Overview
The Allen-Bradley 1746-NO4I is a 4-channel analog output module designed for the SLC 500 control platform. It is an SLC 500 four-channel analog output module using 16-bit 2’s complementary binary format. The module installs directly into any standard SLC chassis, providing four isolated current outputs. This discontinued module remains widely used in legacy process control and machine automation applications where precise analog output signals are essential.
Key Features
- Four current outputs with output range 0 to +20 mA with full-scale current output of 21 mA
- Optical isolation and advanced filtering circuitry to reduce electrical noise and ensure stable signal integrity
- Embedded selector switch to allow selection of power supply source; internal power from backplane or external source at 24 ±10% DC at 195 mA max
- Screw-terminal connections with removable terminal strip for simplified wiring and ease when replacing the module
- Standard SLC 500 environmental ratings including 0–60 °C operation, industrial vibration tolerance, and high dielectric withstand levels
Technical Specifications
- Output Type: Current signals from 0 to 20 mA
- Number of Channels: 4
- Data Format: 14-bit resolution
- Full-Scale Output: 21 mA with 5% overrange capability
- Response Time: 512 microseconds update time
- Backplane Current Draw: 55 mA at 5V DC or 195 mA at 24V DC
- Power Supply: 24 Volts DC
- Backplane Isolation: 500 Volts DC
- Load Range: 0 to 500 ohms
- Operating Temperature: 0 to 60 degrees Celsius
- Humidity: 5 to 95% relative humidity range
- Series: SLC 500
- Mounting: DIN rail / SLC chassis slot
Typical Applications
The module provides current-loop output signals for controlling industrial devices such as valves, drives, actuators, and instrumentation requiring 0–20 mA signals. This module is widely used in process control, machine automation, and applications requiring precise analog output regulation. When used with a Proportional-Integral-Derivative controller, the analog output is assigned to represent the Control Output (CO) of the PID controller. When wiring this module, shielded communication cable such as Belden 8761 or equivalent should be used with lengths kept as short as possible.
Compatibility & Replacements
Compatible With
- SLC 500 fixed and modular chassis systems
- Allen-Bradley SLC 5/01, 5/02, 5/03, 5/04, 5/05 controllers
- Studio 5000 Logix Designer (for legacy system integration and migration planning)
- Analog control loops using PID output
- EtherNet/IP networks via communication adapters
Replaces / Drop-In Replacement For
- Direct replacement for earlier 1746-NO4I Series A modules
- Functionally equivalent to 1746-NO4V (voltage output variant)
Works With
- RSLogix 500 (legacy programming environment)
- SLC 500 Modular Hardware Style User Manual (publication 1747-UM011)
- Multi-chassis systems with SLC communication adapters
- Process control applications using loop power from external sources
