User's Manual

Chapter 2 Function Reference — SCXI_SCAN_Setup
NI-DAQ FRM for PC Compatibles 2-356
© National Instruments Corporation
Any value in the moduleList array that is greater than the number of slots available in the
chassis (such as a value of 15 or 16) can act as a dummy entry in the module scan list. Dummy
entries are very useful in multichassis scanning operations to indicate in the module scan list
when the MIO or AI is scanning channels on another chassis.
numChans is an array of length numModules that indicates how many channels to scan on
each module represented in the moduleList array. If the number of channels specified for a
module exceeds the number of input channels available on the module, the channel scanning
will wrap around after the last input channel and continue with the first input channel. If a
module is represented more than once in the moduleList array, there can be different
numChans values for each entry. For the SCXI-1200, this parameter depends entirely on its
corresponding startChans value.
Range: numChans[i] = 1 to 128.
startChans is an array of length numModules that contains the start channels for each
module represented in the moduleList array. If a module is represented more than once in the
moduleList array, the corresponding elements in the startChans array should contain the
same value; there can only be one start channel for each module.
startChans[i] = 0 to n–1, where n is the number of input channels available on the
corresponding module, selects the indicated channel as the lowest scanned channel. NI-DAQ
will scan a total of numChans successive channels starting with this channel, on the module
represented by moduleList[i].
(SCXI-1102 and VXI-SC-1102 only)—startChans[i] = c +
ND_CJ_TEMP, where c is a
channel number as described above, selects scanning of the temperature sensor on the
terminal block, followed by successive channels beginning with c. NI-DAQ will scan the
temperature sensor and then a total of numChans-1 successive channels starting with
channel c, for a total of numChans readings on the module represented by moduleList[i].
startChans[i] = –1 selects only the temperature sensor on the terminal block; no channels are
scanned.
Keep in mind that if you use –1 to select the temperature sensor, all readings from that module
will be readings of the temperature sensor only; channel scanning is not possible.
DAQdeviceNumber is the device number of the DAQ device that will perform the channel
scanning operation. If you are using the SCXI-1200 to perform the data acquisition, you
should specify the module logical device number.
modeFlag indicates the scanning mode to be used. Only one scanning mode is currently
supported, so you should always set this parameter to zero.