Overview
The Allen-Bradley 1746-NO4I is a 4-channel analog current output module for the SLC 500 platform. The module contains 4 outputs (0…20mA) and has a backplane current of 55 milliamps at 5 Volts DC and 195 milliamps at 24 Volts DC, with 14-bits resolution. This module is installed directly into a standard SLC 500 chassis in a single slot and is commonly used in legacy industrial automation systems requiring analog current loop control.
Key Features
- Four-channel analog output module using 16-bit 2’s complementary binary format with output range of 0 to +20 mA with full-scale current output of 21 mA
- Incorporates optical isolation and advanced filtering circuitry to reduce electrical noise and ensure stable signal integrity
- Fast response of 512 microseconds update time
- Supports user-supplied 24V dc power supplies; when external 24V dc power is used, the module only draws 5V dc current from the SLC backplane
- Uses screw-terminal connections and integrates with SLC processors across multi-chassis systems
- Supports standard SLC 500 environmental ratings, including 0–60 °C operation, industrial vibration tolerance, and high dielectric withstand levels
Technical Specifications
- Number of Output Channels: 4
- Output Signal Type: Current loop
- Output Range: 0 to +20 mA
- Full-Scale Output: 21 mA (5% overrange)
- Resolution: 14 bits
- Data Format: 16-bit 2’s complement binary
- Update Time: 512 microseconds
- Backplane Current @ 5V DC: 55 mA
- Backplane Current @ 24V DC: 195 mA
- Operating Temperature: 0 to 60 °C
- Mounting: Single slot in SLC 500 chassis
- Terminal Type: Screw terminals
- Isolation: Optical isolation per channel
Typical Applications
Provides current-loop output signals for controlling industrial devices such as valves, drives, actuators, and instrumentation requiring 0–20 mA signals. If used with a Proportional-Integral-Derivative controller, the analog output is assigned to represent the Control Output (CO) of the PID controller. Common applications include process control loops, variable frequency drive (VFD) command signals, and analog signal retransmission for data logging and monitoring.
Compatibility & Replacements
Compatible With
- SLC 500 fixed hardware style (compact/single-chassis systems)
- SLC 500 modular hardware style (multi-chassis configurations)
- SLC 5/01, SLC 5/02, SLC 5/03, SLC 5/04, and SLC 5/05 processors
- SLC 500 communication adapters for multi-chassis communication
- Standard SLC 500 backplane configurations
Replaces / Drop-In Replacement For
The 1746-NO4I is the current-output-only variant of the SLC 500 analog output family. Verify compatibility with your system integrator before ordering, as this module is not interchangeable with the 1746-NO4V (voltage output) or 1746-NIO4I (combination input/output) modules without reconfiguration.
Works With
- RSLogix 500 / Studio 5000 (legacy SLC project import and compatibility)
- SLC 500 standard I/O configuration tools
- 4-20 mA process instrumentation and control devices
- PLC ladder logic control programs targeting analog output data
- Multi-chassis SLC systems via communication modules
