Measurement Computing UL for NI LabVIEW - Manual (Page 87)

Universal Library Virtual Instruments (VIs) Streamer File VIs
If the trigger occurs too early, then fewer than the requested number of pre-trigger
samples will be collected. In that case a TOOFEW error will occur. The PretrigCount
will be set to indicate how many samples were collected and the post trigger
samples will still be collected.
TotalCount Specifies the total number of samples that will be collected and stored in the file.
TotalCount must be greater then or equal to PretrigCount + 512. If the trigger
occurs too early then fewer than the requested number of samples will be collected.
In that case a
TOOFEW error will occur. The TotalCount will be set to indicate how
many samples were actually collected.
Rate (input) The maximum sampling rate depends on the A/D board that is being used.
Range If the selected A/D board does not have a programmable range feature, then this
argument will be ignored. Otherwise the gain can be set to any of the ranges that
are supported by the selected A/D board. See the "
Range input values " table on
page 19 for valid values. Refer to board-specific information contained in the
Universal Library User's Guide (available on our web site at
www.mccdaq.com/PDFmanuals/sm-ul-user-guide.pdf ) for the list of ranges
supported by each board.
FileName The name of the streamer file to create.
Use FileRead.VI to read the data from this file.
Refer to the Universal Library User's Guide (available on our web site at
www.mccdaq.com/PDFmanuals/sm-ul-user-guide.pdf ) for information on the
streamer file functions.
ExtClock If this option is used, then conversions will be controlled by the signal on the
external clock input line rather than by the internal pacer clock. Each conversion
will be triggered on the appropriate edge of the external clock input signal (see
board-specific information). When this option is used, the
Rate argument is
ignored. The sampling rate is dependent on the trigger signal.
DTConnect If True, samples are sent to the DT-Connect port if the board is equipped with one.
If False, samples are not output to the DT-Connect port. This is the default.
PretrigCount Actual number of pre-trigger A/D samples collected.
TotalCount Total number of A/D samples collected.
Rate (output) The maximum sampling rate depends on the A/D board that is being used. This is
the rate at which scans are triggered. If you are sampling four channels, 0 to 3, then
specifying a rate of 10,000 scans per second (10 kS/s) will result in the A/D
converter rate of 40 kS/s (four channels at 10,000 samples per channel per second).
This is different from some software where you specify the total A/D chip rate. In
those systems, the per channel rate is equal to the A/D rate divided by the number
of channels in a scan. This argument also returns the value of the actual set. This
may be different from the requested rate because of pacer limitations.
ErrCode Error code returned from the Universal Library. Zero if no error occurred. Use the
ErrMsg VI to convert ErrCode into a readable string.
Notes:
OVERRUN error: This error indicates that the data was not written to the file as fast as the data was sampled.
Consequently, some data was lost. The value in
TotalCount will be the number of points that were
successfully collected.
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