Allen-Bradley 1771-IR RTD Input Module

The Allen-Bradley 1771-IR RTD Input Module is a six-channel analog input card for PLC-5 systems that directly measures resistance-temperature detectors (RTDs) through 3-wire connection schemes. Designed to plug into a 1771 I/O backplane, it provides six independent RTD input channels that feed temperature data into the controller for precise process monitoring. Each channel supports 3-wire RTD configurations to compensate lead resistance and deliver consistent readings across the module. The 1771-IR is used in legacy PLC-5 installations to monitor temperature in applications such as chemical processing, metalworking, food and beverage, HVAC, and other temperature-critical processes where multiple RTD probes must be read simultaneously. Field wiring connections are made to the module’s RTD terminals, and the module communicates with the PLC-5 processor as part of the analog I/O path, enabling deterministic scan data and straightforward integration into existing control schemes. As part of the 1771 I/O family, the IR module shares common mounting, power, and backplane interfaces with other RTD and analog modules, simplifying rack layout and maintenance in facilities with older Rockwell Automation equipment.