Field Termination Unit (Ftu); Field Interface Unit (Fiu) - Rockwell Automation ICSTT-RM280N-EN-P Manual

1. Description Trusted TMR 24Vdc Digital Output Module – 40 Channel
Figure 2 shows a simplified block diagram of the Trusted 24 Vdc Digital Output Module.
Figure 2 Functional Block Diagram

1.1. Field Termination Unit (FTU)

The Field Termination Unit (FTU) is the section of the I/O Module that connects all three
FIUs to a single field interface. The FTU provides the Group Fail Safe Switches and passive
components necessary for signal conditioning, over-voltage protection, and EMI/RFI
filtering. When installed in a Trusted Controller or Expander Chassis, the FTU field connector
interconnects to the Field I/O Cable Assembly attached at the rear of the Chassis.
The SmartSlot link is passed from the HIU to the field connections via the FTU. These signals
go directly to the field connector and maintain isolation from the I/O signals on the FTU. The
SmartSlot link is the intelligent connection between Active and Standby Modules for co-
ordination during Module replacement.

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 24 Vdc Digital Output Module, the FIU contains one stage of
the output switch structure, and sigma-delta (ΣΔ) output circuit for each of the 40 field
outputs. Two additional ΣΔ circuits provide optional monitoring of the external field I/O
supply voltage.
4 Issue 14 Rockwell Automation Publication ICSTT-RM280N-EN-P