Rockwell Automation T8423 Trusted TMR 35 - 120 Vdc Digital Input Module - Manual (Page 10)

Trusted
TM
Module T8423
Issue 15 Apr 10 PD-T8423 10
1.2. Field Interface Unit (FIU)
The Field Interface Unit (FIU) is the section of the module that contains the specific circuits necessary
to interface to the particular types of field I/O signals. Each module has three FIUs, one per slice. For
the TMR 120V dc Digital Input module, the FIU contains an individual analogue to digital (A/D)
converter for each of the 40 field inputs.
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 serial link connects
each FIU to one of the HIU slices.
The FIU also measures a range of on-board “house-keeping” 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, board temperature, and condensation.
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 Trusted
TM 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 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.
• Optically isolated serial data interface to the FIU slices.
• Redundant power sharing of dual 24V dc 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.