1756-EN4TR — 1756 EtherNet/IP Communication Module, 1 Gbps, Dual-Port

The 1756-EN4TR is a 1 Gbps EtherNet/IP communication module for the 1756 chassis. It provides the controller with two independent 1000 Mbps Ethernet ports and supports Device Level Ring (DLR) topology, making it the high-bandwidth option for controller-to-network communication in demanding applications — large-scale I/O systems, high-density CIP Motion architectures, and redundant network designs where the single-port 100 Mbps EN2T has reached its capacity ceiling.

The step from 100 Mbps (EN2T) to 1 Gbps is a 10× bandwidth increase. In most standard I/O and HMI systems, 100 Mbps has enough headroom that the upgrade adds little practical benefit. Where 1 Gbps matters is in systems with hundreds of I/O devices on a single EtherNet/IP connection, multiple simultaneous CIP Motion axes with short RPIs, or large explicit message volumes from diagnostic-intensive field devices. These are applications where 100 Mbps bandwidth starts to become a constraint.

Specifications

Parameter	Value
Part Number	1756-EN4TR
Platform	1756 Logix chassis
Ethernet Speed	1000 Mbps (1 Gbps) per port
Ethernet Ports	2 × RJ-45 (10/100/1000 Mbps auto-negotiate)
Topology Support	Linear, Star, Device Level Ring (DLR)
DLR Role	Ring supervisor or ring node
Max Concurrent CIP Connections	500+
EtherNet/IP Messaging	Class 1 (cyclic I/O), Class 3 / UCMM (explicit)
Redundancy Support	Yes (with 1756-RM redundancy module)
Backplane Current (5V)	1.25 A
Operating Temperature	0°C to 60°C
Standards	EtherNet/IP Conformance Tested, UL 508, CE

1 Gbps in the 1756 Chassis

The EN4TR's 1 Gbps ports deliver full gigabit throughput to connected devices. For this to matter, both ends of the connection need to be running at 1 Gbps — connecting a 1 Gbps module to a 100 Mbps switch or a 100 Mbps I/O device won't produce gigabit speeds at that segment. The practical upgrade is on the uplink: an EN4TR connected to a gigabit managed switch over a gigabit uplink cable gives the controller a 1 Gbps path to the rest of the network infrastructure, even if downstream field devices are 100 Mbps.

The higher connection capacity is equally important. The EN4TR supports over 500 concurrent CIP connections, compared to the 128–256 connections of older modules. Each EtherNet/IP I/O device, HMI, and drive consumes at least one connection; large systems with dozens of remote I/O nodes and multiple drives can exhaust the connection limit on older modules long before they saturate the bandwidth. The EN4TR's connection capacity addresses this directly.

EN4TR vs. EN2T — Choosing the Right Module

Both modules put the 1756 chassis on an EtherNet/IP network. The practical decision comes down to a few questions:

How many EtherNet/IP connections does the system need? Count remote I/O adapters, drives with EtherNet/IP cards, HMIs, and any peer-to-peer messaging connections. If the total approaches or exceeds the EN2T's 128–256 connection ceiling, the EN4TR's 500+ capacity is the right choice.
Is CIP Motion with many axes and short RPIs (under 2 ms) in the system? High-density servo motion systems benefit from gigabit bandwidth to reduce communication jitter. For 1–4 axis systems with standard RPIs, EN2T is fine.
Is a gigabit network infrastructure already in place? If the plant network is running gigabit switches and 1 Gbps Ethernet connections, the EN4TR can use that infrastructure directly. If everything is still 100 Mbps, the bandwidth difference is less relevant at the controller level.
Is controller-level redundancy planned? Both modules support 1756 redundancy, but verify the specific firmware requirements for the redundancy configuration in use.

FAQ

Q: Does using the EN4TR require any changes to the Studio 5000 project compared to an EN2T?

The I/O configuration and tag addressing are identical — the EN4TR appears as an EtherNet/IP module in the controller's I/O tree the same way any other communication module does. No programming changes are required when upgrading from EN2T to EN4TR, beyond updating the module catalog number in the I/O configuration.

Q: Can both Ethernet ports on the EN4TR be connected to different network segments?

No. Both ports share one IP address and one network connection. They function as a two-port DLR-capable switch within the module — both ports are on the same subnet. One port can be an uplink to a managed switch; the second can connect to a DLR ring or a downstream device. They cannot bridge different subnets.

Q: Is a Cat6 cable required for 1 Gbps operation, or will Cat5e work?

Cat5e supports 1 Gbps (1000BASE-T) at cable lengths up to 100 m. Cat6 provides better noise margin and is preferred for new installations, but properly installed Cat5e runs will operate at 1 Gbps without issues in most industrial environments.

Q: How many EN4TR modules can be installed in one 1756 chassis?

There's no fixed limit imposed by the module itself — the practical limits are backplane current draw (1.25A at 5V per module) and available chassis slots. Most applications use one or two EtherNet/IP modules per chassis. For large multi-network systems, multiple EN4TR modules each managing a separate EtherNet/IP network segment is a valid architecture.

1756-EN4TR Brand New 1756EN4TR EtherNet/IP Communication Module