Rockwell Automation T8843 Trusted 40 Channel Digital Input Versatile FTA - Manual (Page 7)

Trusted
TM
Digital Input Versatile FTA T8843
Issue 4 Sep 05 PD-T8843 7
1. Description
The Trusted TM 40 Channel Digital Input Versatile FTA T8843 provides termination for a maximum of 40
input channels from various types of field devices which generate a digital input. The 40 channels are
arranged in five power groups each comprising eight identical channels. Figure 2 below shows the
configuration of a single channel within a group.
Figure 2 Single Channel Schematic
Each power group is supplied from dual 24V dc (or 120V dc dependent upon input module type) feeds
which are ‘commoned’ via diodes on the VFTA. The supply is then fed to each channel within the
group.
The supply voltage to the field is fed via the 315mA fuse. The incoming signal (digital) from the field
device is fed through the 50mA fuse which effectively limits the input signal. Line monitoring
components (if required) provide the necessary thresholds used by the input module to detect the field
loop/device status, i.e. open/short circuit, alarm etc.
The cable linking the 40 channels on the input module to the VFTA is terminated at five 10-way
connectors (TBG1 to TBG5). SmartSlot (Version 1) signals from the module are connected to a single
7-way connector (TBGSS). The dual dc field power supplies are connected to the VFTA via five 4-way
connectors (TBFP1 to TBFP5). Forty 3-way connectors are used for the field loops (TB1 to TB40).