Rockwell-automation T71xx Regent+Plus Processor Modules 110 VAC, 220/2 User Manual download pdf (Page 3)

Processor Modules (T7110, 11, 12, 20, 21, and 22)

PD-7000 Sep-04 (Issue 1) 3

one processor module — allowing the other two modules to

continue operating — thus keeping the Regent on-line by virtue of

its majority two-out-of-three voting architecture.

Programs are stored in on-board battery-backed RAM. Program

instructions are fetched from each processor’s memory and

executed by the processors. Data from inputs are read from the

I/O modules in the I/O assembly. The main processor coordinates

the Regent’s activities and solves the application algorithms

programmed by the user. Outputs are driven by transmitting data

through the processor module’s I/O processor to the I/O assembly.

Communications between the main processor and the I/O

processor are maintained through shared RAM that is used as a

“mail box” for data transfers between the two processors.

All three processor modules operate independently in lock-step

synchronization with the other two modules, continuously

repeating a scan cycle (Figure 2).

Figure 2. The Regent’s Scan Cycle.

The main processors in each of the three processor modules run

programs and process communications synchronously, while the

I/O processors in each module read and write I/O synchronously.

During these synchronous operations, all instructions and data are

distributed across the Safetybus where automatic voting and fault

detection occur.

Main Processor

During each scan cycle, the main processor executes application

programs, reading inputs from the shared RAM and writing

outputs to the shared RAM.

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Rockwell-automation T71xx Regent+Plus Processor Modules 110 VAC, 220/2 User Manual Page 3