ICS TRIPLEX T8310 Trusted TMR Expander Processor

Trusted TMR Expander Processor 

Product Overview 

The Trusted® TMR Expander Processor Module resides in the processor slots of the Trusted 

Expander Chassis and provides the ‘slave’ interface between the Expander Bus and the Expander 

Chassis Backplane. The Expander Bus allows multiple chassis systems to be implemented using 

Unshielded Twisted Pair (UTP) cable connections whilst maintaining the fault tolerant, high 

bandwidth Inter-Module Bus (IMB) capabilities. 

The Module provides fault containment for the Expander Bus, the Module itself and the Expander 

Chassis, ensuring that the effects of these potential faults are localised and system availability 

maximised. The Module is fault tolerant with HIFT TMR architecture. Comprehensive diagnostics, 

monitoring and testing provide rapid fault identification. Hot-standby and module spare 

configurations are supported, allowing automatic and manual repair strategies 

Features: 

• Triple Modular Redundant (TMR), fault tolerant (3-2-0) operation. 

• Hardware Implemented Fault Tolerant (HIFT) architecture. 

• Dedicated hardware and software test regimes which provide very fast fault recognition and 

response times. 

• Automatic fault handling without nuisance alarming. 

• Hot replacement. 

• Front Panel indicators that show module health and status.

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 

cannot propagate between them. 

Power Distribution 

The TMR Expander Processor Module derives its internal voltages from dual redundant +24 

Vdc power supplied via the module connector from the Trusted Expander Chassis Backplane. 

Each FCR derives the required supplies independently.