MELSEC LJ71E71-100 — PLC-side settings

MELSEC LJ71E71-100 — Ethernet communication unit for L series.

What you need

• Configuration tool: GX Works2
• Network: Align IP address, subnet mask, and default gateway with your network environment.
• After configuration: Power cycle the PLC to apply the new parameters.

Example values used in this guide

Parameter	Example value	Notes
IP address	192.168.250.100	Adapt to your network
TCP port	1025	MC Protocol / SLMP TCP
UDP port	1035	MC Protocol / SLMP UDP

PLC-side settings

Use the LJ71E71-100 when the L series CPU does not have a built-in Ethernet port. Settings and profile are identical to the LCPU built-in port.

Screen: Built-in Ethernet port settings

Parameter	Setting
IP Address	192.168.250.100 (example)
Subnet Mask	Match your network
Default Gateway	Match your network
Communication Data Code	Binary code communication
Write During RUN	Enabled (FTP and MC protocol)

Screen: Built-in Ethernet port open settings

#	Protocol	Open Method	Local Port
1	TCP	MC Protocol	1025
2	UDP	MC Protocol	1035

Connecting with this library

Parameter	Value
Canonical profile	melsec:lcpu
Port (TCP)	1025
Port (UDP)	1035

Code example:

Python.NET (C#)

import asyncio

from slmp import SlmpConnectionOptions, open_and_connect, read_typed


async def main() -> None:
    options = SlmpConnectionOptions(host="192.168.250.100", port=1025, plc_profile="melsec:lcpu")
    async with await open_and_connect(options) as client:
        value = await read_typed(client, "D100", "U")
        print(f"D100={value}")


asyncio.run(main())

using PlcComm.Slmp;

var options = new SlmpConnectionOptions("192.168.250.100", SlmpPlcProfile.LCpu) { Port = 1025 };
await using var client = await SlmpClientFactory.OpenAndConnectAsync(options);
var value = await client.ReadTypedAsync("D100", "U");
Console.WriteLine($"D100={value}");

Screenshots

LJ71E71-100 Ethernet unit settings screen.

LJ71E71-100 network parameter screen.

LJ71E71-100 open settings screen.

LJ71E71-100 MC Protocol open setting details.