Rockwell Automation T8310 Trusted Expander Processor - Manual (Page 9)

Trusted
TM
Module T8310
Issue 12 Dec 06 PD-T8310 9
1.1. Overview
The TMR Expander Processor is a fault tolerant design based on TMR architecture arranged in a lock-
step configuration. Figure 1 shows, in simplified terms, the basic structure of the TMR Expander
Processor.
The module has three main fault containment regions (FCR A, B and C). Each of the main FCRs
contains interfaces to the Expander Bus and Inter-Module Bus (IMB), an active/standby interface to the
other TMR Expander Processor in the chassis, control logic, communications transceivers and power
supplies.
Communication between the module and the TMR Processor is via the TMR Expander Interface
Module and the triplicated Expander Bus. The Expander Bus is triplicated, point-to-point architecture.
Each channel of the Expander Bus comprises separate command and response media. Voting is
provided at the Expander Bus Interface to ensure that cable faults are tolerated, and the remainder of
the Expander Processor operates in a fully triplicated mode, even in case of cable faults occurring.
Communication between the module and the I/O modules in the Expander Chassis is via the IMB on
the backplane of the Expander Chassis. The IMB is identical to that within the Controller Chassis,
providing the same fault tolerant, high bandwidth communications between the interface modules and
the TMR Processor. As with the Expander Bus Interface all transactions are voted, localising faults to
the IMB should they occur.
A fourth FCR (FCR D) provides the non-critical monitoring and display functions and is also part of the
inter-FCR Byzantine voting structure.
Isolation is provided between FCRs wherever interfaces are required, to ensure that faults can not
propagate between them.
1.2. Power Distribution
The TMR Expander Processor Module derives its internal voltages from dual redundant +24V dc
power supplied via the module connector from the Trusted
TM Expander Chassis backplane. Each FCR
derives the required supplies independently.