User's Manual

Chapter 2 Function Reference — SCAN_Op
© National Instruments Corporation 2-297 NI-DAQ FRM for PC Compatibles
chans is an integer array of a length not less than numChans that contains the channel scan
sequence to be used. chans can contain any onboard analog input channel number (Range: 0
through 7 differential, 0 through 15 single-ended) number in any order. For onboard analog
input channel ranges, see 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 number 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:
• 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 are using SCXI, you must scan the appropriate analog input channels on the DAQ
device that correspond 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 NI-DAQ 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