Rockwell Automation T7446L User Manual

ICS Regent+Plus

®

PD-7017

Relay Output Modules

Low Power and High Power

(T7446L and T7446H)

Issue 1,

Relay output modules provide control of eight user output
loads. Two types of relay output modules are available
providing dry contact relay clos
variety of AC and DC voltages to field loads. 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.

ure outputs for switching a

March, 06

Features

·

Eight isolated, dry contact relay outputs: four Form-C, and four
form-A or Form-B selectable.

·

Hot replaceable.

·

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

·

High power modules (T7446H) operate up to 250 VAC/125
VDC switching loads rated at 500 VA or 100 Watts.

·

Low power modules (T7446L) operate up to 125 VAC/VDC
switching loads rated at 60 VA or 30 Watts.

·

Individual front panel indicators on each module show active
and fault status, shutdo
side).

·

TÜV certified, Risk Class 5, non-interfering.

wn state, and output status (logic

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Relay Output Modules

(T7446L, H)

Module Operation

A block diagram of a typical relay output module is 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 operatio
then passed to the I/O bus interface logic.

n). The voted result is

2

Figure 1. Block Diagram of a Relay Output Module.

The voted output data from the I/O bus interface logic is then
used to drive the output circuits. Logic output drive signals
energize the coils of relays mounted on the printed circuit
board. Relay contacts provide dry-contact switching of load
devices.

When the output is logically turned on, the relay coil is
energized (closing the N.O.

contact), and when the output is

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(T7446L, H)

logically turned off, the relay coil is de-energized (closing the
N.C. contact).

The relay provides logic-to-field isolation between the
module’s logic and field circuits — protecting the output
module from field signal over voltages, transients, and other
electrical disturbances.

Both types of relay output module use UL 508 approved
relays.

Relay Output Modules

Testing and Diagnostics

Each module’s voter circuits are periodically tested by the
processor modules. Discrepant data are sent throug
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 m
module is removed, or is replaced with a module of a different
type, the processor modules will indicate an I/O module error.

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.

odule and its points specifically. If a

Front Panel Indicators

h one of

PD-7017

Mar-06

The relay output module is shown in Figure 2. The front
panel contains active and fault status indicators, a shutdown
indicator, and output status indicators for each output circuit.

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 turns on and the
green indicator turns off.

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Note:

Relay Output Modules

(T7446L, H)

Shutdown Indicator

Upon loss of communications with the controller, output
modules enter either a shutdown or hold fault mode. If the I/O
assembly is set to shutdown, the red SHUTDOWN indicator
will turn on when communications with the controller are lost.
If the I/O assembly is set to hold, the SHUTDOWN indicator
will always be off (see page 11, Fault Mode Jumper).

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

power (from 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 mo

dules, 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
logic-side (coil) of the relay output. There are eight output
status indicators

— one for each output. These indicators are
lit when the output relay coil is energized, closing the
normally open contact.

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(T7446L, H)

Relay Output Modules

PD-7017

Mar-06

Figure 2. Relay Output Module.

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Relay Output Modules

(T7446L, H)

Application

Simplex Configuration

Relay o
critical output devices. These non-critical devices typically
include status alarms or other field devices that are not used
for primary safety shutdown purposes. Although much of the
circuitry on the relay output module is automatically tested,
some logic circuits and the field-side output switch are simplex
and non-tested. This simplex configuration is illustrated in
Figure 3. For safety-critical outputs requiring fail-safe
fault tolerant output configurations, Guarded digital output
modules should be used.

utput modules provide a suitable interface to non

-

or

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Figure 3. Simplex Relay Output Configuration.

Field Wiring

For field wiring details, refer to PD-7901 - I/O Termination
Assembly (ITA).

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