The Allen-Bradley 1756-IRT8I is a high-precision analog input module designed for the ControlLogix platform. It provides eight isolated channels capable of interfacing with various temperature sensors, including multiple thermocouple types and resistance temperature detectors (RTDs), as well as millivolt signals. This module is engineered for industrial environments requiring reliable, high-resolution data acquisition and channel-to-channel isolation.

Features

• Eight isolated input channels for enhanced noise immunity and signal integrity.
• Supports a wide range of thermocouple types including B, C, D, E, J, K, N, R, S, T, and TXK/XK (L).
• Configurable for RTD and millivolt input signals.
• IEEE 32-bit floating point data format for high-precision processing.
• Fast module scan time of 1 ms to support dynamic process control.
• Integrated diagnostic features to monitor for open circuits and out-of-range inputs.

Technical Specifications

Installation Guidelines

• Ensure the ControlLogix chassis is powered down before inserting or removing the 1756-IRT8I module to prevent electrical damage.
• Use appropriate shielded cabling for all thermocouple and RTD inputs to minimize electromagnetic interference (EMI).
• Maintain proper grounding practices for the chassis and field wiring to ensure signal accuracy and safety.
• Verify that the module is fully seated in the chassis slot and that the locking tab is engaged before securing the wiring arm.
• Avoid routing signal cables in close proximity to high-voltage power lines or high-frequency switching equipment.

Applications

This module is frequently utilized in process control applications such as temperature monitoring in furnaces, chemical reactors, and boiler systems, as well as general-purpose industrial instrumentation where channel isolation is required to prevent ground loops.

FAQ

Is the 1756-IRT8I compatible with all ControlLogix chassis?
Yes, this module is designed to fit into any standard ControlLogix I/O chassis.

Does this module require external power for the sensors?
The module draws power from the backplane; however, field-side wiring must be correctly terminated according to the specific sensor type (RTD or Thermocouple) being used.

What is the primary benefit of the isolated channels?
The 250V isolation between channels protects the module and the controller from potential differences between sensors, significantly reducing the risk of common-mode noise and measurement errors.