Rockwell Automation T7441A User Manual

ICS Regent+Plus

®

PD-7015

DC Digital Output Module

24 VDC

(T7441A)

Issue 1,

The DC digital output module provides control of 16 user
output loads. One type of module is available to interface to
outputs powered from a nominal 24 VDC field power su
Each module's triplicated I/O Safetybus interface ensures that
no Regent system failure can incorrectly apply power to an
output, and that no failure in the module can affect the
operation of the Regent system or other I/O modules in the
system.

March, 06

pply.

Features

·

Sixteen output circuits, configured as two isolated groups of
eight circuits each.

·

Hot-replaceable.

·

Automatic self-testing of triplicated I/O Safetybus circuits and
many simplex logic circuits.

·

2 amp output circuits.

·

Individual front panel indicators on each module show
active/fault, shutdown, blown fuse, and output on/off status
(field side).

·

2500 volt minimum electrical isolation between field and logic
circuits.

·

TÜV certified, Risk Class 5, non-interfering.

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1

DC Digital Output Module

(T7441A)

Module Operation

A block diagram of a typical 24 VDC digit
shown in Figure 1.

The processor modules send triplicated write data commands
to the output module over the I/O Safetybus. The processors’
addressing data and data write commands are voted by the
module (preventing I/O Safetybus failures upstream from the
module from affecting module operation). The voted result is
then passed to the I/O bus interface logic.

al output module is

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Figure 1. Block Diagram of 24 VDC Digital Output Mo

The voted output data from the I/O bus interface logic is then
used to drive the output circuits. Power MOSFETs are used
on the outputs to convert the logic level output drive signals
to switch 24 VDC power to load devices. These output circuits
provide a very low on state voltage drop and low off state
leakage.

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dule.

(T7441A)

When the output is logically turned on, the field device is
energized, and when the output is logically turned off, the
field device is de-energized.

DC Digital Output Module

Optical isolation between the module’s l
provides logic-to-field isolation
module from field signal over voltages, transients, and other
electrical disturbances. It also provides a safety barrier
between the primary field voltages and user accessible
circuits.

Each output is individually fused to protect the circuits from
short circuit conditions in output wiring and field devices.

Testing and Diagnostics

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 t

o address that module and its points specifically. If a
module is removed, or is replaced with a module of a different
type, the processor modules will indicate an I/O module error.

— protecting the output

ogic and field circuits

PD-7015

Mar-06

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.

Fuses are continually checked for continuity. Field power
must be connected to the output module in order for it to
detect a blown fuse.

Front Panel Indicators

The

24 VDC digital output module is shown in Figure 2. The
front panel contains active and fault status indicators, a
shutdown indicator, blown fuse indicators (one per output
group) and an output status indicator for each output circuit.

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Note:

DC Digital Output Module

(T7441A)

Active and Fault Status Indicators

These green and red LEDs indicate the overall health of the
module. During normal operation, the green ACTIVE
indicator flashes at the controller’s scan rate. If a module
fault is detected the red FAULT indicator
green ACTIVE indicator turns off.

Shutdown Indicator

turns on and the

Upon loss of communications with the controller, output
modules enter either a shutdown or hold fault mode. If the I/O
unit is set to shutdown, the red SHUTDOWN indicator will
turn on when communications with the controller are lost. If
the I/O unit is set to hold, the SHUTDOWN indicator will
always be off (see page 7, Fault Mode Jumper).

When the module is installed in the I/O chassis or when logic
power (fro

m the I/O power supply modules) is first applied to
the module, it will be in the shutdown mode until the first
output scan, regardless of the fault mode jumper settings.
Also, removing two I/O transceiver modules, two I/O power
supply modules, or two power legs will cause the module to be
in the shutdown mode.

Output Status Indicators

The output status indicators are yellow LEDs, located on the
field side of the output. There are 16 output status indicators,
— one for each output. These indicators are l
output FET is energized to turn on the load.

Blown Fuse Indicators

it when the

The red BLOWN FUSE indicators turn on when one of the
fuses in the corresponding output group opens. A blown fuse
will also cause the module’s FAULT indicator to turn on.

Field power must be connected to the module for it to detect a
blown fuse. Refer to Maintenance, page 11, for fuse
replacement instructions.

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