Purchase now: Allen-Bradley 1756-EN3TR EtherNet/IP Bridge
Purchase now: Atlantechdrives provides you the 1756-EN3TR, an elite, high-performance EtherNet/IP communication bridge module engineered by Rockwell Automation for the ControlLogix 1756 programmable automation controller (PAC) platform. In modern industrial automation, network resilience is just as critical as processor speed. The 1756-EN3TR is specifically designed to provide ultra-reliable, high-capacity network routing with built-in fault tolerance. Unlike standard single-port modules, the «TR» designation stands for «Twisted-Pair Ring,» meaning this module features dual embedded RJ45 copper ports operating at 10/100 Mbps. These dual ports allow the module to natively support Device Level Ring (DLR) topologies without requiring an external managed switch. This ensures that if a single Ethernet cable is severed on the factory floor, the network instantly routes traffic the other way around the ring, guaranteeing zero downtime and seamless continuous production. Capable of supporting up to 128 TCP/IP connections and 256 CIP connections, it is the premier networking bridge for highly demanding applications such as massive CIP Motion architectures, sprawling automotive assembly lines, and critical food and beverage packaging machinery.
Technical Specifications of the 1756-EN3TR
The 1756-EN3TR is a powerhouse of data routing, capable of processing up to 10,000 I/O packets per second, ensuring that your central L7 or L8 processor never starves for field data.
- Part Number: 1756-EN3TR
- Platform: ControlLogix 1756 System
- Network Protocol: EtherNet/IP
- Embedded Ports: 2 x RJ45 (10/100 Mbps, Auto-Negotiation)
- Supported Topologies: Device Level Ring (DLR), Linear, Star
- Connection Capacity: 128 TCP/IP connections, 256 CIP connections
- Configuration Port: USB 2.0 (Front panel)
- Backplane Current Draw: 1.0 A at 5.1V DC; 3.0 mA at 24V DC
Expert Tips: The Power of Device Level Ring (DLR)
Network architecture dictates plant reliability. Expert Tip: When setting up a DLR network using the 1756-EN3TR, you must designate one node on the ring as the «Active Ring Supervisor.» This specific module actively sends out beacon frames (typically every 400 microseconds) around both ring ports to verify network integrity. If a cable break occurs, the supervisor detects the lost beacon and instantly unblocks its secondary port, allowing data to flow in both directions and healing the network in less than 3 milliseconds. Never assign more than one Active Ring Supervisor on a single physical DLR network, or severe packet storms and network collisions will occur. You can, however, assign backup supervisors that will automatically take over if the primary supervisor module fails.
Installation Advice: USB Configuration and BOOTP
Unlike legacy Ethernet modules that required complex serial cables or MAC address hunting to assign the initial IP address, the 1756-EN3TR features a highly convenient front-facing USB 2.0 port. During initial cabinet commissioning, automation engineers can simply plug a standard USB cable from their laptop to the module, instantly open RSLinx Classic, and assign the static IP address, subnet mask, and gateway without ever needing to use the sometimes-finicky BOOTP/DHCP Server utility over the network. Once configured, ensure the rotary switches on the module faceplate are correctly set (usually to ‘999’ to use the software-configured IP) and lock the cabinet.
Frequently Asked Questions (FAQs)
Q: Can the 1756-EN3TR be used in a standard Star topology instead of a Ring?
A: Yes, absolutely. You can simply plug one of the RJ45 ports into a standard industrial Ethernet switch (like a Stratix 5700) and leave the second port empty, functioning perfectly in a traditional Star architecture.
Q: Does the 1756-EN3TR support ControlLogix Redundancy?
A: Yes. The 1756-EN3TR is fully certified for use in high-availability ControlLogix Redundancy architectures, ensuring seamless I/O control transfer between primary and secondary chassis during a hardware failure.
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This high-capacity Ethernet bridge supports Device Level Ring (DLR) and pairs perfectly with modern ControlLogix 5580 controllers.
