Rockwell Automation T743x User Manual

ICS Regent+Plus

PD-7037

RTD Input Equipment

Input Module, Mux, Termination Panel and Cable

(T7432-IM, T7432-Mux, T7432-TP and T7432-CA)

Issue 1,

The RTD input equipment includes a RTD input module (T7432-IM), a RTD input multiplexer (T7432-MUX) termination panel (T7432-TP), and a RTD termination cable (T7432-CA). This equipment provides terminations and temperature conversion for as many as 16 RTD inputs, arranged in 2 groups of eight inputs.

Features

March, 06

, a RTD

Sixteen inputs for 100W platinum RTDs.

Configuration options: RTD type:

Input Leads: Units: Resolution: Noise Filter:

Complete linearization and automatic calibration.

Remote terminations up to 50 cable feet from I/O chas

Individual front panel indicators on each module show active, fault and MUX fault status.

2500 volt isolation between Input Module

Hot-replaceable input module and Mux.

Extensive fault diagnostics.

TÜV certified for safety, Risk Class 5.

The input module plugs into an I/O chassis slot and receives data from the RTD input multiplexer (or Mux). The RTD input multiplexer plugs into the termination panel and provides low level signal conditioning, multiplexing, and

American (" = 0.00392 S/S/°C) European (" = 0.00385 S/S/°C) 2, 3 or 4-wire Degrees F or degrees C Units or tenths 50 Hz, 60Hz rejection

and Mux.

sis.

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RTD Input Equipment

analog-to-digital conversion. The termination panel can be locat

Each module’s triplicated I/O Safetybus interface ensures that no failure in the module can affect the operation of the Regent system or other I/O modules in the system. Extensive fault detection and annunciation of critical redundant circuits help prevent the controllers from receiving erroneous data from a faulty input module. The fault tolerant boundary may be extended by using three input modules and three multiplexers. A single RTD can be wired to a single RTD termination panel which contains three RTD multiplexers for fault tolerance. The fault tolerant boundary may be further extended into the process by wiring three separate RTDs, all measuring the same process parameter, to separate termination panels, multiplexers and input modules. In either triplicated configuration, a failed module or multiplexer can be removed and replaced without interrupting the input signals.

(T7432)

ed as far as 50 cable feet from the I/O chassis.

Module Operation

A simplified block diagram of the RTD input equipment is shown i

Two, three, or four-wire RTDs are terminated at the termination panel. The termination panel routes the RTD signals to the Mux for multiplexing, signal conditioning, and A to termination panel for fault tolerance.

The termination cable connects to the termination panel to carry RTD data between the input Mux’s and RTD input modules. A DC-to-DC converter on the input module shares three power legs from the I/O backplane power and provides isolated power to the Mux over the termination cable. The Mux transmits digitized serial RTD data back to the input module. The maximum allowable cable length is 50 feet.

Sixteen, replaceable current sources on the term panel provide power to the individual RTDs. These current sources receive and share power from the one, two or three Mux’s installed in the termination panel.

n Figure 1.

D conversion. Up to three Mux’s can be installed in the

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RTD Input Equipment

(T7432)

Figure 1. Block Diagram of the RTD Input Equipment.

The Serial data received from the Mux is optically coupled at the input module to provide electrical isolation. The input module's 68000-based microcomputer processes the RTD data. This microcomputer’s functions include:

Noise filtering

Automatic calibration

Temperature conversion and linearization

RTD lead-wire compensation

Diagnostics

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

PD-7037

Mar-06

RTD Input Equipment

After receiving the voted data read request, the microcomputer transmits the conditioned temperature data to the Safetybus interface. This interface places the voted temperature data onto the triplicated Safetybus bus drivers. Each of the three bus drivers is independently powered and controlled (by the I/O transceiver modules) — preventing failures in a single driver from propagating to the other two I/O busses. The bus drivers then transmit the data via the backplane I/O Safetybus to the I/O transceiver modules which, in turn, transmit the data to the processors.

The RTD input data is packaged as a 16-bit word for each input. The format of each word is shown in Fi most significant bit in the word is used as an alarm bit to indicate an out-of-range RTD input signal. The remaining 15 bits contain signed 15-bit integer data representing the temperature in degrees C or F and in units or tenths of degrees, as configured by jumper settings on the Mux.

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gure 2. The

Figure 2. RTD Input Data Format.

Testing and Diagnostics

Input 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 in

stalled in each I/O chassis slot and

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RTD Input Equipment

(T7432)

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.

Multiplexer Testing

The serial communications link to the RTD Mux is continuously monitored. Additionally the data receiv

ed from the Mux is checked for proper data format, parity and numeric range reasonableness. The precision voltage references on the multiplexer are also checked to verify that the power to the Mux is present and that the voltage references are within tolerance.

Input Module Front Panel Indicators

Figure 3 shows the physical features of the RTD input module. The front panel of each module contains status indicators to display the operational status of the input module and multiplexer.

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 occurs the red FAULT indicator turns on and the green ACTIVE indicator turns off.

PD-7037

Mar-06

MUX Fault Indicator

The red MUX FAULT indicator turns on when any of the following fault conditions are detected:

No data received from the Mux.

Corrupted data from the Mux.

Unreasonable data values from the Mux.

Failure of the DC-to-DC converter supplying power to the termination panel or the receiver circuitry can also result in a MUX fault. Both of these faults are input module faults.

RTD Input Equipment

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Figure 3. RTD Input Module.

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RTD Input Equipment

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Termination Panel and Multiplexer

Figure 4 shows the physical features of the RTD termination panel and multiplexer. The multiplexer plugs into the termination panel and is secured in place with two thumb screws located at each end of the multiplexer. Up to three multiplexers can be installed in a single termination panel. Each multiplexer interfaces to a separate RTD input module installed in an I/O Chassis.

Sixteen current sources are installed on the termination panel to source current to each RTD. The current sources are powered from the installed multiplexers and share power when multiple multiplexers are installed.

Termination cables plug into the DB-9 connectors located to the right of the three multiplexers. Each cable interfaces one multiplexer to its associated input module installed in an I/O chassis.

RTD inputs are wired to the terminal blocks located along the bottom of the termination panel. Each of the four terminal blocks has screw terminals for 4 RTD inputs. Four screw terminals are provided for each RTD input. Two additional ground terminals on each terminal block are provided to connect RTD cable shie

ld wires if desired.

PD-7037

Mar-06

RTD Multiplexer Indicators

Each RTD multiplexer has status indicators for power supply voltages, and transmit data. When positive and negative supply voltages are present at the termination panel, the + V, and – V indicators are on. The TX indicator is on when the Mux is transmitting data to the input module. Normally, all these green indicators should be on.

RTD Input Equipment

(T7432)

Figure 4. RTD Termination Panel and Multiplexer.

Application

Simplex Configuration

A single RTD input module and multiplexer provide a suitable interface to non-critical input signals. Although many of the circuits in the RTD input module and multiplexer are automatically tested and annunciated, some logic circuits and field-side sensing circuits are simplex and non-tested. This simplex input configuration is illustrated in Figure 5.

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