Digital i/o signal connections, Digital i/o signal connections -40 – National Instruments SCXI-1121 User Manual
Page 56
Chapter 2
Configuration and Installation
2-40
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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. They are divided into three categories—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 data
acquisition board uses these pins to configure an SCXI module that is under
data acquisition board control. Each digital line emulates the SCXIbus
communication signals as follows:
•
Pin 25 is SERDATIN and is equivalent to the SCXIbus MOSI serial
data input line.
•
Pin 27 is DAQD*/A and 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 is SLOT0SEL* and 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 data acquisition
board digital signals and are tied to the module digital ground.
•
Pin 37 is SERCLK and 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 is pin 26.
•
Pin 26 is SERDATOUT and is equivalent to SCXIbus MISO when
jumper W38 is in position 1.
The digital input and output signals of the SCXI-1121 match the digital I/O
lines of the MIO-16 board. When used with an SCXI-1341, SCXI-1342, or
SCXI-1344 cable assembly, the SCXI-1121 signals match the digital lines
of the Lab-NB/Lab-PC/Lab-PC+/Lab-LC boards and the PC-LPM-16
board, respectively. Table 2-16 lists the equivalences. For more
information, consult Appendix E,