Modbus TCP read error

[seokgi]

I want to aggregate multiple devices operating via Modbus RTU serial and transmit data using Modbus TCP.

MCU: PIC24FJ512GA606

LAN: W5500

When checking in Modbus POLL, it does not work at all and only repeats read error and write error. If I delete the listen (502) from network comm in the main directory, a message appears stating that the server has closed it.

Please help.

[BenR]

Hello,

Sorry for the delay in getting back to you.

The NetworkComms1::Listen component macro call in main is not required.

I'll see if I can replicate the problem with the server socket being closed as this shouldn't be happening.

You could try changing the Modbus TCP component property "Open and Close Socket" to No and see if that helps.

[seokgi]

Modbus TCP component property "Open and Close Socket"

Do not support this option.

Thank you.

[BenR]

Here is the property I mean, If you don't have this maybe check the help -> library updates to see if there is a new version of the component.

Screenshot 2026-04-23 164335.png (53.58 KiB) Viewed 63 times