Allen-Bradley 1746-NR8 SLC 500 RTD Input Module | 8-Channel

Allen-Bradley 1746-NR8 RTD/Resistance Input Module

• Brand: Allen-Bradley
• Series: SLC 500 programmable controller family
• Model Number: 1746-NR8
• Module Type: 8-channel RTD/Resistance analog input
• Input Channels: Eight isolated RTD/resistance inputs
• Temperature Resolution: 0.01° Celsius precision
• A/D Conversion: Sigma-delta modulation technology

Technical Performance Specifications

• The 1746-NR8 provides eight independent measurement channels in one module
• Update time is configurable from 6 milliseconds to 2 seconds per channel
• It supports multiple RTD types including Platinum, Copper, Nickel, and Nickel Iron
• Built-in programmable low-pass digital filtering reduces signal noise
• Auto-calibration occurs at power-up and can cycle every 5 minutes
• Step response time is 60 milliseconds in, 2.5 milliseconds out
• Nine status LEDs indicate module operation and individual channel status
• Broken sensor detection identifies open or short circuit conditions automatically

Sensor Compatibility and Wiring Options

• Supported RTD Types: Platinum (385/3916), Copper (426), Nickel (618/672), Nickel Iron (518)
• Wiring Configurations: Supports 2-wire, 3-wire, and 4-wire RTD connections
• Direct Resistance Inputs: 0-150Ω, 0-300Ω, 0-500Ω, 0-1000Ω ranges available
• Recommended cable: Belden 9501 for 2-wire, Belden 9533/83503 for 3/4-wire RTDs
• Use lower gauge cables (like AWG #16) for long wire runs to maintain accuracy
• Each Removable Terminal Block (RTB) terminal accepts single wire connections only
• Compatible with Allen-Bradley 1746-RT-35 terminal block for field wiring

Electrical and Isolation Specifications

• Backplane current: 100 mA at 5V DC and 55 mA at 24V DC
• Maximum power consumption: 1.82 watts total (0.5W at 5V DC, 1.32W at 24V DC)
• Isolation: 500V AC for 1 minute between inputs and backplane/chassis ground
• Continuous isolation: 5V DC between individual measurement channels
• Maximum common-mode voltage tolerance: ±1 volt
• Maximum permanent overload protection: ±5V DC or ±5 mA
• No external power supply required - powered entirely from backplane

Environmental and Installation Details

• Operating temperature: 0°C to 60°C (32°F to 140°F)
• Storage temperature: -40°C to 85°C (-40°F to 185°F)
• Relative humidity: 5% to 95% non-condensing
• Install in any 1746 chassis slot except slot 0 (reserved for processor)
• Compatible with both fixed style and modular style SLC 500 hardware
• Single-slot design maximizes channel density in control panels
• Ideal for temperature monitoring and mechanical position sensing applications

Frequently Asked Questions

• What is the measurement resolution for temperature readings?
  This module provides high precision with 0.01° Celsius resolution for accurate temperature monitoring.
• Can I measure resistance values directly?
  Yes, the module accepts direct resistance inputs from 0-150Ω to 0-1000Ω for various applications.
• Where should I install this module in the chassis?
  Install the 1746-NR8 in any slot of a 1746 chassis except slot 0, which is processor-only.
• Does the module require separate power wiring?
  No external power is needed - the module receives power directly from the SLC 500 backplane.