The Allen-Bradley 1771-IG TTL Input Module is a digital input module that accepts TTL-level signals, converting external logic states into PLC-friendly inputs within the 1771 I/O architecture. It is used to monitor discrete devices such as sensors and switches, feeding their binary conditions into the controller for sequencing, interlocks, and safety logic. This TTL input option in the 1771 family provides a dedicated interface for TTL-compatible digital circuits in industrial automation applications.
