Allen-Bradley 1756-EN2T EtherNet/IP Replacement for ControlLogix

Product Overview

Allen-Bradley 1756-EN2T EtherNet/IP Replacement for ControlLogix: Seamless Migration & Smooth Transition

The Allen-Bradley 1756-EN2T is a high-performance EtherNet/IP Bridge Communication Module designed for the ControlLogix 1756 platform. As legacy ControlLogix systems age and original 1756-EN2T units reach end-of-life or become increasingly difficult to source, plant engineers and system integrators face mounting pressure to maintain network uptime without triggering a full control system overhaul. TOPNLMS supplies verified 1756-EN2T modules that serve as direct drop-in replacements, enabling a smooth, low-risk migration path that preserves your existing wiring infrastructure, Logix 5000 programming environment, and EtherNet/IP network topology.

Whether you are replacing a failed unit in a running production line, building a spare-parts inventory for a multi-site ControlLogix deployment, or executing a planned upgrade from an older 1756-ENET or 1756-ENBT bridge module, the 1756-EN2T delivers the dual-port EtherNet/IP connectivity and Device Level Ring (DLR) media redundancy that modern industrial networks demand. Its compatibility with the standard 1756 chassis backplane means no mechanical modifications are required — the module slots directly into any 1756-A4, 1756-A7, 1756-A10, 1756-A13, or 1756-A17 chassis without adapter plates or bracket changes.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful 1756-EN2T migration rarely involves a single module swap. In practice, field engineers coordinate the replacement alongside several interconnected components to ensure the entire ControlLogix node returns to full operation without extended downtime.

On the controller side, the 1756-L71 or 1756-L73 ControlLogix CPU typically resides in the same chassis and continues to run the existing Logix 5000 project without reprogramming — the 1756-EN2T uses the same CIP routing table structure as its predecessors. If the chassis power supply is aging, this is an ideal time to inspect or replace the 1756-PA75 or 1756-PB75 power supply module, since the 1756-EN2T draws slightly more backplane current than the older 1756-ENBT.

For I/O integration, digital and analog I/O modules such as the 1756-IB16 (16-point 24VDC digital input) and 1756-OB16E (16-point 24VDC digital output with diagnostics) remain fully compatible and continue to communicate over the backplane without any wiring changes. Analog modules like the 1756-IF8 (8-channel analog input) maintain their existing channel scaling and tag mappings in the Logix project.

Where the legacy system used a 1756-DNB DeviceNet Bridge to connect field devices, the 1756-EN2T upgrade often coincides with a broader network modernization — migrating DeviceNet nodes to EtherNet/IP-capable drives and sensors, reducing the need for separate bridge modules. Similarly, if the installation includes a 1756-DHRIO Data Highway Plus / Remote I/O bridge for legacy PLC-5 or SLC 500 communication, that module can coexist in the same chassis alongside the new 1756-EN2T without conflict.

On the HMI side, PanelView Plus terminals communicating via EtherNet/IP require no application changes after the 1756-EN2T swap — simply update the target IP address in FactoryTalk View if it has changed. Programming connectivity is maintained through the existing 1756-EN2T path in RSLinx Classic or the Logix Designer communication path, eliminating the need for a separate 1784-U2DHP USB-to-DH+ programming cable in most modern installations.

For installations where signal isolation is required between the ControlLogix backplane and field wiring, 1492-AIFM analog interface modules and 1492-IFM digital interface modules continue to terminate field wiring without modification, since the 1756-EN2T replacement does not alter the I/O module slot assignments or terminal block wiring.

Retrofit Guidance FAQ

Q: Do I need to modify my existing Logix 5000 program after replacing 1756-ENBT with 1756-EN2T?
A: In most cases, no. The 1756-EN2T uses the same CIP communication path and tag structure. You may need to update the module definition in Studio 5000 to reflect the new catalog number and verify the firmware revision, but existing ladder logic, function block diagrams, and produced/consumed tag configurations remain intact.

Q: Is the wiring compatible — can I reuse existing Ethernet cables?
A: Yes. The 1756-EN2T uses standard RJ-45 connectors. Existing Cat5e or Cat6 patch cables connect directly. The second port enables DLR ring topology if desired, but can be left unused for a standard linear or star network configuration identical to the legacy setup.

Q: How do I handle IP address migration?
A: The 1756-EN2T supports BOOTP, DHCP, and static IP assignment. If the legacy module used a static IP, configure the same address on the replacement unit using the Rockwell BOOTP/DHCP Server utility or RSLinx before installing it in the chassis. This ensures zero disruption to SCADA, HMI, and remote I/O communication paths.

Q: Will the 1756-EN2T fit in my existing chassis without mechanical changes?
A: Yes. The 1756-EN2T occupies a single standard 1756 backplane slot. It is physically identical in form factor to the 1756-ENBT and 1756-ENET, requiring no bracket modifications, adapter plates, or chassis changes.

Q: What firmware version is required on the ControlLogix CPU?
A: The 1756-EN2T requires Logix 5000 firmware v16 or higher on the controller. Rockwell recommends v20 or above for full DLR and CIP Security feature support. Verify the controller firmware revision in Studio 5000 before installation.

Q: Can the 1756-EN2T coexist with legacy communication modules in the same chassis?
A: Yes. The 1756-EN2T coexists with 1756-DHRIO, 1756-DNB, 1756-CNB, and other bridge modules in the same chassis, subject to chassis slot availability and total backplane power budget.

Warranty Assurance

Every 1756-EN2T module supplied by TOPNLMS is covered by a 12-Month Warranty from the date of shipment. Prior to dispatch, each unit undergoes functional verification including backplane communication testing, EtherNet/IP port integrity checks, and firmware revision confirmation. Modules are shipped in anti-static packaging with full traceability documentation.

In the event of a confirmed defect within the warranty period, TOPNLMS provides priority replacement dispatch to minimize production downtime. Our technical support team responds to after-sales inquiries within one business day, assisting with installation verification, firmware compatibility questions, and commissioning guidance. For B2B procurement teams managing multi-site ControlLogix deployments, we offer consolidated invoicing, advance replacement agreements, and volume pricing on spare-parts inventory programs.

Stock is maintained in Xiamen, China, with express international shipping available to most destinations. Lead times for in-stock units are typically 3–7 business days door-to-door for standard international freight, with expedited options available on request.