DESCRIPTION AND OPERATION
OUTPUT CIRCUIT CONNECTIONS
2 - 4
I-E96-310B
®
LED and is input to the module status buffer. A module reset
(remove and insert) clears the latch. Removing the module to
replace the fuse resets the fuse status.
The status buffer block provides module status information to
the control module. This information is output states, fuse sta-
tus, and module identification and status. The control module
reads this data through the I/O expander bus interface. Refer
to
for an explanation of the data.
OUTPUT CIRCUIT CONNECTIONS
The output signals connect to edge connector P3 of the DSO
module using a cable from a termination device. The IMDSO02
and IMDSO03 modules require that proper polarity be
observed when wiring DC field signals. Polarity of AC signals
does not affect switching (IMDSO01 module).
I/O EXPANDER BUS
The INFI 90 I/O expander bus is a high speed synchronous
parallel bus. It provides a communication path between control
modules and I/O modules. The control module provides the
control functions and the I/O module provides the I/O func-
tions. The P2 edge connector of the I/O and control modules
connects to the bus.
The I/O expander bus is 12 parallel signal lines located on the
module mounting unit backplane. A 12-position dipshunt
placed in a connection socket on the module mounting unit
backplane connects the bus between the control and I/O mod-
ules. Cable assemblies can extend the bus to additional mod-
ule mounting units within a cabinet.
A control module and its I/O modules form an individual sub-
system within a process control unit. The I/O expander bus
between subsystems must be separated. Leaving a dipshunt
socket empty or not connecting the module mounting units
with cables separates the subsystems.
UNIVERSAL I/O EXPANDER BUS INTERFACE
The DSO module uses a custom gate array to perform the I/O
expander bus interface function. All the control logic and com-
munication protocol are built into an integrated circuit. This
integrated circuit provides the following functions:
•
Address comparison and detection.
•
Function code latching and decoding.
•
Read strobe generation.
•
Data line filtering of bus signals.
•
On-board bus drivers.
