Programming instructions

Chapter 14 SCXI Hardware
DAQ Hardware Overview Guide 14-2 www.ni.com
Please refer to the SCXI Modules and Compatible DAQ Devices section
later in this chapter for information about the functionality of each DAQ
device with each type of SCXI module.
SCXI Installation and Configuration
To install your SCXI system, follow the instructions in your SCXI
hardware manual. After you assemble your SCXI system, you must run
Measurement & Automation Explorer to enter your SCXI configuration;
NI-DAQ needs the configuration information to program your SCXI
system correctly. Measurement & Automation Explorer Online Help
contains instructions for entering your SCXI configuration.
SCXI Operating Modes
The way that NI-DAQ has access to the signals from the modules depends
on the operating modes of the modules. There are two basic operating
modes for SCXI modules—multiplexed and parallel. The operating mode
is a parameter that you enter in the configuration utility.
Note
It is recommended that you use the multiplexed mode.
Multiplexed Mode for Analog Input Modules
When an analog input module operates in multiplexed mode, all of its input
channels are multiplexed to one module output. When you cable a DAQ
device to a multiplexed analog input module, the DAQ device has access
to that module’s multiplexed output, as well as the outputs of all other
multiplexed modules in the chassis via the SCXIbus. The SCXI functions
route the multiplexed analog signals on the SCXIbus for you transparently.
So, if you operate all modules in the chassis in multiplexed mode, you only
need to cable one of the modules directly to the DAQ device.
The module you cable to the DAQ device must be an analog input module.
Only analog input modules can route the analog signal from the SCXI bus
to the DAQ device. You can use the SCXI-1345 cable assembly to connect
an MIO or AI device directly to an analog input module in a non-remote
SCXI configuration. You must use the SCXI-1341 cable assembly for a
Lab-PC+, PCI-1200, Lab-PC-1200, Lab-PC-1200AI or DAQCard-1200.
You cannot cable a DIO device to an analog input module. If you are using
multiple analog input modules in multiplexed mode, you only need to cable
one of the modules in each chassis to the DAQ device, or you can control
the modules using the SCXI-1200 DAQ module.