Modbus TCP Communication Issue Between MT8106iP and Arduino Opta PLC

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Modbus TCP Communication Issue Between MT8106iP and Arduino Opta PLC
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  • HMI Model: MT8106iP
  • EasyBuilder Pro Version: V6.10.02.284

Hello,

I am currently experiencing difficulties establishing communication between a Weintek MT8106iP HMI and an Arduino Opta WiFi PLC (model AFX00006). I am using the Modbus TCP/IP protocol to read and write data between the two devices; however, the HMI does not appear to receive any data from the PLC.

Both devices are configured with valid IP addresses on the same network, and basic connectivity (ping) is confirmed. Despite this, the HMI is unable to read the PLC’s Modbus registers.

If anyone has encountered a similar issue or can point out what I may be missing in the configuration, I would greatly appreciate your guidance. I am happy to provide additional details or screenshots of the setup if needed.

Thank you in advance for your assistance.

Noli Valdez

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Hi @Noli-Valdez ,

Thank you for contributing to our forum!

Could you please share some screen shots of your device settings within the system parameters? Also, would you advise the IP address of the Opta and HMI?

If you hadn’t had the chance to review our YouTube channel, here are some helpful tutorials on how to connect an Arduino Opta and Weintek HMI:

Weintek’s Codesys to Arduino Opta via Modbus RTU

Weintek HMI to Arduino Opta PLC using Modbus TCP/IP

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Thank you, Daniel, for the follow‑up. I identified the root cause, and it was unrelated to the IP configuration of either device. The issue was the runtime state of the OPTA PLC. When the PLC is in STOP mode and a project is downloaded to the controller, the HMI is unable to access or read any mapped tag variables over the network.