As a modbus master with the M340 (Schneider Electric) system, I have experienced smooth operation. However, when a disconnection occurs with the slave device, the system stops functioning even after the connection is restored. The only solution I have found is to restart the PLC. Is there a method to reset only the communication function without halting the PLC operations?
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To ensure proper function of the Read or Write function in the GEST array, it is crucial to set a nonzero timeout value beforehand. Failing to do so may result in the function never timing out, even if the GEST time is adjusted post-trigger. In such cases, a power cycle of the PLC is necessary.
It seems like your Modbus Master isn't able to recognize when the connection to the slave device is reestablished. Rather than restarting the entire PLC, you might want to consider implementing a communication watchdog system. By constantly checking the status of the communication link, it can detect when the connection is lost and subsequently restored, and reset the communication function accordingly. This can help your system to recover without affecting the ongoing operations of the PLC. I've known a few folks who had similar issues and this solution worked well for them.
I experienced a similar issue in the past. What seemed to solve the problem for me was creating a function in the PLC programming where I constantly checked the status of connection with the slave device. If the connection failed, I would execute a short routine that resets the communication port. This allowed the PLC operations to continue without noticeable interruption. You might want to experiment with this solution and see if it works for your setup. Keep in mind that the resetting routine needs to be configured carefully to not overload the PLC resources.
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Answer: 1. Q: What can be done when a disconnection occurs with the slave device in Modbus communication with M340 PLC? When a disconnection occurs, try resetting the communication function without halting the PLC operations by following specific procedures or utilizing certain features.
Answer: Explore methods to reset only the communication function without requiring a full PLC restart, ensuring smoother operation even after re-establishing the connection with the slave device.
Answer: Consider troubleshooting steps such as identifying potential causes of disconnections, checking configurations, and exploring ways to reset the communication function to resolve issues without stopping PLC operations.
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