1771-ASB | Allen-Bradley Remote I/O (RIO) Adapter Module | PLC-5 Series

Overview

The 1771-ASB (Part Number: 1771-ASB) serves as the primary communication link between a remote 1771 I/O chassis and a Master controller, such as a PLC-5 or a ControlLogix system equipped with a RIO scanner. By converting the backplane signals of the 1771 rack into the Universal Remote I/O protocol, this module allows for distributed control architectures over long distances. It facilitates high-speed data transfer of discrete and block transfer data, ensuring synchronized performance between the central processor and remote field devices.

Detailed Technical Specifications

The 1771-ASB is designed for high-reliability data acquisition within the 1771 Universal I/O chassis framework.

• Communication Protocol: Universal Remote I/O (RIO)

• Baud Rate Support: 57.6 kbit/s, 115.2 kbit/s, and 230.4 kbit/s (Distance dependent)

• Backplane Current Draw: 1.0 Amp @ 5V DC

• Addressing Capabilities: Supports 1/2-slot, 1-slot, and 2-slot addressing modes

• Input/Output Capacity: Up to 32 connections for I/O rack image mapping

• Physical Connections: Requires 1771-WG or 1771-WB wiring arm for interface stability

• Recommended Cable: Belden 9463 (Twinaxial)

• Status Diagnostics: Integrated LED indicators for Active, Adapter Fault, and I/O Rack Status

• Noise Immunity: Compliant with NEMA Standard ICS 2-230

Environmental and Physical Parameters

Built to withstand rigorous plant-floor conditions, the module maintains strict operational tolerances.

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

• Storage Temperature: -40°C to 85°C (-40°F to 185°F)

• Relative Humidity: 5% to 95% (Non-condensing)

• Mounting: Internal Chassis Slot (requires the leftmost slot of the 1771 rack)

• Unit Weight: 0.91 kg (2.00 lbs)

• Keying: Plastic edge-connector tabs for error-free installation (Positions 16 to 18)

Integration FAQ

Where should the 1771-ASB be installed in the rack?The module must always occupy the leftmost slot (the "adapter slot") of a 1771 Universal I/O chassis. It cannot be placed in standard I/O slots.

How is the communication speed determined?The baud rate is configured via internal DIP switches on the module. It must match the scanner’s rate and is limited by the total cable length of the RIO link (e.g., 230.4 kbit/s up to 2,500 feet).

Can this module work with ControlLogix?Yes, if the ControlLogix system utilizes a 1756-DHRIO module or a similar gateway, the 1771-ASB can remain as the remote rack interface, allowing for phased system migrations.