Chapter 3
Signal Connections
© National Instruments Corporation
3-9
SCXI-1124 User Manual
Pin
Signal Name
Description
25
SERDATIN
Serial Data In–Taps into the SCXIbus MOSI line
to provide serial input data to a module or Slot 0.
26 or 47
SERDATOUT
Serial Data Out–Taps into the SCXIbus MISO line to
accept serial output data from a module. Pin 47 is for
DIO-type boards. Pin 26 is for MIO-type boards. Jumper
W2 selects the pin.
27
DAQD*/A
DAQ Board Data/Address Line–Taps into the SCXIbus
D*/A line to indicate to the module whether the incoming
serial stream is data or address information.
29
SLOT0SEL*
Slot 0 Select–Taps into the SCXIbus INTR* line to
indicate whether the information on MOSI is sent to a
module or to Slot 0.
31 or 37
SERCLK
Serial Clock–Taps into the SCXIbus SPICLK line to
clock the data on the MOSI and MISO lines. Pin 31 is for
DIO-type boards. Pin 37 is for MIO-type boards. Jumper
W3 selects the pin.
* Indicates active low.
All other pins are not connected.
See the Timing Requirements and Communication Protocol section in the SCXI-1124
Register-Level Programmer Manual for more detailed information on timing.
The signals on the rear signal connector are digital I/O signals. The following section describes
signal connection guidelines for each of these groups.
Digital I/O Signal Connections
Pins 24 through 27, 29, 31, 37, 47, and 50 are the digital I/O lines of the rear signal connector.
The digital input signals are pins 24 or 50, 25, 27, 29, and 31 or 37. The DAQ board uses these
pins to configure the SCXI module that the DAQ board controls.
Each digital line emulates the SCXIbus communication signals as follows:
•
Pin 24 or 50 is the digital ground reference for the DAQ board digital signals and is tied to
the module digital ground via jumper W4. Pins 24 and 50 are not tied together.
-
Pin 24 is for MIO-type boards when SCXI-1124 jumpers W2, W3, and W4 are in the
M position.
-
Pin 50 is for DIO-type boards when SCXI-1124 jumpers W2, W3, and W4 are in the
D position.
•
Pin 25, SERDATIN, is equivalent to the SCXIbus MOSI serial data input line.
