Product Overview

The 1756-EN2T is an Allen-Bradley ControlLogix EtherNet/IP communication module from Rockwell Automation. It provides a copper Ethernet interface between the ControlLogix backplane and EtherNet/IP networks, supporting controller access, remote I/O, drives, HMIs, and other EtherNet/IP devices. The module uses a single RJ45 port with 10/100 Mbps communication and supports up to 128 TCP connections and 256 CIP connections. It can also route messages between EtherNet/IP networks and other communication paths within a ControlLogix architecture. The chassis-based design allows installation in any compatible ControlLogix chassis slot. Rockwell Automation currently lists this catalog number as an active product.

Technical Specifications — 1756-EN2T

Rockwell specifies a single Category 5 RJ45 Ethernet interface, 10/100 Mbps operation, 128 TCP connections, and 256 CIP connections for this module.

A-B 1756-EN2T

Key Features and Benefits — 1756-EN2T

• EtherNet/IP bridge for ControlLogix systems.
• Single copper RJ45 Ethernet connection.
• Supports real-time I/O messaging and explicit messaging.
• 128 TCP and 256 CIP connection capacity.
• Supports remote I/O and EtherNet/IP device communication.
• Can bridge messages between networks.
• Supports integrated motion applications with up to 8 axes.
• One-slot chassis installation.
• Suitable for PLC, HMI, drive, and distributed I/O architectures.

Compared with the older 1756-ENBT, this module provides substantially greater connection capacity and is identified by Rockwell as its functional replacement.

Related Models

1756-ENBT: Earlier ControlLogix EtherNet/IP bridge with 64 TCP and 128 CIP connections. It was discontinued in 2021, with the 1756-EN2T listed as the functional replacement.

1756-EN2F: Fiber-optic EtherNet/IP bridge supporting 100 Mbps communication and 128 TCP connections.

1756-EN2TR: Dual-port EtherNet/IP bridge with an embedded switch for network topologies requiring two copper Ethernet ports.

1756-EN3TR: Higher-capacity dual-port EtherNet/IP bridge intended for larger ControlLogix networking applications.

Installation and Maintenance — 1756-EN2T

Before replacement, record the IP address, network configuration, firmware revision, chassis position, and connected EtherNet/IP devices. Confirm the existing Ethernet topology and connection requirements before commissioning the replacement.

During maintenance, inspect the RJ45 connector, Ethernet cable, chassis backplane connector, and module status indicators. Verify network communication and I/O connections after installation. If communication is intermittent, check cable quality, switch configuration, IP addressing, and network loading before replacing the module.

Personally, I would back up the existing network configuration first. On an established ControlLogix system, restoring the correct IP and communication parameters is often more important than simply installing the replacement hardware.

Product Warranty — 1756-EN2T

Warranty coverage should be confirmed according to the supplied condition, such as new surplus, refurbished, or tested-used. For critical automation spares, procurement records should include the complete catalog number, series/revision, firmware information, inspection status, serial number where available, and warranty period.

When sourcing the A-B 1756-EN2T, verify the ControlLogix chassis, firmware compatibility, IP configuration, Ethernet topology, and required connection capacity before purchase. Rockwell Automation currently lists the product as active.