Product Overview

The Allen-Bradley 1756-RIO is a specialized communication interface designed to bridge modern ControlLogix™ systems with legacy Universal Remote I/O (RIO) networks. This module allows a ControlLogix processor to either act as a Scanner, controlling up to 32 remote adapters (such as 1771 PLC-5 I/O or 1794 FLEX I/O), or as an Adapter, allowing a secondary controller to see the ControlLogix chassis as a remote rack.

By utilizing the 1756-RIO, industrial facilities can perform phased migrations from older PLC-5 or SLC 500 platforms to ControlLogix without the immediate expense of replacing all field wiring and I/O racks. The module natively handles discrete, analog, and complex block transfer (BT) data, providing a high-speed link that maintains the deterministic performance required for critical machinery and process control.

Technical Characteristics

• Dual-Mode Functionality: Configurable as a Scanner (to control remote racks) or an Adapter (to be controlled by a master).

• Network Capacity: Supports up to 32 physical adapter locations in Scanner mode.

• Data Handling: Manages Block Transfers (BT) and scheduled I/O connections automatically without complex messaging logic.

• Connection Limit: Handles up to 10 scheduled I/O connections simultaneously.

• Wiring Compatibility: Uses standard 1771-CD or Belden 9463 "Blue Hose" twinaxial cable.

• Baud Rate Support: Compatible with all standard RIO speeds (57.6k, 115.2k, and 230.4k baud).

• Power Consumption: Draws 450 mA at 5.1V DC and 5 mA at 24V DC.

• Isolation: Continuous 50V isolation between the RIO network and the backplane for signal protection.

• Chassis Integration: Occupies a single slot in any 1756 ControlLogix chassis (e.g., 1756-A7, 1756-A13).

• Heat Dissipation: 2.5 Watts power dissipation with 8.5 BTU/hr thermal output.

• Dimensions: 3.6 x 14 x 14.6 cm; Weight: 0.26 kg.

Industrial Applications and Integration

The 1756-RIO is an essential tool for facility upgrades where downtime must be minimized. It allows for the integration of existing 1771 I/O racks into a new ControlLogix architecture, enabling the use of modern Studio 5000™ programming while retaining proven field devices.

The module supports both simplex and redundant controller topologies, ensuring that mission-critical data remains available even in high-availability systems. In addition to I/O control, it can interface with legacy HMI systems and SCADA networks that communicate via RIO protocols. Built to survive harsh industrial environments, the module operates efficiently in temperatures up to 60°C. While this product was officially discontinued by the manufacturer in 2012, it remains a critical spare part for maintaining the reliability and connectivity of aging industrial infrastructure across the globe.