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Programming the DC Source - 7
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One way to wait for results without tying up the computer is to use the SCPI command completion
commands. For example, you can send the *OPC command after INITialize, then occasionally poll the
OPC status bit in the standard event status register for status completion while doing other tasks. You can
also set up an SRQ condition on the OPC status bit going true and do other tasks until the SRQ interrupts.
Multiple Triggers
As shown in Figure 7-6, the dc source also has the ability to set up several measurements in succession.
This is accomplished by specifying a trigger count.
NOTE: Multiple triggers can only be programmed for voltage and current measurements on the
main output (output 1). Multiple triggers cannot be programmed for DVM
measurements.
trigger level
TRIG:ACQ:COUN:VOLT 3 or
TRIG:ACQ:COUN:CURR 3
trigger 1 trigger 2 trigger 3
Measurement
(Measurement = time interval X # of points)
Measurement
Measurement
Figure 7-6. Multiple Measurements
To set up the trigger system for a number of sequential acquisitions use:
TRIG:ACQ:COUN:CURR <number> or
TRIG:ACQ:COUN:VOLT <number>
With this setup, the instrument performs each acquisition sequentially, storing the digitized readings in
the internal measurement buffer. It is only necessary to initialize the measurement once at the start; after
each completed acquisition the instrument will wait for the next valid trigger condition to start another.
When all measurements complete, use FETCh commands to return the data.
By varying the measurement parameters, you can accurately measure specific portions of an output pulse.
For example, if you set the measurement time to match the pulse width, you can measure just the high
level of a specific number of output pulses. If you increase the measurement time to include the entire
waveform, you will return measurement data based on the entire waveform. To calculate the correct time
interval for your measurement, simply divide the desired measurement time by the number of points or
samples in the measurement.
NOTE: The total number of data points cannot exceed 4096. This means that the count
multiplied by the points in each measurement cannot exceed 4096; otherwise an error
will occur.