Configured for resistance temperature detector measurement in Allen-Bradley PLC platforms, the Allen-Bradley 1771-IR (1771-IR RTD Input Module) provides direct physical/electrical execution.
Suffix Breakdown & Model Matrix
1771: Universal I/O chassis-based hardware architecture for Allen-Bradley control systems.
I: Input module function designation.
R: Resistance Temperature Detector (RTD) channel sensor interface configuration.
16 bits + sign (0.1 deg C / 0.1 deg F or 0.01 Ohm)
Wiring Arm
1771-WF (or 1771-WH)
High-Density Analog Processing and Backplane Determinism
The 1771-IR digitizes resistance values from three-wire RTD sensors, converting temperature metrics directly into Natural Binary, BCD, or direct Ohm data formats. Integrated into ControlNet or EtherNet/IP deterministic remote I/O link architectures, the internal analog front-end incorporates open-wire lead detection while isolating field sensor noise to preserve backplane bus communication velocity across adjacent PLC-5 chassis submodules.
Frequently Asked Questions
Q: Does the 1771-IR RTD input module require an external power supply?
A: No external power supply is needed; the 1771-IR derives all logic and signal excitation power directly from the 1771 chassis 5 VDC backplane bus.
Q: What keying position is required on the 1771 chassis slot backplane for the 1771-IR module?
A: Keying bands must be installed on the chassis backplane connector between pins 10 and 12, or between pins 28 and 30.
Field Installation Guidelines
Turn off 1771 chassis backplane supply power prior to inserting or removing the 1771-IR module from the rack slot.
Connect 3-wire RTD sensor conductors to the 1771-WF swing arm, ensuring matching lead lengths to maintain lead-wire resistance compensation balance.
Route RTD field signal cables in dedicated shielded twisted-pair conduits away from high-voltage AC motor drives and switching power sources.
Earth ground cable shields at a single ground point at the panel side to eliminate ground loop noise coupling across low-resistance sensor channels.
