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Chapter 2 Function Reference — SCAN_to_Disk
NI-DAQ FRM for PC Compatibles 2-316
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National Instruments Corporation
chans is an integer array of a length not less than numChans that contains the onboard
channel scan sequence to be used. chans can contain any analog input channel number in any
order. For channel number ranges, refer to Table B-1 in Appendix B, Analog Input Channel,
Gain Settings, and Voltage Calculation. For example, if numChans = 4 and if chans[1] = 7,
the second channel to be scanned is analog input channel 7, and NI-DAQ scans four analog
input channels.
Note The channels contained in the chans array refer to the onboard channel numbers.
If you use one or more external multiplexer devices (AMUX-64Ts), with any MIO or AI
device except the MIO-64, the total number of channels scanned equals (four-to-one
multiplexer)
*
(number of onboard channels scanned)
*
(number of external multiplexer
devices), or the total number of channels scanned equals (4)
*
(numChans)
*
(num_mux_brds). For example, if you use one AMUX-64T and scan eight onboard channels,
the total number of channels scanned equals (4)
*
(8)
*
(1) = 32.
If you use one or more external multiplexer devices (AMUX-64Ts) with the MIO-64, the total
number of channels scanned equals (4)
*
(numChans1)
*
(num_mux_brds) + numChans2,
where:
• 4 represents a four-to-one multiplexer.
• numChans1 is the number of onboard channels (of an MIO or AI connector) scanned.
Range: 0 through 7 differential, 0 through 15 single-ended.
• num_mux_brds is the number of external multiplexer devices.
• numChans2 is the number of onboard channels (of an analog connector) scanned.
Range: 0 through 23 differential, 0 through 48 single-ended.
If you use SCXI, you must scan the analog input channels on the DAQ device that
corresponds to the SCXI channels you want. You should select the SCXI scan list using
SCXI_SCAN_Setup before you call this function. Refer to the NI-DAQ User Manual for
PC Compatibles for more information on SCXI channel assignments.
gains is an integer array of a length not less than numChans that contains the gain setting to
be used for each channel in the scan sequence selected in chans. NI-DAQ applies the gain
value contained in gains[n] to the channel number contained in chans[n] when the function
scans that channel. This gain setting applies only to the DAQ device; if you use SCXI, you
must establish any gain you want at the SCXI module either by setting jumpers on the module
or by calling
SCXI_Set_Gain. Refer to Appendix B, Analog Input Channel, Gain Settings,
and Voltage Calculation, for valid gain settings. If you use an invalid gain, NI-DAQ returns
an error.