DESCRIPTION AND OPERATION
LOGIC POWER
2 - 4
I-E96-309A
®
module reads the status byte and compares it to an expected
value. If a mismatch occurs, it flags the error and marks the
point as bad quality.
LOGIC POWER
Logic power (+5 VDC) drives the DSM circuits. It connects
through the top 12-pin card edge connector (P1) shown in Fig-
ure
.
SLAVE EXPANDER BUS
The Infi 90 slave expander bus is a high speed synchronous
parallel bus. It provides a communication path between MFP
or LMM master modules and slave modules. The master mod-
ule provides the control functions and the DSM module pro-
vides inputs/outputs to the master module. The P2 card edge
connector of the DSM and master module connect to the bus.
The slave expander bus is twelve parallel signal lines located
on the Module Mounting Unit (MMU) backplane. A 12-position
dipshunt placed in a connection socket on the MMU backplane
connects the bus between the master and slave modules. Cable
assemblies can extend the bus to six MMUs.
A master module and its slaves form an individual subsystem
within a Process Control Unit (PCU). The slave expander bus
between master/slave subsystems must be separated. Leaving
a dipshunt socket empty or not connecting the MMUs with
cables separates them.
UNIVERSAL SLAVE EXPANDER BUS INTERFACE
The DSM uses a semi-custom gate array to perform the slave
expander bus interface function. All the control logic and com-
munication protocol are built into an integrated circuit (IC).
This IC 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.
NOTE: Address information (a single 6-bit module address from the
master) enters the DSM through the slave expander bus interface
only if the addresses match. Refer to the Installation section for
more information.