Allen-Bradley 1756-EN3TR Ethernet Communication Module

Configured for deterministic industrial communications in ControlLogix systems, the Allen-Bradley 1756-EN3TR (1756-EN3TR) Ethernet Communication Module provides direct physical/electrical execution of high-speed data transfer and integrated motion control across ControlLogix platforms.

Hardware Specifications

Profinet / EtherNet/IP Deterministic Networks

The 1756-EN3TR maintains network determinism through support for Linear and Device Level Ring (DLR) topologies, allowing for fault-tolerant communication architectures. The module supports data transfer rates of 10/100 Mbps on Ethernet ports and 12 Mbps via the USB configuration port. Firmware flash compatibility between the communication module and the ControlLogix processor is required to ensure synchronized motion axis control for up to 128 axes. I/O density scaling must be monitored when managing high-volume data traffic to ensure the backplane bus communication velocity remains sufficient to prevent packet loss or jitter in time-critical control loops.

Frequently Asked Questions

Q: Can this module be hot-swapped while the ControlLogix chassis is powered?

A: Yes, the 1756-EN3TR supports insertion and removal under power (RIUP) in a ControlLogix chassis. However, doing so will temporarily interrupt communication to all nodes managed by this specific module.

Q: Is the USB port intended for continuous process data acquisition?

A: No. The USB port is strictly intended for local configuration, firmware updates, and troubleshooting. It is not designed to support continuous, high-latency industrial network traffic.

Field Installation Guidelines

1. Ensure the module is seated fully into any available slot in a 1756 chassis and that the locking latch is engaged to maintain backplane connectivity.
2. For DLR topologies, connect the Ethernet ports in a ring configuration to ensure network redundancy.
3. Use only shielded, Category 5e or higher Ethernet cabling to meet electrical noise immunity standards in industrial environments.
4. Route all communication cabling through dedicated conduits or wireways, maintaining a minimum separation of 150 mm from high-voltage power cabling to avoid EMI.
5. Verify that the chassis power supply is rated to handle the additional 1.0 A current draw of the 1756-EN3TR to prevent voltage sags on the backplane.
6. Observe the front-panel status LEDs after installation; a steady green status confirms successful backplane communication and processor recognition.