Overview
The Allen-Bradley 1746-NR4 is a dedicated RTD/Resistance analog input module engineered for the SLC 500 family of programmable controllers. The 1746-NR4 is a RTD/Resistance analog input module that contains 4 inputs. This module converts analog data from RTD units or other resistance inputs into digital form for processing by the controller. Series B design ensures compatibility with both fixed and modular SLC 500 architectures, making it an ideal solution for temperature monitoring and resistance-based process control.
Key Features
- Four isolated input channels supporting 2-, 3-, or 4-wire RTD sensor connections
- Multiple RTD types: Supports platinum, copper, nickel, and nickel-iron sensors.
- Flexible resistance ranges: Accepts 0–150 Ω, 0–300 Ω, 0–500 Ω, and 0–1000 Ω signals.
- Sigma-delta A/D conversion for stable, noise-immune measurements
- Automatic self-calibration when configuration parameters change
- Configurable output: Temperature (°C, °F) or direct resistance (ohms) values
- Channel status LEDs for quick diagnostics and fault identification
- Backplane-powered—no external power supply required
Technical Specifications
- Input Channels: 4 RTD/resistance inputs
- Resolution: 16 bits with a step response at 95% of 12–300 ms
- Backplane Current: 50 mA at 5V DC or 50 mA at 24V DC
- Operating Temperature Range: 0°C to 55°C (32°F to 131°F) in most slots; 0°C to 60°C (32°F to 140°F) in the rightmost slot
- Update Time: 17 ms to 1.2 seconds (configurable bandwidth)
- Communication: Backplane communication with SLC processor using an image table of 8 input and 8 output words
- Module Status: One module status LED plus four channel indicators
- Weight: 250 grams
- Certifications: UL, CSA, CE (where applicable)
- Software Compatibility: RSLogix 500 programming environment
Typical Applications
Typical applications include temperature monitoring, displacement measurement, process feedback, and equipment position sensing where high-accuracy RTD inputs are required. The 1746-NR4 is widely used in:
- Industrial ovens, furnaces, and thermal process control
- Pharmaceutical and food processing with temperature validation
- HVAC and environmental monitoring systems
- Oil/gas pipeline and storage tank temperature logging
- Water treatment and cooling tower management
- Material handling and machinery thermal protection
Compatibility & Replacements
The 1746-NR4 (Series B) is a direct plug-in module for SLC 500 controllers and integrates seamlessly into existing automation systems. It is programmed and configured using Rockwell Automation’s RSLogix 500 software environment. When replacing legacy analog input modules, verify your controller’s I/O configuration and available backplane slots. For systems requiring similar RTD/resistance measurement capability in CompactLogix or ControlLogix architectures, consult Rockwell Automation product selection guides. The module’s four isolated channels and automatic self-calibration provide reliable long-term operation with minimal maintenance intervention.
