I'm facing a weird issue with CODESYS Control Win V3 x64 on a fresh Windows install.
The situation is as follows:
CODESYS Modbus TCP Server (Slave) is running and I can see live values in the mapping display of Modbus settings: GVL (e.g., 32, 42, 50).
Port 502 is LISTENING according to netstat.
When connecting via Modbus Poll or Node-RED, the connection status changes to ESTABLISHED and everything reports as fine.
The Problem: Despite the successful connection, all holding registers return 0 no matter what. It's like the OS accepts the TCP handshake, the request counter goes up but the data payload never reaches Modbus Client (in this case Node-RED or Modbus Poll).
Quick Stats:
Firewall: Completely OFF.
Unit ID: Verified & Matching.
IP: Tried 127.0.0.1 and 192.168.0.1.
Interface: Correctly bound in Ethernet Device settings.
I already tried absolutely everything from changing IP address, subnet, port, deleting the project and starting new one and even nuking my old Windows install. Since I am near completion of my bachelor thesis only thing left for me to do is connect SoftPLC to NodeRED via Modbus but this issue is driving me crazy for weeks. I do not know what to do anymore.
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Hello everyone!
I'm facing a weird issue with CODESYS Control Win V3 x64 on a fresh Windows install.
The situation is as follows:
CODESYS Modbus TCP Server (Slave) is running and I can see live values in the mapping display of Modbus settings: GVL (e.g., 32, 42, 50).
Port 502 is LISTENING according to netstat.
When connecting via Modbus Poll or Node-RED, the connection status changes to ESTABLISHED and everything reports as fine.
The Problem: Despite the successful connection, all holding registers return 0 no matter what. It's like the OS accepts the TCP handshake, the request counter goes up but the data payload never reaches Modbus Client (in this case Node-RED or Modbus Poll).
Quick Stats:
Firewall: Completely OFF.
Unit ID: Verified & Matching.
IP: Tried 127.0.0.1 and 192.168.0.1.
Interface: Correctly bound in Ethernet Device settings.
I already tried absolutely everything from changing IP address, subnet, port, deleting the project and starting new one and even nuking my old Windows install. Since I am near completion of my bachelor thesis only thing left for me to do is connect SoftPLC to NodeRED via Modbus but this issue is driving me crazy for weeks. I do not know what to do anymore.
Are you sure you need to read holding registers? Have you tried reading input registers?