Overview
The Allen-Bradley 1771-ASB is a Remote I/O Adapter Module designed for PLC-5 and 1771 Series I/O systems. This module acts as a communication interface that allows controllers to manage remote I/O racks at distances up to 10,000 cable-feet, enabling distributed control architectures without requiring dedicated panel space at the main PLC location.
Key Features
- Extended Range Communication: Transmits data up to 10,000 cable-feet at 57.6K baud, with faster backplane scanning and data transmission up to 2,500 cable-feet at 230.4K baud
- Flexible I/O Addressing: Supports any mix of I/O (4, 6, 8, 16 or 32 points) and supports three methods of I/O addressing: 1/2-slot, 1-slot and 2-slot
- Configurable Transmission Speed: Data transmission speeds of 57.6 kbps, 115 kbps, and 230 kbps
- Automatic Configuration Verification: Checks I/O configuration on power-up to verify I/O module placement
- Low Current Consumption: Requires only 1.2A @ 5V DC
- Status Indicators: Front panel contains green ACTIVE, red ADAPTER FAULT, and red I/O RACK FAULT indicators
Technical Specifications
- Communication Protocol: Remote I/O (RIO)
- Maximum Remote Racks: Up to 32 remote racks per module
- Slot Compatibility: Installs in Allen-Bradley Universal I/O Chassis models 1771-A1B, 1771-A2B, 1771-A3B, or 1771-A4B
- Module Position: Must be placed in the extreme left slot of the Universal I/O Chassis
- Supported Subnets: An Allen-Bradley/EPICS subnet allows for up to 8 adapters on one Allen-Bradley subnet link
Typical Applications
The 1771-ASB is commonly used in distributed manufacturing environments, remote packaging lines, and multi-location facilities where I/O modules cannot be co-located with the main processor. It enables cost-effective wiring solutions by supporting high-density I/O packs at distances up to 10,000 feet, reducing material costs and installation complexity.
Compatibility & Replacements
Compatible with Allen-Bradley PLC-5 and 1771 Series I/O systems. The 1771-ASB is available in multiple revisions (Series B, C, D, E) with progressive enhancements. Newer revisions can emulate Series B adapters, allowing use of 1771-S4A and -S4B scanners which require slower response for proper operation. For integration with EPICS control systems and VMEbus architectures, the 1771-ASB functions as a subnet adapter connecting remote 1771 I/O Chassis and RediPANEL devices.
