1771-IXHR Allen-Bradley PLC-5 Thermocouple Input Module

Allen-Bradley 1771-IXHR Thermocouple / mV Input Module

The Allen-Bradley 1771-IXHR, also cataloged as the High-Resolution Thermocouple Input Module, operates as a dedicated hardware component for precise thermal signal acquisition within PLC-5 industrial control platforms.

Hardware Specifications

Allen-Bradley Industrial Control Characteristics

The 1771-IXHR module utilizes 16-bit A/D conversion to ensure high-resolution acquisition of low-level millivolt signals. The hardware architecture manages I/O density scaling by supporting eight differential channels within a single chassis slot, enabling efficient integration into dense PLC-5 control cabinets. Cold junction compensation (CJC) is integrated directly into the module circuitry, minimizing thermal drift and maintaining measurement accuracy across diverse ambient conditions. Furthermore, the module provides channel-to-system isolation, which prevents ground loops and electrical transients from propagating into the backplane bus. Proactive firmware flash compatibility—where applicable—and built-in open-circuit diagnostics ensure that thermal data remains reliable for time-critical process control loops.

Frequently Asked Questions

Q: Does the 1771-IXHR support all common thermocouple types?

A: Yes, the module is configurable for J, K, T, E, R, S, B, and N thermocouple types, allowing for flexible application across various process monitoring requirements.

Q: How are open-circuit conditions identified by the module?

A: The module performs continuous diagnostic monitoring; if the resistance between differential inputs exceeds the threshold of a closed thermocouple loop, the module flags an open-circuit bit in the PLC image table.

Field Installation Guidelines

1. Safety Precautions: Verify that the PLC-5 chassis power supply is disconnected before installation to prevent electrical damage to the backplane.
2. Mounting: Slide the 1771-IXHR module into the designated slot of the 1771-I/O chassis. Ensure the connector is fully seated into the backplane, then lock the module using the top and bottom latches.
3. Wiring: Use thermocouple-grade extension wire to connect field sensors to the module terminals. Ensure that shielding is terminated to the chassis ground rail to suppress electromagnetic interference.
4. Validation: After applying power, observe the module status LEDs. A successful self-diagnostic boot indicates the module is calibrated and ready to process incoming millivolt signals from the field devices.