The Allen-Bradley 1756-CN2R/B is a Series B ControlNet communication bridge module engineered for the ControlLogix platform. This module facilitates deterministic, high-speed data exchange between controllers, remote I/O, and field devices. By utilizing a dual-channel coaxial architecture, the 1756-CN2R/B provides critical redundancy, ensuring continuous network operation even in the event of a single-cable failure or signal degradation.

Features

• Redundant Media Support: Dual BNC connectors allow for redundant ControlNet cabling, enabling automatic failover if a primary link is compromised.
• Deterministic Throughput: Maintains a constant 5 Mbps data rate, essential for time-critical control applications.
• High Capacity: Supports up to 99 nodes on a single network and manages up to 131 total connections (128 of which are dedicated to Logix controllers).
• Integrated USB Port: Includes a dedicated USB port for local configuration and diagnostic access.
• Series B Reliability: Optimized hardware design for improved stability and performance in demanding industrial environments.

Installation Guidelines

• ESD Protection: Always utilize an ESD wrist strap or similar grounding device when handling the module to prevent damage to sensitive internal components.
• Backplane Insertion: Ensure the ControlLogix chassis is powered down before inserting or removing the module. Align the module with the chassis guides and seat firmly to ensure proper backplane connection.
• Cabling: Use only 1786-RG6 quad-shield coaxial cables for network connections to maintain signal integrity and meet specification requirements.
• Environmental: Mount the module in an environment that maintains an ambient temperature between 0 and 60 degC. Ensure adequate airflow around the chassis to prevent heat buildup.
• Grounding: Ensure the ControlLogix chassis is properly grounded according to local electrical codes to minimize EMI impacts.

Technical Specifications

FAQ

Q: Does this module support non-redundant configurations?
A: Yes, the 1756-CN2R/B can operate in a single-cable configuration, though it is specifically designed to provide redundant media capability for high-availability systems.

Q: What is the primary difference between Series A and Series B?
A: The Series B hardware revision features updated internal processing components for improved reliability and firmware compatibility within the ControlLogix ecosystem.