1. Description
Trusted 40 Channel 120 Vac Digital Input FTA
4
Issue 7
Rockwell Automation Publication ICSTT-RM290F-EN-P
The supply voltage to the field is fed via the 50 mA fuse. This effectively limits the current in
the field loop. The incoming signal (digital) from the field device is fed to the digital input
module via a resistive divider. This divides the voltage down to levels suitable for an
analogue measurement.
Revision E T8824 FTAs use two power resistors in series, as shown in the circuit diagram in
Figure 2. Earlier revisions used 4x4 resistor arrays. The resistor arrays on the top half are 68
K and the bottom resistor arrays are 1 K.
Line monitoring is limited to voltage detection on the module. Refer to Trusted TMR 120 Vac
Digital Input Module 40 Channel, publication
The cable linking the 40 channels on the input module to the FTA is terminated at five 10-
way connectors (SK1 to SK5). The input signals from the field (40-off) are connected by 2-
wire arrangements terminated on 5-off 16-way terminal blocks.
