The FTA (Field Termination Assembly) provides a centralized termination point for 40 digital input channels. The field power is supplied from dual 24 Vdc feeds, which are connected via diodes on the FTA. A green LED indicates the presence of power. The supply voltage to the field is fed through a 50mA fuse, which limits the current in the field loop. The incoming digital signal from the field device is directly connected to the digital input module. Line monitoring components (if required) provide the necessary thresholds for the input module to detect the field loop/device status, such as open/short circuit, alarm, etc. The 40 channels on the input module are terminated at the 96-way socket SK1.
