Allen-Bradley 1771-ASB/E/A Remote I/O Adapter Module – High-Speed PLC-5 to Remote I/O Communication

Product Overview

The Allen-Bradley 1771-ASB/E/A Remote I/O Adapter Module​ is a critical communication interface manufactured by Rockwell Automation under the Allen-Bradley brand, designed to bridge the gap between a PLC-5 processor and remote I/O racks in distributed control system architectures. As an essential component of the legacy 1771 I/O product family, the Allen-Bradley 1771-ASB/E/A Remote I/O Adapter Module​ enables a PLC-5 controller to communicate with I/O modules located up to 10,000 feet (3,048 meters) away from the processor, using a high-speed Remote I/O (RIO) network operating at 57.6 kbps. This capability allows engineers to distribute I/O points across large industrial facilities—such as chemical plants, steel mills, and power generation stations—without the need for expensive, long-distance point-to-point wiring runs between the controller and each field device.

The Allen-Bradley 1771-ASB/E/A Remote I/O Adapter Module​ installs directly into a 1771 I/O chassis (such as the 1771-A1B, 1771-A2B, or 1771-A3B) and communicates with the chassis backplane to scan all installed I/O modules. It then transmits the collected I/O data back to the PLC-5 processor over a single twisted-pair cable using the proprietary Remote I/O protocol. The module supports configurable addressing through a set of rotary switches, allowing the user to define the starting group address (0–7) for the rack. With support for up to 8 I/O groups (each group representing 16 I/O points), the Allen-Bradley 1771-ASB/E/A Remote I/O Adapter Module​ can handle a substantial amount of distributed I/O, making it an efficient solution for large-scale automation systems where centralized control with remote field I/O is required.

Designed for the demanding conditions of industrial environments, the Allen-Bradley 1771-ASB/E/A Remote I/O Adapter Module​ features a rugged construction with an open-style IP20 enclosure, suitable for installation in standard control cabinets. It operates reliably across a temperature range of 0°C to 60°C with 5% to 95% non-condensing humidity tolerance, and carries UL, cUL, and CE certifications. The module draws its power directly from the 1771 chassis backplane (5V DC at approximately 1.5A), eliminating the need for a separate external power supply. Its DIN rail or panel mounting options, combined with the removable terminal block for the RIO network connection, make installation and maintenance straightforward. For facilities still operating PLC-5 and PLC-3 systems—or those in the process of migrating to newer platforms—the Allen-Bradley 1771-ASB/E/A Remote I/O Adapter Module​ represents a vital link in maintaining and extending the life of proven, mission-critical automation infrastructure.

Technical Specifications