1756-EN2T ControlLogix EtherNet/IP Communication Module Guide

The Allen-Bradley 1756-EN2T module is a high-performance ControlLogix communication interface engineered by Rockwell Automation to provide high-capacity connectivity across plant-wide EtherNet/IP networks. Serving as the primary active replacement for the legacy 1756-ENBT, the 1756-EN2T doubles TCP/IP and CIP connection capacity to meet modern automation requirements.

Specifically, the module supports distributed I/O control, peer-to-peer messaging, and enterprise SCADA data collection. While ControlLogix processors utilize the 1756-EN2T for high-speed Ethernet communication, manufacturing plants frequently require this modern layer to exchange operational data with legacy PLC-5 and SLC 5/04 systems on Data Highway Plus (DH+).

Key Architecture & Technical Specifications of the 1756-EN2T

Engineered for high-density discrete manufacturing and continuous process control, the 1756-EN2T introduces significant performance enhancements over predecessor cards:

• Expanded Connection Capacity: Supports up to 128 TCP/IP connections and a maximum of 256 CIP (Common Industrial Protocol) connections (128 exclusive-owner and 128 listen-only/input-only).
• Enhanced Packet Handling: Capable of handling up to 10,000 I/O packets per second (pps) and 3,200 messaging packets per second—more than double the throughput of the 1756-ENBT.
• Physical Network Ports: Features one 10/100 Mbps copper RJ45 Ethernet port alongside a convenient front USB 2.0 Type-B port for local configuration and firmware flashing without needing network pre-configuration.
• Backplane Throughput: High-speed ControlLogix backplane communication delivering seamless bridging across standard 1756 chassis (1756-A4, A7, A10, A13, A17).

Integrating ControlLogix EtherNet/IP Networks with Legacy DH+

In facilities running modern ControlLogix controllers equipped with 1756-EN2T modules, engineers often encounter the challenge of collecting data from existing PLC-5 and SLC 5/04 lines:

• The Obsolete Rack Solution: Historically required maintaining a dedicated 1756 chassis housing an extra 1756-EN2T/ENBT and a discontinued 1756-DHRIO module solely to route packets across backplanes.
• The Modern Gateway Solution: Deploying an external ANC-100e DH+ Gateway eliminates the need for any secondary 1756 rack. The ANC-100e sits directly on the plant Ethernet network, accepting MSG instructions from the 1756-EN2T and bridging them natively to DH+ nodes.

Technical Comparison: 1756-ENBT vs. 1756-EN2T vs. ANC-100e

Compare communication specifications and deployment requirements across modular rack hardware and standalone gateways:

Modern Migration & Plant Network Optimization Strategies

Depending on your industrial facility’s current hardware infrastructure:

• Standardizing ControlLogix Chassis on 1756-EN2T: Upgrading older 1756-ENBT modules to 1756-EN2T cards prevents network saturation and resolves CIP connection exhaust in large distributed I/O racks.
• Direct DH+ Bridging via ANC-100e: When interfacing the modern 1756-EN2T network to legacy PLC-5 or SLC 5/04 racks, deploy the ANC-100e Gateway to avoid sourcing obsolete ControlLogix 1756-DHRIO bridge hardware.
• Field Service & Programming: For mobile technicians programming legacy DH+ machinery from 64-bit Windows 10 and 11 laptops, use the ANC-120e USB to DH+ Cable.

For further details on ControlLogix network migration, explore our 1756-DHRIO Module Guide or our comprehensive 1756-DHRIO & ProSoft Alternative Guide.