ICS TRIPLEX T8451 Trusted TMR 24 Vdc Digital Output Module – 40 Channel

in monitoring the performance and operating conditions of the Module.

These signals include power supply voltages, current consumption, onboard

reference voltages and board temperature.

Host Interface Unit (HIU)

The HIU is the point of access to the Inter-Module Bus (IMB) for the Module.

It also provides power distribution and local programmable processing

power. The HIU is the only section of the I/O Module to directly connect to the

IMB Backplane. The HIU is common to most high integrity I/O types and has

type dependent and product range common functions. Each HIU contains

three independent slices, commonly referred to as A, B, and C.

All interconnections between the three slices incorporate isolation to help

prevent any fault interaction between the slices. Each slice is considered a

Fault Containment Region (FCR), as a fault on one slice has no effect on the

operation of the other slices.

The HIU provides the following services common to the Modules in the

family:

• High-Speed Fault Tolerant Communications with the TMR Processor

via the IMB interface.

• FCR Interconnect Bus between slices to vote incoming IMB data and

distribute outgoing I/O Module data to the IMB.

• Galvanically isolated serial data interface to the FIU slices.

• Redundant power sharing of dual 24 Vdc chassis supply voltage and

power regulation for logic power to HIU circuitry.

• Magnetically isolated power to the FIU slices.

• Serial data interface to the FPU for Module status LEDs.

• SmartSlot link between Active and Standby Modules for coordination

during Module replacement.

• Digital Signal Processing to perform local data reduction and

self-diagnostics.

• Local memory resources for storing Module operation, configuration,

and field I/O data.

• Onboard housekeeping, which monitors reference voltages, current

consumption and board temperature.

Front Panel Unit (FPU)

The Front Panel Unit (FPU) contains the necessary connectors, switches,

logic, and LED indicators for the Front Panel. For every type of Trusted I/O

Module, the FPU contains the Slice Healthy, Active/Standby, the Educated

LED indicators, and the Module removal switches. Additional bicolor LEDs

provide status indication for the individual I/O signals. Serial data interfaces

connect the FPU to each of the HIU slices to control the LED status indicators

and monitor the Module removal switches.