Chapter 4
Theory of Operation
SCXI-1141/1142/1143 User Manual
4-18
ni.com
Rear Connector Analog Outputs
The connector signals AOUT<1..7> and AGND are the outputs of channels
1 through 7. You can configure the OUTPUT and OUTPUT REF signals
as any channel (0 through 7) of the SCXI-1141/1142/1143 module or as the
output of a channel passed along the SCXIbus from any other module in the
chassis. Thus, the SCXI-1141/1142/1143 modules can present its outputs
in both parallel and multiplexed modes.
Multiplexed Mode (Recommended)
In multiplexed mode, the output signals for channels 1 through 7 are sent
to the rear signal connector but are usually ignored. All samples from the
module are from the OUTPUT signal of the rear signal connector,
which you can configure as the output of any channel of the
SCXI-1141/1142/1143 module or as the output of any other module in
multiplexed mode that is sending its output onto the SCXIbus. You can also
configure the SCXI-1141/1142/1143 module to send any one of its outputs
to the SCXIbus. Thus, in multiplexed mode only, one module in a chassis
needs to be connected to a DAQ device. You can pass signals from the
other modules to the DAQ device through the SCXIbus.
Multiplexed mode is also useful for performing scanning operations with
the SCXI-1141/1142/1143 module. E Series MIO devices and the
SCXI-1200 support scanning. The SCXI chassis is programmed with a
module scan list that dynamically controls which module sends its output
to the SCXIbus during a scan. You can specify this list to scan the modules
in any order, with an arbitrary number of channels for each module entry in
the list. However, you must scan the channels on the SCXI-1141/1142/1143
module in consecutive, ascending order. After channel 7 is scanned, the
module wraps back to channel 0 and continues. You can program the
SCXI-1141/1142/1143 module to start scans with any channel.
