Rockwell Automation T3441A User Manual

ICS Regent

®

PD-6015

DC Digital Output Module

24 VDC

(T3441A)

Issue 1,

The DC digital output module provides cont
output loads. One type of module is available to interface to
outputs powered from a nominal 24 VDC field power supply.
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.

rol of 16 user

March, 06

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.

Industrial Control Services

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DC Digital Output Module

(T3441A)

Module Operation

A block diagram of a typical 24 VDC digital 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 operation). The voted result is
then

passed to the I/O bus interface logic.

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Figure 1. Block Diagram of 24 VDC Digital Output Module.

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.

Industrial Control Services

(T3441A)

DC Digital Output Module

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

Optical isolation between the module’s logic and field circuits
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 ou

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.

— protecting the output

tput wiring and field devices.

e field device is

Each type of module has a unique ide
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
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.

Fuses are
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.

continually checked for continuity. Field power

ntification code that is

PD-6015

Mar-06

3

Note:

DC Digital Output Module

(T3441A)

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 ACTIVE indicator turns off.

Shutdown Indicator

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
always be off (see page 8, Fault Mode Jumper).

indicator will

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 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 lit when the
output FET is energized to turn on the load.

Blown Fuse Indicators

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 Maintena
replacement instructions.

nce, page 12, for fuse

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Industrial Control Services

(T3441A)

DC Digital Output Module

PD-6015

Mar-06

Figure 2. 24 VDC Digital Output Module.

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