Operator`s manual

Signametrics 46
4.13.3.1 Burst Read Operation
In response to the DMMBurstRead(nDmm, iSettle, iSamples) command, the DMM enters a tight measurement
loop, where it samples the input and returns measurements to the c
alling S/W. For each measurement sent, it takes
iSett l of iSamples * (iSettle + 1) are taken by the DMM, and
f
ples, must be between 1 and 60,000. Setting the Read Interval can help with fine tuning of the
ue .
rieve iSamples readings.
be ready, and pick them
Wend
le + 1 samples, sending only the last sample. A tota
iSamples are sent back. With the Read Interval set to 0, the total time per measurement is (iSettle + 1) * Aperture
time plus the time it takes to transmit the data back. The last is equal to 132µ for Aperture times greater than 625µs,
and 88µs for other apertures. For instance, if iSettle is set to 3, and the Aperture is set to 10ms, the total time per
sample will be 4 * 10ms + 132us = 40.132ms. iSettle may be set to a value between 0 to 250. The total number o
measurements, iSam
sampling timing. Failing to read the measurements at the rate they become available, or not reading all of the
readings will result in communicaiton overrun. Aperture must be set to 160ms or lower value. The Sync output line
maybe turned on to synchronize external devices (DMMSetSync(0, Yes, 1)).
To retrieve the readings, following the iss of the DMMBurstRead command, use the DMMReadMeasurement
For proper operation, you must ret
i = DMMBurstRead(0, 2, 1000) ‘Take two setteling readings per sample, make 1000 measurements
For i = 0 To 1000 – 1 'Tight read loop, need to get them as fast as they come. Read 1000
While DMMReadMeasurement(0, rd(i)) = No ‘ wait for readings to
Next
4.13.3.2 Multiple Trigger Capture Operation
In response to the DMMSetBuffTrigRead (nDmm, iSettle, iSamples, iEdge) command, the DMM waites for
hardware trigger edge of iEdge polarity to make measurements. For each trigger input it makes a measurement(s),
storing the results in its on-board buffer. For each measurement is made up of iSettle + 1 samples, saving only the
last sample. A total of iSamples trigger input pulses are required to complete the capture process, and iSamples are
aved to the buffer. With the Read Interval set to 0,
s the total time per measurement is (iSettle + 1) * Aperture plus
e
i = DMMSetBuffTrigRead(0, 2, 50, LEADING) ‘two setteling readings, 50 samples and positive Edge.
W mpletion
W
the time it takes to save the data to the buffer. The last is equal to 130µ for Aperture times greater than 625µs, and
117µs for other apertures. iSettle may be set to a value between 0 to 250. The total number of measurements,
iSamples, must be between 1 and 80 for Apertur greater than 625µs, 120 otherwise. Setting the Read Interval can
help with fine tuning of the sampling timing. Use the DMMReady() function to monitor completion. Aperture tim
must not exceed 160ms.
hile DMMReady (0) = No ‘ wait for co
end
For i = 0 To Samp - 1 'Read measuremets from buffer.
DMMReadBuffer 0, rd(i)
Next
4.13.3.3 Burst Capture to Buffer
The DMMBurstBuffRead function is similar to the soft Trigger function, DMMTrigger. In response to the
DMMBurstBuffRead (nDmm, iSettle, iSamples) command, the DMM captures iSamples and stores them to the on-
board buffer. For each measurement saved it takes iSettle + 1 samples, saving the last one. With the Read Interval
set to 0, the total time per measurement is (iSettle + 1) * Aperture time plus the time it takes to save the data to the
buffer. The last is equal to 130µ for Aperture times greater than 625µs, and 117µs for other apertures. iSettle may be
set to a value between 0 to 250. The total number of measurements, iSamples, must be between 1 and 80 for Apertur
greater than 625µs, 120 otherwise. Setting the Read Interval can help with fine tuning of the sampling timing. Use
the DMMReady() function to monitor completion. Aperture time must not exceed 160ms.
i = DMMBurstBuffRead(0, 2, 50) ‘two setteling readings, 50 samples and positive Edge.
While DMMReady (0) = No ‘ wait for completion of capture process
Wend
For i = 0 To 50 - 1 'Read measuremets from on-board buffer.
DMMReadBuffer 0, rd(i)
Next