Rockwell Automation T3151 User Manual

ICS Regent

PD-6003

Real-Time Clock Communications Modules

RS232 Communications and Battery-Backed

Real-Time Clock

(T3151)

Issue 1,

Real-time clock communications modules provide a serial communications interface between the controller and e equipment. The module also provides battery-backed real time information to the controller and applications programs. Real-time clock communications modules are recommended for applications that perform sequence of events recording or process historian data collection.

March, 06

xternal

Features

•

Battery-backed real-time clock.

Date format: Month-day-year.

Time format: Hours:minutes:seconds:milliseconds.

One millisecond resolution.

Two serial ports per module.

Supports RS-232 standards.

Hot Replaceable.

Front panel indicators on each module show communi status and transmit/receive activity.

TÜV certified for safety, Risk Class 5.

Module Operation

Figure 1 shows a block diagram communications module.

cations

of the real-time clock

Industrial Control Services

Real-Time Clock Communications Modules

(T3151)

Each real-time clock communications module has a Z80 micro processor, a PROM containing all of the module’s executable software, static RAM containing program variables, the real

time clock, shared RAM for transferring information between the processor modules and the communications module’s microprocessor, and a dual-channel UART with RS-232 serial port interfaces. Both the clock and the static RAM are battery-backed. If the system is powered down the batter

y continues to keep the clock running. The microprocessor reads the time, checks it for consistency, and then transfers it to the shared RAM where it can be read by the processor modules.

Each communications module receives power from all three of the processor modules. A power-sharing circuit in each of the communications modules receives the power from the three processor modules and combines it through a diode OR power sharing circuit. This ensures that if one processor module's power supply fails, th

e communications module will continue to operate by drawing power from the two remaining power supplies, and the system's communications functions are maintained.

The Dual UART (universal asynchronous receiver/trans

mitter) buffers incoming and outgoing communications characters. The triplicated processor modules interrupt once every millisecond to read characters from or write characters to the communications module.

Industrial Control Services

Real-Time Clock Communications Modules

(T3151)

PD-6003

Mar-06

Figure 1. Block Diagram of Real-Time Clock

Communications Module.

When the processor modules read characters from the communications module, the communications module sends characters through triplicated bus drivers to the processor Safetybus. The processor modules vote this triplicated data and perform communications processing. When the processor modules write data to the communications module, the triplicated data is voted by the communications modules and sent to the dual UART where it is then transmitted out the associated port.

The communications modules’ two serial ports operate independently and can both be configured differently to support a wide variety of functions including Regent R2

Real-Time Clock Communications Modules

(T3151)

protocol, Modbus protocol, ASCII output, and Guarded Peer Link communications. The

INTERPRET

application is used

to configure the appropriate port functions and specify baud rate, data format, parity, and node number.

Once each application program scan the processors modules read the real-time clock data from the module. The real-time clock informati

on is placed on the Safetybus from three independently controlled buffers, preventing failures in the real-time clock communications module from propagating into the system.

When the processor modules set the real-time clock, all real

time clock communications modules that are installed in the system are simultaneously set. After setting the real-time clocks, the processor modules read real-time clock values from the left-most installed communications module. If the left most real-time clock communication

s module is faulted, the

processor modules will then read real-time clock values from the next real-time clock communications module to the right.

Testing and Diagnostics

The modules triplicated Safetybus interface ensures that no failure in the module will effect the operation of the Regent system or other module. Extensive fault detection and annunciation of critical redundant circuits helps ensure that processors will not accept erroneous data from a faulty module.

Each type of communications module has a unique identification code that is read by the controller. This code lets the controller know what type of module is installed in each communications slot. If a module is removed and replaced with a module of a different type the processors will indicate a COMM error.

The processor modules perform background diagnostic checks on the module to test bus driver circuits and check the communications module ID codes. Clock values are checked for bad data. Communications message format, framing, checksum, the processor modules’ normal communications processing.

and other communications errors are checked by

Industrial Control Services

Real-Time Clock Communications Modules

(T3151)

Failures result in a COMM module error indication at the processor modules and an RTC/COMM error at the communications module.

Front Panel

Figure 2 shows the physical features of the real-time clock communications modules. The front panel of each module contains indicators showing overall module health, transmit and receive status, and backup battery power. In addition to the fro communications module has two DB-25 serial ports.

RTC/COMM Indicator

nt panel indicators, each real-time clock

This red and green LED pair indicates the overall health of the module. During normal operation the green LED is on. If a module fault occurs the red LED turns on and the green LED turns off.

Transmit/Receive Indicators

These green LEDs are connected directly to the RS-232 signal lines and flash while data are being transmitted or received. The TX LED flashes as data are sent from the module, an the RX LED flashes as data are received by the module.

PD-6003

Mar-06

Battery Status Indicator

This green LED is on when the battery is good and the module is installed in the controller chassis and is receiving power. This LED turns off if power is removed from the module, or if the battery runs low.

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