Overview
The Allen-Bradley 1746-NI4 is a high-resolution analog input module designed for the SLC 500 control platform. Known for its flexibility in accepting both current and voltage inputs, this module has been a vital component in industrial automation systems for decades. Although it has been discontinued, the 1746-NI4 remains widely used in legacy systems that depend on reliable analog input capabilities. This module is ideal for maintenance technicians and control engineers maintaining existing SLC 500 installations.
Key Features
- Four (4) non-isolated differential, voltage or current selectable input channels
- 16-bit resolution for precise signal measurement and high accuracy
- Input signals ranging from -10 to 10 volts DC as well as current inputs between -20 to 20 milliamps
- Compatible with fixed or modular style SLC 500 hardware for flexible system integration
- Shielded twisted-pair cable support and single-point grounding design to minimize electrical noise
- Removable terminal block for simplified wiring and field replacement
Technical Specifications
The NI4 Analog Input module contains 4 analog input channels that are user selectable per channel for voltage or current to support a variety of monitoring and controlling applications.
- Voltage Input Range: ±10 Volts DC -1 LSB with impedance of 1 mega Ohms
- Current Input Range: +/-20 mA (nominal) and +/-30 mA (maximum) with 250 Ohms input impedance
- Resolution: 16-bit resolution with 305.176 µV per LSB for voltage mode
- Conversion Method: Sigma-Delta technology for accurate signal conversion
- Update Time: 512 microseconds for all channels operating in parallel
- Backplane Current: 25 milliamps at 5 volts and 85 milliamps at 24 volts
- Operating Temperature: 0°C to 60°C (32°F to 140°F)
- Bandwidth: 10 Hertz
- Mounting: Single slot SLC 500 I/O chassis mount
- Overall Accuracy: +/-0.284% of full scale at 25°C, +/-0.504% at 60°C (voltage mode)
Typical Applications
The Allen-Bradley 1746-NI4 provides four analog input channels, each configurable for either voltage or current signals, and its design ensures high performance and adaptability in process control applications. Common uses include:
- Process monitoring and control in chemical, pharmaceutical, and food processing industries
- Temperature, pressure, and flow rate measurement
- Legacy system maintenance and module replacement
- Data acquisition from 4–20 mA transmitters and ±10 V sensors
Compatibility & Replacements
Compatible With
- SLC 500 fixed architecture controllers
- SLC 500 modular chassis (I/O slot positions only, not processor slot)
- Allen-Bradley programming software (RSLogix 500)
- Industrial process control systems requiring analog input capabilities
Replaces / Drop-In Replacement For
The 1746-NI4 is the standard 4-channel analog input module for SLC 500 systems. Modern replacements include CompactLogix or ControlLogix analog input modules for new designs, but for legacy SLC 500 systems, this module remains the direct replacement. Verify compatibility with your system integrator before ordering.
Works With
- RSLogix 500 (SLC 500 development software)
- Allen-Bradley SLC 500 communication networks
- ControlNet and Ethernet/IP gateways (via suitable interface modules)
- DIP switch configuration for per-channel voltage/current mode selection
- Removable terminal block accessories for field maintenance
