Mitsubishi Electric LJ71E71-100-CM MELSEC L Series Ethernet Interface Module

Description

Providing high-speed Ethernet connectivity directly to MELSEC L Series architectures, the Mitsubishi Electric LJ71E71-100-CM manages robust plant-level data transmission and programming tasks. This module enables fast, reliable industrial network communications by acting as a gateway between the processor unit and supervisor-level SCADA systems, HMIs, or other controllers. Featuring dual-rate physical media support for 100BASE-TX and 10BASE-T networks, the module seamlessly processes intensive data payloads while maintaining low internal bus current draw. Built-in system functions allow for easy remote maintenance, diagnostic monitoring, and configuration changes directly through the GX Works2 programming software platform.

Features

• Multi-Protocol Support: Compatible with MELSOFT connection, SLMP (MC protocol), Socket communication, and pre-defined developer protocols.
• Flexible Network Access: Built-in Web functions and E-mail transmission utilities allow for direct remote troubleshooting and diagnostics.
• Auto-Negotiation: Built-in transceiver automatically adjusts between 100 Mbps and 10 Mbps operational speeds depending on the network switch environment.
• Compact L-Series Form Factor: Integrates directly onto the L-Series DIN-rail mount system without requiring a bulky dedicated base unit.

Applications

• Distributed industrial control networks linking multiple PLC systems across large manufacturing plants.
• Real-time communication and variables transmission between PLC units and HMI/SCADA management interfaces.
• Remote programming, diagnostic monitoring, and automated alarm notification via standard email services.

Technical Specifications

Connections and Interfaces

Empirical Engineering Insights

Alternative Models & Compatibility

The LJ71E71-100-CM is physically and functionally drop-in compatible with standard MELSEC L Series CPU systems. The "-CM" suffix indicates regional industrial standard compliance configurations, though identical Ethernet configurations apply inside GX Works2. In legacy migrations, verify your CPU unit firmware supports multi-connection network interfaces before integrating this module to prevent communication timeout faults.

Application Pitfalls & Engineering Notes

When adding the Ethernet module to an active L-Series CPU stack, recalculate your internal 5 VDC system bus current draw. This unit draws a constant 0.60 A. If combined with multiple positioning modules or high-density digital I/O blocks, you may exceed the current supply limit of standard power modules (such as the L61P or L63P), which can cause random CPU lockups or system reset faults.

Commissioning & Wiring Tips

To prevent high-frequency EMI noise from adjacent high-voltage machinery or VFD cabling from disrupting network communication packets, always use Category 5e (or higher) double-shielded twisted pair (STP) cables. Securely connect the cable shielding mesh directly to the system's protective ground bus and establish a single-point earth ground for the rack assembly.

Installation Guidelines