National Instruments 1141, 1142, 1143, SCXI - page 23

Chapter 2 Connecting Signals
© National Instruments Corporation 2-9 SCXI-1141/1142/1143 User Manual
In parallel output mode, channel 0 is selected at the output multiplexer and
is connected to AI 0. The seven other channels are directly connected to
AI1 through AI 7, respectively, on the rear connector.
In multiplexed mode, the AI 0 signal pair is used for sending all eight
channels of the SCXI-1141/1142/1143, and analog signals from other
modules, to the connected E/M Series DAQ device. If the module is cabled
directly to the DAQ device, the other analog channels of the DAQ device
are unavailable for general-purpose analog input because they are
connected to the SCXI-1141/1142/1143 amplifier outputs. This means that
connecting an SCXI-1180 module to the 50-pin breakout connector of the
SCXI-1349, or other cable adapter assembly, may cause interference and
incorrect measurements when the DAQ device is cabled to the
SCXI-1141/1142/1143.
The communication signals between the DAQ device and the SCXI system
are listed in Table2-3. If the DAQ device is connected to the
SCXI-1141/1142/1143, these digital lines are unavailable for
general-purpose digital I/O.
Table 2-3. SCXI-1141/1142/1143 Rear Communication Signals
Pin
SCXI Signal
Name
NI-DAQmx
Device Signal
Name Direction Description
5, 7, 9,
11, 13,
15, 17
AI <1..7> N/A Output Analog outputs—these pins are the
outputs of channels 1 through 7,
regardless of the scanning mode.
6, 8,
10, 12,
14, 16,
18
A GND AI GND —Analog ground—these pins connect
to the module analog ground. They
are used as the reference points for
AI 1 + through AI 7 +.
24,
33
DIG GND D GND —Digital ground—these pins supply
the reference for E/M Series DAQ
device digital signals and connect to
the module digital ground.
25 SER DAT IN P0.0 Input Serial data in—this signal taps into
the SCXIbus MOSI line to send
serial input data to a module or
Slot0.