Product Overview

The Allen-Bradley 1756-CN2R is a high-capacity ControlNet communication interface designed for the ControlLogix platform. This module serves as a critical link for high-speed deterministic networking, allowing for the seamless transfer of time-critical I/O data and messaging between nodes. Engineered for mission-critical applications, the 1756-CN2R features dual-channel media redundancy, which protects against network downtime by providing an automatic failover mechanism should a primary cable fault occur.

This module acts as a bridge, routing data between the ControlNet network and the ControlLogix backplane, making it an essential component for distributed I/O, inter-controller communication, and remote configuration in complex industrial architectures.

Technical Capabilities and Network Performance

The 1756-CN2R is optimized for large-scale deployments requiring high connection density and deterministic throughput.

• Communication Rate: Supports a fixed ControlNet data rate of 5 Mbps.

• Connection Capacity: Supports up to 128 Logix connections and 131 total USB/CIP connections.

• Network Nodes: Capable of addressing up to 99 nodes per segment.

• Redundancy: Dual BNC ports for redundant media attachment to ensure system availability.

• Backplane Compatibility: Compatible with all 1756 ControlLogix chassis and supports removal and insertion under power (RIUP).

• Packet Performance: Features enhanced processing power compared to standard 1756-CNB modules, allowing for higher packets-per-second throughput.

Hardware Specifications

• Module Type: Communication Bridge / Redundant Media Interface

• Current Draw: 1100 mA at 5.1V DC; 3 mA at 24V DC.

• Power Dissipation: 5.6 Watts.

• Isolation Voltage: 50V (continuous), Basic Insulation Type; tested at 707V DC for 60 seconds.

• Physical Interface: 2 ControlNet BNC ports and 1 USB 1.1 port for local configuration.

• Module Width: Single-slot.

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

• Weight: 0.25 kg.

• Dimensions: 14 x 13.2 x 3.5 cm.

Application and Installation

The 1756-CN2R is frequently utilized in process control, oil and gas, and automotive manufacturing where network failure is not an option. It allows the ControlLogix controller to interface with remote I/O racks, variable frequency drives (VFDs), and other ControlNet-compliant devices. The module's integrated display provides immediate status on network health and node addressing, simplifying troubleshooting for site engineers.