Chapter 2
Connecting Signals
©
National Instruments Corporation
2-5
In multiplexed mode, the AI 0 signal pair is used for sending all
24 channels of the SCXI-1521/B, and analog signals from other modules,
to the connected E/M Series DAQ device. If the module is cabled directly
to the E/M Series DAQ device, the other analog channels of the E/M Series
DAQ device are unavailable for general-purpose analog input because they
are connected to active signals on the SCXI-1521/B amplifier.
Table 2-3 lists the communication signals between the E/M Series DAQ
device and the SCXI system. If the E/M Series DAQ device is connected to
the SCXI-1521/B, these digital lines are unavailable for general-purpose
digital I/O.
Table 2-3.
SCXI-1521/B Communication Signals
Pin
SCXI Signal
Name
NI-DAQmx
Device Signal
Name
Direction
Description
24, 33
DIG GND
D GND
—
Digital ground—These pins supply
the reference for E/M Series DAQ
device digital signals and are
connected 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
Slot 0.
26
SER DAT
OUT
P0.4
Output
Serial data out—This signal taps
into the SCXIbus MISO line to
accept serial output data from a
module.
27
DAQ D*/A
P0.1
Input
Board data/address line—This
signal taps into the SCXIbus D*/A
line to indicate to the module
whether the incoming serial stream
is data or address information.
29
SLOT 0 SEL*
P0.2
Input
Slot 0 select—This signal taps into
the SCXIbus INTR* line to indicate
whether the information on MOSI
is being sent to a module or Slot 0.
