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Chapter 2

Function Reference — Lab_ISCAN_Op

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 National Instruments Corporation

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NI-DAQ FRM for PC Compatibles

Range:

1 through 4 for the 516 and Lab and 1200 Series devices in differential mode.
1 through 8 for DAQCard-500 (single-ended mode only).
1 through 8 for DAQCard-700 in differential mode.
1 through 8 for the Lab and 1200 Series devices in single-ended mode.
1 through 16 for LPM devices or DAQCard-700 in single-ended mode.

gain is the gain setting to be used for the scanning operation. The same gain is applied to all 
the channels scanned. This gain setting applies only to the DAQ device; if you use 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, and 
100. If you use an invalid gain, 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 not less than count. When 

Lab_ISCAN_Op

 returns with an error code of zero, buffer contains the acquired data. 

count is the number of samples to be acquired (that is, the number of A/D conversions to be 
performed).

Range:

3 through 2

32

 – 1 (except Lab and 1200 Series devices, which are limited to 

65,535).

sampleRate is the sample rate you want in units of pts/s.

Range:

Roughly 0.00153 pts/s through 62,500 pts/s (Lab and 1200 Series devices).
Roughly 0.00153 pts/s through 50,000 pts/s (DAQCard-500/700 and 516 and 
LPM devices).

scanRate is the scan rate you want in units of scans/s. This is the rate at which NI-DAQ 
performs scans. NI-DAQ performs a scan each time NI-DAQ samples all channels in the scan 
sequence. ScanRate must be slightly less than sampleRate/numChans due to a 5 µs delay 
interval to the driver. 

Lab_ISCAN

 interval scanning is available on the Lab and 1200 Series 

devices only.

Range:

0 and roughly 0.00153 scans/s through 62,500 scans/s.

A value of 0 disables interval scanning.