Product Overview

The Allen-Bradley 1746-NO4I is a high-precision analog output module designed for the SLC 500 PLC platform. This module provides four independent current-sourcing channels, enabling the controller to interface with various field devices that require analog command signals. It converts digital data from the SLC processor into proportional 0 to 20 mA or 4 to 20 mA signals.

This module is essential for applications requiring smooth, continuous control rather than simple binary switching. It is a single-slot solution that fits into any available slot in an SLC 500 chassis, communicating directly with the CPU over the backplane. The 1746-NO4I is widely utilized for regulating proportional valves, controlling the frequency of variable speed drives (VFDs), and providing setpoints to specialized industrial instruments.

Technical Characteristics

• Output Channels: 4 Current-Sourcing Analog Outputs

• Signal Range: 0 to 20 mA or 4 to 20 mA (User-selectable)

• Resolution: 16-bit binary (Full scale)

• Backplane Current Draw: 55 mA at 5V DC and 195 mA at 24V DC

• Digital-to-Analog Conversion: Successive approximation for high accuracy

• Isolation: Backplane-to-output isolation tested at 500V DC; no channel-to-channel isolation

• Step Response: 2.5 ms (typical) at 95% of full scale

• Load Impedance Range: 0 to 500 Ohms

• Connector Type: Removable terminal block for easier maintenance and wiring

• Operating Temperature: 0°C to 60°C (32°F to 140°F)

• Dimensions: 3.5 x 13 x 14.5 cm

• Weight: 0.2 kg

Industrial Integration and Reliability

The 1746-NO4I is optimized for deterministic process control where signal integrity is paramount. By utilizing 16-bit resolution, the module provides exceptionally fine granularity, allowing for precise increments in valve positioning or motor speed. This level of detail is critical in chemical dosing, thermal regulation, and high-accuracy material handling.

Configuration is handled seamlessly through RSLogix 500 software, where the user can define the scaling of the output data to match the engineering units of the physical application. The module features robust diagnostic capabilities, including detection of open-circuit conditions in the current loop. Designed to withstand the rigorous electromagnetic interference (EMI) typical of factory floors, the 1746-NO4I ensures that your process variables remain stable and responsive. Although the SLC 500 line has moved toward legacy status, this module remains a vital component for maintaining and expanding existing automation infrastructures.