Allen-Bradley 1771-IR RTD Input Module

Allen-Bradley 1771-IR RTD Input Module (Series D) is a six-channel RTD input module for PLC-5 I/O racks that reads resistance-temperature detectors (RTDs) and feeds temperature data to the controller via the 1771 I/O bus. Each channel accepts RTD sensors (commonly Pt100) configured as 2-wire or 3-wire connections, enabling lead-resistance compensation per channel. As part of the 1771 I/O family, the 1771-IR is designed to interface with Allen-Bradley controllers that support block transfer, functioning as an analog input module for RTD measurements. The terminal layout supports three conductors per RTD channel (A, B, C) with a dedicated functional ground, and the documentation notes 2-wire and 3-wire RTD connections for channels 2–5. Typical applications include industrial temperature monitoring and process control in PLC-5-based automation environments.