Overview
The Allen-Bradley 1746-NI4 /A is a high-resolution 4-channel analog input module designed for the SLC 500 programmable logic controller family. Each channel is independently configurable for voltage or current measurement, delivering flexible signal conditioning in a single-slot form factor. This module supports both legacy system maintenance and modern industrial automation integration, capturing analog process signals with 16-bit resolution and minimal electrical noise.
Key Features
- Four independent analog input channels — each selectable per channel for ±10V DC or ±20 mA current inputs
- 16-bit resolution — delivers 305.176 µV per LSB (voltage) and 1.22 µA per LSB (current) for precise signal capture
- Non-isolated differential inputs — reduces common-mode noise and improves measurement accuracy in noisy industrial environments
- DIP switch configuration — on-board switches simplify per-channel input type selection without firmware recompilation
- Single-slot mounting — compatible with both fixed and modular SLC 500 hardware
- Removable terminal block — expedites wiring and field replacement
Technical Specifications
- Voltage Input Range: ±10 V DC (–1 LSB)
- Voltage Input Impedance: 1 MΩ
- Current Input Range: ±20 mA (nominal), ±30 mA (maximum)
- Current Input Impedance: 250 Ω
- Resolution: 16-bit (14-bit effective)
- Accuracy (Voltage) at 25°C: ±0.284% of full scale
- Accuracy (Voltage) at 60°C: ±0.504% of full scale
- Accuracy (Current) at 25°C: ±0.365% of full scale
- Accuracy (Current) at 60°C: ±0.642% of full scale
- Update Time: 512 microseconds
- Bandwidth: 10 Hz
- Operating Temperature Range: 0°C to 60°C (32°F to 140°F)
- Backplane Current (5V): 25 mA
- Backplane Current (24V): 85 mA
- Connector: 15-pin D-shell (AIFM)
Typical Applications
- Process control systems — temperature, pressure, flow, and level monitoring in chemical, pharmaceutical, and food processing
- Instrumentation and data acquisition — multi-channel sensor signal conditioning with high resolution
- Legacy system maintenance — replacement module for discontinued SLC 500 installations
- Industrial equipment retrofits — integrating modern analog sensors into mature automation platforms
Compatibility & Replacements
Compatible With
- SLC 500 fixed-I/O controllers
- SLC 500 modular systems with 1746-A2, 1746-A4 chassis
- RSLogix 500 programming software
- Rockwell Automation CompactLogix and MicroLogix (with gateway interface)
Replaces / Drop-In Replacement For
- 1746-NI4 (original revision)
- Equivalent legacy 4-channel analog input modules from competing vendors (verify with integrator)
Works With
- RSLogix 500 — native tag-based analog input configuration and scaling
- PLC-5 and SLC 500 networks — direct backplane communication, no external interface required
- Industrial protocols: DH+, EtherNet/IP (via gateway module)
- Sensor standards: 4–20 mA transmitters, ±10V analog sensors, potentiometers
