Programming instructions

Chapter 21 Common SCXI Applications
© National Instruments Corporation 21-11 LabVIEW Data Acquisition Basics Manual
and filter settings on the SCXI-1121 module with jumpers as well as in
your system’s configuration utility. For information on how to connect and
configure the RTD with the SCXI-1121 module, look at the
Getting Started
with SCXI
manual or the RTD application note mentioned previously.
The SC-2042 RTD is a signal conditioning device designed specifically for
RTD measurement and can be used as an alternative to SCXI modules. For
more information, refer to the National Instruments catalog.
You do not have to worry about cold-junction compensation with RTDs
as you do when measuring thermocouples. To build an application in
LabVIEW, you can use the Easy I/O analog input VIs. If you are measuring
multiple transducers on several different channels, you will need to scan
the necessary channels with little overhead. Because the Easy I/O VIs
reconfigure your SCXI module every time your application performs an
acquisition, it is recommended that you use the Intermediate analog
input VIs.
Using the DAQ Channel Wizard to configure your channels can simplify
the programming needed to measure your signal, as shown in Figure 21-5.
LabVIEW configures the hardware with appropriate input limits and gain,
measures the RTD, and scales the measurement for you. Enter the name of
your configured channel in the
channels
input parameter. The acquired
data is in the physical units you specify in the DAQ Channel Wizard.
Figure 21-5.
Measuring Temperature Using Information from the DAQ Channel Wizard