Skip to content

MELSEC LCPU — PLC-side settings

MELSEC LCPU — built-in Ethernet port (CPU module, 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

LCPU uses the GX Works2 MC Protocol open-setting flow used by the Q series.

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:

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

Built-in Ethernet port settings screen Built-in Ethernet port settings screen.

Built-in Ethernet port open settings screen Built-in Ethernet port open settings screen.