Chapter 3
Connecting the Signals
SCXI-1141/1142/1143 User Manual
3-10
ni.com
The signals on the rear signal connector are classified as analog output,
digital I/O, or timing I/O signals.
Analog Output Signal Connections
Pins 3 through 17 of the rear signal connector are analog output signal pins.
Pin 3 is the main output, and pin 4 is its reference signal. All eight channels
are multiplexed onto this output when the module is software-configured
for multiplexed scanning mode. In parallel scanning mode, the output of
pin 3 is the output of one selected channel. Channel 0 is the power-up and
reset default. When scanning multiple modules, you can also connect this
output to the SCXIbus analog bus and the analog bus will drive this output.
Pins 5, 7, 9, 11, 13, 15, and 17 are direct outputs from channels 1 through 7,
respectively. In parallel mode, all eight channels are available
simultaneously at the rear connector. Pins 6, 8, 10, 12, 14, 16, and 18 are
the reference signals for outputs 1 through 7.
Caution
The SCXI-1141/1142/1143 module analog outputs are not overvoltage protected,
although they are short-circuit protected. Applying external voltage to these outputs can
result in damage to the SCXI-1141/1142/1143 module. NI is
not
liable for any damage
resulting from such signal connections.
Digital I/O Signal Connections
Pins 24 through 27, 29, 33, 36, 37, and 43 constitute the digital I/O lines of
the rear signal connector. Each of these pins is in one of three
categories—digital input signals, digital output signals, and timing signals.
Pins 24 and 33 are the digital ground reference for all of the DAQ device
digital signals and are tied to the module digital ground.
26
SERDATOUT
Serial data out—this signal taps into the SCXIbus MISO line
to accept serial output data from a module.
36
SCANCLK
Scan clock—the signal at this pin indicates to the
SCXI-1141/1142/1143 module that a sample has been taken
by the DAQ device and causes the SCXI-1141/1142/1143
modules to change channels.
Notes:
All other pins are not connected.
An * means the signal is asserted low.
Pin
Signal Name
Description
