Allen-Bradley 1756-EN2T EtherNet/IP Module

Description

Product Introduction & Engineering Value

The Allen-Bradley 1756-EN2T is a chassis-mounted ControlLogix EtherNet/IP communication module designed to connect controllers and ControlLogix systems with EtherNet/IP devices, remote I/O, and other industrial networks. It provides a single 10/100 Mbps RJ45 Ethernet interface and supports up to 128 TCP connections.

For maintenance teams, the important distinction is that this is not the older 1756-ENBT. Rockwell Automation identifies the 1756-EN2T as the functional replacement for the discontinued 1756-ENBT.

Technical Specifications

These values are based on Rockwell Automation’s current product specifications and installation documentation.

Firmware and Series Considerations

Do not treat every 1756-EN2T as firmware-equivalent. Rockwell’s Product Compatibility and Download Center lists multiple hardware series and firmware revisions, including Series C and Series D versions. The current download listing includes firmware version 12.002 for the 1756-EN2T.

A replacement should therefore be checked against the installed controller, Studio 5000/Logix environment, and existing Ethernet architecture before installation.

Field Application & The “Trench” Experience

A common maintenance scenario is an aging ControlLogix rack supporting a packaging or process line where the Ethernet communication module begins showing intermittent network faults. The controller itself continues executing its program, but remote I/O and supervisory communications become unreliable.

The maintenance team replaces the communication module with a matching 1756-EN2T, restores the original network configuration, verifies the firmware revision, and checks controller-to-I/O connections before returning the machine to production. The critical step is not simply plugging in another Ethernet module; the technician must verify the module revision and network configuration against the existing Logix project.

Specific application scenarios

• Distributed ControlLogix I/O on a high-speed packaging line where the EN2T provides the Ethernet bridge between the local chassis and remote EtherNet/IP devices.
• Process skid instrumentation networks where a ControlLogix controller exchanges cyclic and explicit messages with Ethernet-based field equipment.
• Legacy 1756-ENBT replacement projects, where the EN2T is used as the functional replacement identified by Rockwell Automation.

1756-EN2T

1756-EN2T

Transparency SOP: QA & Testing

For New Surplus or Refurbished 1756-EN2T inventory, a sensible incoming inspection sequence should include:

1. Visual inspection — Check the housing, RJ45 connector, label, chassis connector, indicators, and mechanical locking features for damage.
2. Identification verification — Confirm the catalog number, series, revision, and product labeling against the purchase specification.
3. Power-up test — Install the module in a compatible ControlLogix test chassis and verify normal startup behavior.
4. Ethernet test — Establish an EtherNet/IP connection and verify network communication.
5. Configuration test — Confirm module identification and communication parameters through the appropriate Rockwell Automation engineering environment.
6. Final inspection — Record test results and preserve serial/label information for traceability.

Rockwell Automation specifies a one-year standard warranty for the 1756-EN2T on its current product page; actual warranty terms for aftermarket New Surplus or Refurbished inventory should be stated separately by the supplier.

The Veteran’s Tech Trap Guide

⚠️ Trap #1 — Assuming every EN2T is interchangeable by firmware alone.
Series and firmware matter. Rockwell’s compatibility database shows different firmware branches for Series C and Series D hardware. Verify the installed system before committing to a replacement.

⚠️ Trap #2 — Confusing the EN2T with the EN2TR.
The catalog numbers are similar, but the network hardware is not identical. Do not substitute based solely on the “EN2” family designation.

⚠️ Trap #3 — Treating an Ethernet problem as a module problem.
Before replacing the EN2T, check the Ethernet cable, switch port, IP addressing, controller configuration, and connection status. A failed network connection does not automatically mean the communication module has failed.

PRO TIP: Record the original module’s catalog number, series, firmware revision, IP configuration, and Logix project settings before removing it. That information can save considerable commissioning time during an emergency replacement.

Dynamic FAQ

Is the 1756-EN2T an EtherNet/IP module?

Yes. The 1756-EN2T is a ControlLogix EtherNet/IP communication module with a 10/100 Mbps copper RJ45 interface.

How many TCP connections does the 1756-EN2T support?

Rockwell Automation specifies 128 maximum TCP connections and up to 256 CIP connections.

Can the 1756-EN2T replace a 1756-ENBT?

Rockwell Automation identifies the 1756-EN2T as the functional replacement for the discontinued 1756-ENBT. However, the actual replacement should still be checked against the existing application, firmware, and network configuration.

What should I verify when purchasing a 1756-EN2T?

At minimum, verify the catalog number, hardware series, firmware revision, physical condition, Ethernet interface, and warranty status. Series and firmware are particularly important for legacy ControlLogix installations.

How can I confirm that a New Surplus 1756-EN2T is authentic?

Check the physical catalog label and serial information, then compare the module identification against Rockwell Automation documentation and product resources. Rockwell’s own product page also provides product registration and verification functions.

What warranty is available?

Rockwell Automation currently lists a one-year standard warranty for the 1756-EN2T. For New Surplus or Refurbished units purchased through an independent supplier, confirm the supplier’s specific warranty terms before ordering.