Signal Connections
Chapter 3
SCXI-1122 User Manual
3-12
© National Instruments Corporation
In particular, when using differential input DAQ boards such as the MIO-16 boards, it is
preferable to leave jumper W1 in its factory setting or in position AB-R1 to avoid ground loops.
With DAQ boards that are configured for referenced single-ended (RSE) measurements, set
jumper W1 in position AB-R0 to connect the SCXI-1122 ground to the DAQ analog ground.
Pin 19 is the OUTREF pin; this pin is connected internally to the analog reference when jumper
W1 is in position AB-R2. Pins 3 and 4 are the analog output channel of the SCXI-1122. Pins 3
and 4 or MCH0
±
are a multiplexed output of the input channels and the temperature sensor
output. Notice that the temperature sensor is located on the terminal block.
Warning: The SCXI-1122 analog outputs are not overvoltage-protected. Applying external
voltages to these outputs can damage the SCXI-1122. National Instruments is
NOT
liable for any damages resulting from such signal connections.
Note: The SCXI-1122 analog outputs are short-circuit protected.
Digital I/O Signal Connections
Pins 24 through 27, 29, 33, 36, 37, 43, and 46 constitute the digital I/O lines of the rear signal
connector–the digital input signals, the digital output signals, and the digital timing signals.
The digital input signals are pins 24, 25, 27, 29, 33, and 37. The DAQ board uses these pins to
configure an SCXI module that is under DAQ board control. Each digital line emulates the
SCXIbus communication signals as follows:
•
Pin 25, SERDATIN, is equivalent to the SCXIbus MOSI serial data input line.
•
Pin 27, DAQD*/A, is equivalent to the SCXIbus D*/A line. It indicates to the module
whether the incoming serial stream on SERDATIN is data (DAQD*/A = 0), or address
(DAQD*/A = 1) information.
•
Pin 29, SLOT0SEL*, is equivalent to the SCXIbus INTR* line. It indicates whether the data
on the SERDATIN line is being sent to Slot 0 (SLOT0SEL* = 0) or to a module
(SLOT0SEL* = 1).
•
Pins 24 and 33 are the digital ground references for the DAQ board digital signals and are
tied to the module digital ground.
•
Pin 37, SERCLK, is equivalent to the SCXIbus SPICLK line and is used to clock the serial
data on the SERDATIN line into the module registers.
The digital output signal, pin 26, is SERDATOUT and is equivalent to SCXIbus MISO.
The SCXI-1122 digital input and output signals match the digital I/O lines of the MIO-16 boards.
When used with an SCXI-1341, SCXI-1342, or SCXI-1344 cable assembly, the SCXI-1122
signals match the digital lines of the Lab-NB/PC/PC+, the PC-LPM-16, and the Lab-LC boards,
respectively. Table 3-2 lists the equivalences. For more detailed information, consult your cable
installation guide.
