National Instruments Measure Data Acquisition - Manual (Page 24)

© National Instruments Corporation 3-1 Measure Data Acquisition User Manual
Using SCXI
with Measure DAQ
This chapter describes how to use the Measure data acquisition (DAQ)
Add-in in Excel with your Signal Conditioning Extension for
Instrumentation (SCXI) equipment.
SCXI is a set of modules and terminal blocks used as a signal condition
front-end for your data acquisition devices. These modules perform
tasks such as multiplexing large numbers of signals, amplifying low-
level signals, providing isolation between your data acquisition devices
and transducers, and so on.
To use your SCXI modules with Measure, first you must configure all
your DAQ hardware using the NI-DAQ Configuration Utility
(
WDAQCONF.EXE ). In the configuration utility, you must assign a
device number to each of your DAQ devices and define the
connections to your SCXI modules. In most cases, your DAQ device is
a plug-in board in your computer although it also can be a PC Card
(PCMCIA) format DAQCard or a SCXI-1200 module. You use the
DAQ devices for the actual A/D conversions of your analog input
signals, and for controlling SCXI modules. Each SCXI module is
controlled by one DAQ device, and is assigned as such in the
configuration utility. If you have any questions about the configuration
utility, consult the NI-DAQ User Manual for PC Compatibles.
Once you have configured the SCXI system, using the Measure DAQ
Add-In is very similar to using a simple DAQ device. The only
difference in the operation is the use of the channel string in the scan
list to specify the channels on specific SCXI modules you want to
acquire. All other parameters of the DAQ Add-In operate the same.
SCXI Operating Modes
You can operate SCXI modules in two different modes-multiplexed
and parallel. In the multiplexed mode, all analog input channels for
each SCXI module are multiplexed (routed) onto one input channel of