Overview
The Allen-Bradley 1771-ASB Series B remote I/O adapter module connects PLC-5 controllers to distributed I/O systems across extended distances. The 1771-ASB bridges the controller’s backplane to remote I/O devices through serial communication, eliminating the need for long parallel wiring runs and reducing system complexity. This module is essential for large-scale automation installations where I/O devices must be physically separated from the central processor.
Key Features
- Transmits data up to 10,000 cable-feet at 57.6K baud for long-distance connectivity
- Supports three I/O addressing methods: 2-slot, 1-slot, and 1/2-slot configurations
- Handles mixed I/O modules (4, 6, 8, 16, or 32-point combinations) without restrictions
- Automatic I/O configuration verification on power-up for system integrity
- Flexible DIP switch configuration for multiple scanning modes and addressing schemes
- Compatible with all Allen-Bradley Remote I/O (RIO) scanners and I/O chassis
Technical Specifications
- Remote I/O Serial Communication: 57.6 kbps, 115.2 kbps, 230.4 kbps
- Maximum Cable Distance: 10,000 feet (57.6K baud); 2,500 feet (230.4K baud)
- I/O Addressing Modes: 2-slot, 1-slot, 1/2-slot
- Supported I/O Modules: 4, 6, 8, 16, 32-point (any mix)
- I/O Groups per Rack: Up to 8 groups
- I/O Terminals per Group: 16 input, 16 output
- Configuration: DIP switches and module configuration plugs
- Connectors: Remote I/O serial link and backplane interface
- Dimensions: 3.5 × 6.5 × 2.0 inches (89 × 165 × 51 mm)
- Certifications: UL Listed, CSA Certified, Class I Division 2 Groups A-D, CE Compliant
Typical Applications
The 1771-ASB is widely deployed in:
- Factory Automation: Extended I/O control for assembly lines, conveyor systems, and material handling
- Distributed Control Systems (DCS): Remote monitoring and actuation across large facilities, oil refineries, and water treatment plants
- Process Control: Remote sensor inputs and valve/motor outputs in manufacturing and chemical processing
- Remote Sensing & Actuation: Systems with distributed temperature sensors, pressure switches, and motor controllers across multiple locations
Compatibility & Replacements
Compatible With
- Allen-Bradley PLC-5 series controllers
- Allen-Bradley Remote I/O (RIO) scanners and networks
- Universal I/O chassis (Series A and B)
- 1771 series I/O modules (all addressing modes)
- 1771-S4A and 1771-S4B RIO scanners
Replaces / Drop-In Replacement For
The 1771-ASB Series B directly replaces earlier Series A adapters in systems requiring Series B response characteristics. The 1771-ASB/E (extended mode) is a later evolution supporting additional features but uses identical mounting and backplane interfaces. Verify your system’s scanner compatibility before substitution.
Works With
- Allen-Bradley Remote I/O (RIO) protocol
- PLC-5 ladder logic programming via RSLogix 5
- 1771 I/O chassis backplane communication
- Serial communication links up to 10,000 feet
- Multi-adapter network configurations for redundancy and scalability
