Allen-Bradley 1746-NR4 SLC 500 RTD/Resistance Analog Input Module

Product Overview

The Allen-Bradley 1746-NR4 is a dedicated SLC 500 RTD/Resistance Analog Input Module engineered for precise temperature and resistance measurement in industrial control systems. With four (4) backplane-isolated channels, this module interfaces seamlessly with a wide range of RTD sensors—including Platinum (385), Platinum (3816), Copper (426), Nickel (618), Nickel (672), and Nickel Iron (518)—as well as direct resistance devices. Its sigma-delta A/D conversion method ensures stable, high-resolution readings, making it a trusted choice for demanding automation environments.

As part of the SLC 500 family, the 1746-NR4 integrates easily into both fixed and modular chassis configurations (excluding Slot 0, which is reserved for the controller or adapter). The module performs automatic self-calibration whenever filter frequency, input type, excitation current, or channel enablement changes, reducing manual setup time and enhancing long-term accuracy.

Technical Specifications

Compatible RTD Sensors and Resistance Ranges

The 1746-NR4 supports a diverse set of RTD types, enabling flexible deployment across various temperature sensing applications. Compatible RTD sensors include:

• Platinum (385): 100, 200, 500, and 1000 ohms
• Platinum (3816): 100, 200, 500, and 1000 ohms
• Copper (426): 10 ohms
• Nickel (618): 120 ohms
• Nickel (672): 120 ohms
• Nickel Iron (518): 604 ohms

In addition to RTD sensing, the module accepts direct resistance inputs across four ranges: 0–150 ohms, 0–300 ohms, 0–500 ohms, and 0–1000 ohms. This versatility allows the 1746-NR4 to measure not only temperature but also displacement or movement in devices such as pick-and-place mechanisms and clamping equipment.

Industry Applications

The Allen-Bradley 1746-NR4 excels in applications requiring reliable temperature monitoring and resistance measurement. Its four-channel design makes it ideal for:

• Industrial ovens and furnaces where precise RTD-based temperature control is critical.
• Packaging machinery that uses resistance-based position sensors to verify clamp or actuator positions.
• Process lines needing multi-point temperature sensing with fast update times (17 ms minimum).

With a resolution of 0.01 °C and a bandwidth up to 65.5 Hz, the module captures fine temperature variations, enabling tighter process control and reduced waste.

Installation & Setup Guidance

Install the 1746-NR4 in any I/O slot of a fixed or modular SLC 500 chassis, except Slot 0. For fixed-style hardware, use a 1746-A2 expansion chassis if additional slots are required. The module does not require an external power supply; it draws 50 mA from the backplane at both 5 V DC and 24 V DC. After mounting, configure the input types and filter frequencies via the SLC 500 programming software. The module automatically recalibrates when you change filter frequency, input type, excitation current, or enable a channel—no manual calibration is needed.

Maintenance & Reliability

The 1746-NR4 features built-in broken sensor detection that flags open or shorted RTD circuits, simplifying diagnostics and reducing downtime. Its optical isolation of 500 V DC (1 minute) protects the backplane and other modules from ground potential differences. With an operating temperature range of 0 to 60 °C and storage capability from -40 to 85 °C, the module suits typical industrial enclosures. Periodic inspection of wiring connections and sensor integrity helps maintain measurement accuracy.

Selection Guide & Purchasing Advice

Before purchasing the 1746-NR4, verify that your SLC 500 system has an available I/O slot (not Slot 0) and that your RTD sensors match the supported types listed above. Confirm the required resistance range (0–150, 0–300, 0–500, or 0–1000 ohms) aligns with your application. For genuine Allen-Bradley 1746-NR4 modules with reliable availability, PLC Source PRO offers a dependable sourcing solution for industrial automation spares.