Kepware Knowledge Base: Solution
Resolving 'Communications error on COMn [***O***]'
Last Update: 11/12/2018
Possible Cause:
This is a character buffer overrun error.
Solution:
To resolve the error, refer to the instructions below.
- Open the Windows Device Manager. Then, click Ports | <the COM port in question> | Port Settings | Advanced.
- Next, decrease the Receive Buffer one notch from the maximum.
- Restart the computer. The new setting will not take effect until the computer has been restarted.
- Continue to decrease the Receive Buffer until the buffer overruns stop occurring.
Note: Do not automatically set the Receive Buffer to 1. It needs to be as high as possible without causing buffer overruns.
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