Chapter 3
Theory of Operation
© National Instruments Corporation
3-3
SCXI-1162 User Manual
SCXIbus Connector Signal Descriptions
Pin
Signal Name
Description
A21, B21, C21,
CHSGND
Chassis Ground – Digital ground reference.
D21
A19
RESET*
Reset – When pulled low, reinitializes the module to
its power-up state. Totem pole. Input.
B19
MISO
Master-In-Slave-Out – Transmits data from the
module to the SCXIbus. Open collector. I/O.
C19
D*/A
Data/Address – Indicates to the module whether
address information or data information is being
sent to the module on MOSI. Open collector. I/O.
D19
INTR*
Interrupt – Active low. Causes data that is on
MOSI to be written to the Slot 0 Slot-Select
Register. Open collector. Output.
A23, D23
+5 V
+5 VDC Source – Digital power supply.
B23
SPICLK
Serial Peripheral Interface (SPI) Clock – Clocks the
serial data on the MOSI and MISO lines. Open
collector. I/O.
C23
MOSI
Master-Out-Slave-In – Transmits data from the
SCXIbus to the module. Open collector. I/O.
B24
SS*
Slot Select – When low, enables module
communications over the SCXIbus. Totem pole.
Input.
All other pins are not connected.
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 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 communicate on the SCXIbus. The signal connections from the rear signal connector to the
backplane are shown in Table 3-1.
