG:SEQ2:LEV:CURR <value> or
TRIG:ACQ:LEV:CURR <value>
To specify the slope on which triggering occurs use the following commands. You can specify a
POSitive, a NEGative, or EITHer type of slope.
TRIG:SEQ2:SLOP:CURR <slope> or
TRIG:ACQ:SLOP:CURR <slope>
To specify a hysteresis band to qualify the positive- or negative-going signal use:
TRIG:SEQ2:HYST:CURR <value> or
TRIG:ACQ:HYST:CURR <value>
NOTE: When using internal triggers, do not INITiate the measurement until after you have
specified the slope, level, and hysteresis.
When the acquisition finishes, any of the FETCh queries can be used to return the results. Once the
measurement trigger is initiated, if a FETCh query is sent before the data acquisition is triggered or
before it is finished, the response data will be delayed until the trigger occurs and the acquisition
completes. This may tie up the computer if the trigger condition does not occur immediately.