<h2>Overview</h2>
<p>The <strong>Allen-Bradley 1756-CN2R</strong> is a ControlLogix communications module engineered to provide reliable, high-speed ControlNet connectivity within distributed PLC systems. As part of the ControlLogix platform, this redundant communications module supports dual-channel ControlNet architecture, enabling fault-tolerant network topologies ideal for mission-critical industrial automation applications. The module installs into a single slot of any compatible 1756 ControlLogix chassis and interfaces directly with the system backplane for deterministic data transfer.</p>
<h2>Key Features</h2>
<ul>
<li><strong>Redundant ControlNet Connectivity:</strong> Dual BNC ControlNet ports support linear and redundant network topologies, maintaining uptime in critical applications.</li>
<li><strong>High-Speed Transmission:</strong> Each port operates at 5 Mbps, enabling real-time deterministic control across distributed devices.</li>
<li><strong>Extensive Connection Capacity:</strong> Supports up to 128 Logix connections and 99 network nodes over Common Industrial Protocol (CIP).</li>
<li><strong>USB Configuration Port:</strong> Integrated USB interface enables local module configuration and maintenance without requiring network access.</li>
<li><strong>Hot-Swappable Design:</strong> Module can be inserted or removed during controller operation, minimizing downtime for maintenance and upgrades.</li>
<li><strong>Isolation and Safety:</strong> 30 VDC isolation between ControlNet and system backplane with 500V basic insulation testing.</li>
</ul>
<h2>Technical Specifications</h2>
<p>The 1756-CN2R delivers robust performance in demanding control environments:</p>
<ul>
<li><strong>Communication Protocol:</strong> ControlNet via Common Industrial Protocol (CIP)</li>
<li><strong>Data Rate:</strong> 5 Mbps per ControlNet port</li>
<li><strong>Logix Connections:</strong> Maximum 128</li>
<li><strong>Network Nodes:</strong> Up to 99</li>
<li><strong>Ports:</strong> 2 × BNC ControlNet + 1 × USB</li>
<li><strong>Backplane Current Draw:</strong> 1300 mA @ 5.1 VDC; 3 mA @ 24 VDC</li>
<li><strong>Power Dissipation:</strong> 6.6 W (22.5 BTU/hr)</li>
<li><strong>Operating Temperature:</strong> 0–60 °C (32–140 °F)</li>
<li><strong>Dimensions:</strong> 7.87 in × 3.15 in × 1.65 in (200 mm × 80 mm × 42 mm)</li>
<li><strong>Isolation Voltage:</strong> 30 VDC</li>
<li><strong>Insulation Testing:</strong> 500 V for 1 minute (basic insulation)</li>
<li><strong>Certifications:</strong> UL, CE, CUL, KC, CCC, NRTL, RCM</li>
</ul>
<h2>Typical Applications</h2>
<p>The 1756-CN2R is deployed in diverse industrial environments where network reliability and redundancy are essential:</p>
<ul>
<li>Food & beverage packaging and processing automation with distributed I/O networks</li>
<li>Automotive assembly systems requiring synchronized multi-controller communication</li>
<li>Pharmaceutical manufacturing with strict uptime and traceability requirements</li>
<li>Material handling and logistics automation with redundant network topologies</li>
<li>Oil & gas production systems with geographically distributed control nodes</li>
<li>Water/wastewater treatment plants requiring fail-safe networked instrumentation</li>
</ul>
<h2>Compatibility & Replacements</h2>
<h3>Compatible With</h3>
<ul>
<li>All ControlLogix controllers and processor modules</li>
<li>1756 ControlLogix chassis (1756-A4, 1756-A7, 1756-A10, 1756-A13, 1756-A17)</li>
<li>Standard ControlLogix power supplies (1756-PA72/C, 1756-PA75/B, and equivalents)</li>
<li>Common Industrial Protocol (CIP) networks and EtherNet/IP gateways</li>
<li>RSLogix 5000 and Studio 5000 engineering environments</li>
</ul>
<h3>Replaces / Drop-In Replacement For</h3>
<p>The 1756-CN2R is a Series C revision that supersedes Series A and B variants of the 1756-CN2R. Verify compatibility with your system integrator before ordering.</p>
<h3>Works With</h3>
<ul>
<li><strong>Software Platforms:</strong> RSLogix 5000, Studio 5000, FactoryTalk View</li>
<li><strong>Communication Protocols:</strong> ControlNet, EtherNet/IP (via gateway), CIP Messaging</li>
<li><strong>Redundancy Standards:</strong> Linear and ring topologies, peer-to-peer communication</li>
</ul>
