Rockwell Automation T8424 Trusted TMR 120Vac Digital Input Module - Manual (Page 8)

Trusted TM Module T8424
Issue 8 Sep 11 PD-T8424 8
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 Trusted
TM TMR 120VAC Digital Input, each FIU contains an individual analogue to digital (A/D)
converter for each of the 40 field inputs.
The FIU isolates the power received from the HIU for supplying the analogue measurement and digital
interface circuitry. 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, 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 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:
1.4. Front Panel Unit (FPU)
The Front Panel Unit (FPU) comprises a Front Panel Termination Unit (FPTU) and a Front Panel
Display Unit (FPDU). The overall FPU contains the necessary connectors, switches, logic, and LED
indicators for the front panel. For every type of Trusted
TM I/O module, the FPU contains the Slice
Healthy, Active/Standby and Educated indicators (LEDs), and the module removal switches.
Additional bicolour 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.
• 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.
• Redundant power sharing of dual 24V dc chassis supply voltage and power regulation for
logic power to HIU circuitry.
• 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