A-B 1771-ASB Remote I O Adapter

Allen-Bradley 1771-ASB Remote I/O Adapter Module

 

 

The Allen-Bradley 1771-ASB is a Remote I/O (RIO) Adapter Module used in the PLC-5 / 1771 I/O system. It is installed in a remote I/O chassis and acts as a communication interface between the I/O rack and the PLC processor.

In simple terms, it is not the brain of the system, but the “translator + communication bridge” between remote field I/O racks and the main PLC CPU over the RIO network.

Key Specifications

• Model: 1771-ASB
• Brand: Allen-Bradley (Rockwell Automation)
• Series: PLC-5 / 1771 Remote I/O System
• Type: Remote I/O Adapter Module
• Function: RIO communication interface for 1771 I/O chassis
• Communication Protocol: Remote I/O (Blue Hose / Twinax cable)
• Data Rates:
  • 57.6 kbps
  • 115.2 kbps
  • 230.4 kbps
• Max Distance:
  • up to ~10,000 ft (low baud rate)
• Backplane Current: ~1.0 A @ 5V
• Wiring: 1771-WG / 1771-WB wiring arm
• Mounting: Left-most slot in 1771 chassis (adapter slot)

What it does (simple explanation)

PLC CPU (1785-L40B / L80B)
↓ (RIO “Blue Hose” network)
1771-ASB Adapter Module
↓
1771 I/O Rack (inputs / outputs / analog modules)
↓
Field devices (sensors, valves, motors)

It allows one PLC to control remote I/O racks over long distances.

Main Functions

• Acts as remote I/O rack communication interface
• Transfers I/O data between PLC and remote chassis
• Supports input/output image mapping
• Handles rack addressing via DIP switch configuration
• Enables long-distance distributed control systems
• Supports multiple I/O modules per rack

Key Features

• High-speed industrial Remote I/O communication
• Supports long cable distances (plant-wide networks)
• Flexible rack addressing (1/2-slot, 1-slot, 2-slot modes)
• Built-in diagnostics (LED status indicators)
• Compatible with full 1771 I/O module range
• Very robust for harsh industrial environments

Applications

• Oil & gas distributed control systems
• Power plants
• Steel mills
• Water treatment systems
• Large manufacturing plants
• Conveyor systems with remote cabinets