Chapter 9 SCXI—Signal Conditioning

Multiplexed Mode for Analog Output Modules

Because LabVIEW communicates with the multiplexed modules over the SCXIbus backplane, you need to cable only one multiplexed module in each chassis to a DAQ device to communicate with any multiplexed modules in the chassis.

Multiplexed Mode for Digital and Relay Modules

Multiplexed mode is referred to as serial mode in the digital and relay module hardware manuals. When you operate your digital or relay module in multiplexed mode, LabVIEW communicates the module channel states serially over the SCXIbus backplane.

Parallel Mode for Analog Input Modules

When an analog input module operates in parallel mode, the module sends each of its channels directly to a separate analog input channel of the DAQ device cabled to the module. You cannot multiplex parallel outputs of a module on the SCXIbus. You must cable a DAQ device directly to a module in parallel mode to access its input channels. In this configuration, the number of channels available on the DAQ device limits the total number of analog input channels. In some cases, however, you can cable more than one DAQ device to separate modules in an SCXI chassis. For example, you can use two AT-MIO-16E-2 devices operating in parallel mode and cable each one to a separate SCXI-1120 module in the chassis.

By default, when a module operates in parallel mode, the module sends its channel 0 output to differential analog input channel 0 of the DAQ device, the channel 1 output to analog input channel 1 of the DAQ device, and

so on.

When you use the analog input VIs, specify the correct onboard channel for each parallel SCXI channel. If you are using a range of SCXI channels, LabVIEW assumes the onboard channel numbers match the SCXI channel numbers.

Parallel Mode for the SCXI-1200 (Windows)

In parallel mode, the SCXI-1200 reads only its own analog input channels. The SCXI-1200 does not have access to the analog bus on the SCXI backplane in parallel mode. You should use parallel mode if you are not using other SCXI analog input modules in the chassis with the SCXI-1200.