User's Manual

Chapter 2 Function Reference — Lab_ISCAN_Start
© National Instruments Corporation 2-271 NI-DAQ FRM for PC Compatibles
the NI-DAQ User Manual for PC Compatibles for more information on SCXI channel
assignments.
Range: 1 through 4 for the 516 and Lab and 1200 Series devices in differential mode.
1 through 8 for the DAQCard-500 (single-ended mode only).
1 through 8 for the DAQCard-700 in differential mode.
1 through 8 for the 516 and Lab and 1200 Series devices in single-ended mode.
1 through 16 for the DAQCard-700 and LPM devices in single-ended mode.
gain is the gain setting to be used for the scanning operation. NI-DAQ applies the same gain
to all the channels scanned. This gain setting applies only to the DAQ device; if you are using
SCXI modules with additional gain selection, you must establish any gain you want at the
SCXI module either by setting jumpers on the module or by calling
SCXI_Set_Gain. The
following gain settings are valid for the Lab and 1200 Series devices: 1, 2, 5, 10, 20, 50, 100.
If you use an invalid gain setting, NI-DAQ returns an error. NI-DAQ ignores gain for the
DAQCard-500/700 and 516 and LPM devices.
buffer is an integer array. buffer must have a length equal to or greater than count.
count is the total number of samples to be acquired (that is, the number of A/D conversions
to be performed). For double-buffered acquisitions, count must be even and should be equal
to the buffer size.
Range: 3 through 2
32
– 1 (except the Lab and 1200 Series devices, which are limited to
65,535 unless enabled for double-buffered mode).
sampTimebase is the timebase, or resolution, to be used for the sample-interval counter. The
sample-interval counter controls the time that elapses between acquisition of samples within
a scan sequence.
sampTimebase has the following possible values:
1: 1 MHz clock used as timebase (1 µs resolution).
2: 100 kHz clock used as timebase (10 µs resolution).
3: 10 kHz clock used as timebase (100 µs resolution).
4: 1 kHz clock used as timebase (1 ms resolution).
5: 100 Hz clock used as timebase (10 ms resolution).
If sample-interval timing is to be externally controlled, NI-DAQ ignores sampTimebase and
the parameter can be any value.
sampInterval indicates the length of the sample interval (that is, the amount of time to elapse
between each A/D conversion within a scan sequence).
Range: 2 through 65,535.
The sample interval is a function of the timebase resolution. NI-DAQ determines the actual
sample interval in seconds by the following formula:
sampInterval
*
(sample timebase resolution)