Theory of Operation
Chapter 3
SCXI-1160 User Manual
3-4
© National Instruments Corporation
SCXIbus Connector Signal Descriptions
Pin
Signal Name
Description
A21, B21, C21,
CHSGND
Chassis Ground – Digital and analog 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-Select Register Slot 0. Open
collector. Output.
A20, B20, C20,
V-
Negative Analog Supply – -18.5 to -25 V.
D20
A22, B22, C22,
V+
Positive Analog Supply – +18.5 to +25 V.
D22
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
communication 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 write to the module. The signal connections from the rear signal connector to the backplane
are shown in Table 3-1.