1756-EN3TR | Allen-Bradley ControlLogix Dual-Port 10/100 Mbps Ethernet/IP Interface Module

Module Overview

The 1756-EN3TR is a high-performance Ethernet/IP communication interface specifically engineered for the Allen-Bradley ControlLogix platform. Featuring a built-in two-port switch, this module facilitates high-speed data exchange, distributed I/O control, and seamless integration with industrial networks. It is a cornerstone for modern automation architectures, supporting advanced networking features such as Device Level Ring (DLR) for enhanced system resiliency and Integrated Motion on EtherNet/IP for precise synchronized axis control.

Detailed Engineering Specifications

The 1756-EN3TR is designed to occupy a single slot in any standard 1756 chassis, drawing power directly from the backplane to manage complex network traffic and motion synchronization.

• Module Type: EtherNet/IP Communication Interface

• Physical Ports: Two (2) Ethernet (RJ-45) and One (1) USB 1.1 (Type B)

• Ethernet Transfer Speed: 10/100 Mbps (Full/Half Duplex)

• USB Transfer Rate: 12 Mbps (Local configuration/Programming)

• Network Topologies: Linear, Star, and Device Level Ring (DLR)

• Backplane Current (5.1V DC): 1.0 Ampere

• Backplane Current (24V DC): 3 Milliamps

• Total Power Dissipation: 5.1 Watts

• Thermal Dissipation: 17.4 BTU/hr

• Integrated Motion Support: Up to 128 Axes of motion

• Isolation Voltage: 30V Continuous (Basic Insulation Type)

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

• Chassis Compatibility: 1756-A4, -A7, -A10, -A13, -A17 (Series B and C)

• Slot Width: Single-slot occupancy

Networking Capabilities and Topology Support

A primary advantage of the 1756-EN3TR is its native support for Device Level Ring (DLR) technology. In a DLR configuration, the module's dual ports allow the network to be wired in a physical ring. If a single cable failure occurs, the module automatically reroutes traffic, ensuring the PLC system remains operational without a loss of I/O control. This high-availability feature is critical for large-scale manufacturing lines and process plants where downtime is costly.

Integrated Motion on EtherNet/IP

The 1756-EN3TR is optimized for high-performance motion control. It is capable of managing up to 128 axes of Integrated Motion on EtherNet/IP, allowing the ControlLogix processor to synchronize servo drives (such as Kinetix series) directly over the standard Ethernet network. This eliminates the need for specialized SERCOS hardware and simplifies the wiring of multi-axis machines.

Technical FAQ

Can the two Ethernet ports be assigned different IP addresses?

No. The two RJ-45 ports on the 1756-EN3TR act as an internal unmanaged switch. They share a single MAC address and a single IP address. They are intended for daisy-chaining or creating a DLR ring, not for bridging two separate subnets.

What is the function of the USB port on the front faceplate?

The USB port is intended for local configuration and temporary programming access. It allows a technician to connect a laptop directly to the module to configure the IP address or perform firmware updates via RSLinx without needing to be on the primary network.

Is this module compatible with standard 1756 power supplies?

Yes. The 1756-EN3TR is fully compatible with all standard ControlLogix power supplies (e.g., 1756-PA72, 1756-PB75) and redundant power supply configurations (e.g., 1756-PA75R).