Host Interface Unit (Hiu) - Rockwell Automation ICSTT-RM280N-EN-P Manual

Trusted TMR 24Vdc Digital Output Module – 40 Channel
The FIU receives isolated power from the HIU for logic. The FIU provides additional power
conditioning for the operational voltages required by the FIU circuitry. An isolated 6.25
Mbit/sec serial link connects each FIU to one of the HIU slices.
The FIU also measures a range of on-board "housekeeping" signals that assist in monitoring
the performance and operating conditions of the Module. These signals include power
supply voltages, current consumption, on-board reference voltages and board temperature.

1.3. 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 co-ordination 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.
• On-board housekeeping, which monitors reference voltages, current consumption
and board temperature.
Rockwell Automation Publication ICSTT-RM280N-EN-P Issue 14
1. Description
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