Chapter 3
Theory of Operation
3-4
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SCXIbus Connector Signal Descriptions
Pin
Signal Name
Description
A1, B1, C1, D1, A2,
D2,A3, B3, C3, D3, A4,
D4, A5, B5, C5, D5, A6, D6
GUARD
Guard—Shields and guards the analog bus lines
from noise.
B2
AB0+
Analog Bus 0+ —Positive analog bus 0 line. Used
to multiplex several modules to one analog signal.
C2
AB0–
Analog Bus 0– —Negative analog bus 0 line. Used
to multiplex several modules to one analog signal.
C13-C17, A21, B21, C21,
D21
CHSGND
Chassis Ground—Digital and analog ground
reference.
C18
RSVD
Reserved.
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 in
Slot 0. Open collector. Output.
A20, B20, C20, D20
V–
Negative Analog Supply— –18.5 to –25 V.
A22, B22, C22, D22
V+
Positive Analog Supply— +18.5 to +25 V.
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.
