Table 3-1. Scxibus Equivalents For The Rear Signal Connector - National Instruments SCXI-1121 User Manual

Pin
A24
B24
C24
All other pins are not connected.
© National Instruments Corporation
Signal Name
TRIG0
SS*
SCANCON
MOSI, MISO, SPICLK, and SS* form a synchronous communication link
that conforms with SPI using an idle-high clock and second-edge data
latching. D*/A, INTR*, and RESET* are additional control signals.
When the module is being used in an SCXI-1000 or SCXI-1001 chassis, the
data acquisition board, via the module rear signal connector, must tap into
the open-collector backplane signal lines as a master to write to the module.
The signal connections from the rear signal connector to the backplane are
shown in Table 3-1.

Table 3-1. SCXIbus Equivalents for the Rear Signal Connector

Rear Signal
Connector Signal
SERDATIN
DAQD*/A
SLOT0SEL*
SERCLK
SERDATOUT
The SCXI-1121 module converts the data acquisition board signals to
open-collector signals on the backplane of the SCXI chassis. In order for
the data acquisition board to talk to a slot, the board must first assert the SS*
for that slot. This is done by asserting INTR* low, writing a 16-bit number
over MOSI corresponding to the desired slot (and chassis if an SCXI-1001
Description
TRIG0—General-purpose trigger line used by the
SCXI-1121 to send SCANCLK to other modules
or receive SCANCLK from other modules. Open
collector. I/O.
Slot Select—When low, enables module
communications over the SCXIbus. Totem pole.
Input.
Scanning Control—Combination output enable
and reload signal for scanning operations. Totem
pole. Input.
SCXIbus Equivalent
MOSI
D*/A
INTR* Jumper W44 must be set to position 1
SPICLK
MISO Jumper W38 must be set to position 1
3-5
Chapter 3 Theory of Operation
SCXI-1121 User Manual