Rockwell Automation T3491 User Manual
ICS Regent
®
PD-6035
Multiplexed I/O Modules
(T3491)
Issue 1,
Multiplexed I/O modules provide two RS-422 serial port
interfaces between the Regent system and ICS’s remote
multiplexed I/O Unit (MIU) equipment, providing an
economical interface to digital inputs and outputs. MIU
equipment is often used for matrix and mimic displays in
safety and fire and gas systems or low cost, remote simplex
input and outputs.
March, 06
Features
•
Occupies one slot in the I/O chassis.
•
Two isolated RS-422 serial ports for remote multiplexed I/O.
•
Supports up to 512 digital inputs and 256 digital outputs of
remote MIU equipment.
·
Individual front panel indicators on each module show module
active and fault status; and transmit, receive and fault status
for each port.
•
Serial ports can be used in simplex or duplex modes (with
2oo2 testing in dual mode).
·
1000 volt minimum electrical isolation between serial ports
and between serial and logic circuits.
·
TÜV certified, Risk Class 5, non-interfering.
Multiplexed I/O mo
remote MIU equipment up to 4000 feet (1220 meters) away at
19200 baud. The two serial ports of the Mux I/O module can
be configured for simplex or duplex mode. In duplex mode,
2oo2 voting is performed on the I/O data.
dules support multi-drop connection to
Industrial Control Services
1
Multiplexed I/O Module (T3491)
The following MIU equipment may be interfaced to the
Multiplexed I/O Module
· MIU3201
· MIU3202
· MIU3204
A typical simplex application for multiplexed I/O is shown in
Figure 1.
Multiplexed I/O Processor Unit
Multiplexed Input Unit (64 point)
Multiplexed Output Unit (64 point)
Figure 1. Typical Multiplexed I/O Configuration.
Module Operation
A block diagram of the multiplexed I/O module is shown in
Figure 2.
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Industrial Control Services
Multiplexed I/O Module (T3491)
Figure 2. Block Diagram of Multiplexed I/O Module.
The Voter, FPGA and triple buffers provide
an interface to the
triplicated I/O Safetybus. The Mux I/O module receives
configuration data over the I/O Safetybus from the processor
modules. This information defines the types of Multiplexed
I/O Unit equipment connected to the Mux I/O module. The
information is stored in the module’s dual ported RAM
memory.
The RAM memory is arranged into four blocks. One block is
used to download the Mux I/O equipment configuration. The
second block is used for reporting fault conditions. A third
block is used f
or writing output data, and the fourth block is
used for reading input data. The on-board microprocessor uses
this information to read and write I/O data via the two serial
ports.
Testing and Diagnostics
PD-6035
Mar-06
Comprehensive testing and diagnostics are used to determine
correct operation to the Mux I/O Module and connected MIU
equipment.
3
Multiplexed I/O Module (T3491)
Standard Module Testing
Each module’s voter circuits are periodically tested by the
processor modules. Discrepant data are sent through one of
three legs of the I/O Safetybus to
determine whether the
module’s voter is able to outvote the incorrect data. A failure
to return the correct majority-voted result to the processors
produces an I/O module error indication at the processor
modules and a module fault indication at the I/O module.
Each type of module has a unique identification code that is
read by the controller. This code lets the controller know
which type of module is installed in each I/O chassis slot and
how to address that module and its points specifically. If a
mod
ule is removed, or is replaced with a module of a different
type, the processor modules will indicate I/O module errors.
Loopback logic tests periodically write data to the module and
then read it back to determine whether the module’s I/O bus
interface logic is functioning correctly.
Multiplexed I/O Module Testing
Additional tests are periodically performed to verify the
correct operations of the microprocessor, ROM, RAM and
serial interface to the remote MIU equipment. Detected
failures are reported back to the processor modules as either
fatal or non-fatal errors.
Fatal Errors
Fatal errors are reported when the diagnostics detect a failure
in the module’s electronics. For example, failures in the
microprocessor, RAM, or ROM are considered fatal errors. A
fatal error will result in a module fault indication.
Non-Fatal Errors
Non-fatal errors are reported when failures occur in
communications to the connected MIU equipment. These
failures would represent problems with the serial
communications cables, or the connected MIU processor.
These types of failures are indicated on the face of the module
as a Port fault.
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Industrial Control Services
Multiplexed I/O Module (T3491)
Front Panel Indicators
Figure 3 shows the physical features of the Mux I/O module.
The front panel of the module contains active, and fault status
indicators for the module as well as transmit, receive, and
communications fault status indicators for each port.
PD-6035
Mar-06
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Multiplexed I/O Module (T3491)
6
Figure 3. Multiplexed I/O Module.
Industrial Control Services
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