Product Overview

The Allen-Bradley 1756-IR6I is a 6-channel isolated RTD (Resistance Temperature Detector) input module designed for the Rockwell Automation ControlLogix platform. It converts minute resistance changes from various RTD sensors into high-resolution digital temperature values or resistance readings, providing precise process monitoring for demanding industrial environments. The module occupies a single slot in any standard 1756 chassis and interfaces seamlessly with ControlLogix processors via the backplane.

Technical Specifications

• Input Channels: 6 independently isolated channels (channel-to-channel and channel-to-backplane)
• Sensor Compatibility: Supports 2/3/4-wire RTDs (Pt100, Pt200, Pt500, Pt1000, Ni120, Cu10, etc.) and direct resistance inputs
• Measurement Range: 1–487 Ω, 2–1000 Ω, 4–2000 Ω, and 8–4000 Ω
• Resolution & Accuracy: 16-bit resolution; ±0.05% full scale accuracy at 25°C
• Data Format: Integer mode or IEEE 32-bit floating-point mode with temperature linearization
• Update Rate: Minimum 25 ms per channel (varies with filter settings)
• Backplane Current: 250 mA @ 5V DC, 125 mA @ 24V DC
• Terminal Block: Requires 20-pin removable terminal block (1756-TBNH or 1756-TBSH)

Main Features and Advantages

• Superior Isolation: Each of the six channels is electrically isolated from the others and the backplane (250V AC continuous), effectively eliminating ground loops and protecting against voltage spikes in harsh plant environments.
• Flexible Data Processing: Offers two data formats. Floating-point mode provides direct engineering units (°C or °F) with built-in temperature linearization, process alarms, and rate-of-change alarms. Integer mode provides raw resistance data with real-time sampling.
• Advanced Noise Rejection: Includes configurable 50/60 Hz notch filters to suppress line noise and digital filtering to smooth transient spikes, ensuring stable and accurate measurements even near heavy electrical equipment.
• Comprehensive Diagnostics: Continuously monitors each channel for open-circuit (sensor break), short-circuit, and over/under-range conditions, reporting detailed fault information directly to the controller for rapid troubleshooting.