If the port server software is unable to assign to the serial port, even though the serial port is available, ClearSCADA will detect an error and generate a 'Communications State - Failed: Assign to COM Port Failed' event. These errors are often caused by the port sharing feature being enabled for protocols that do not support sharing.
We recommend that you:
- Only enable sharing on those channels for which port sharing is supported and required. The following protocols support port sharing:
- Modbus RTU (including SCADAPack Modbus and SCADAPack RealFLO)
- Modbus ASCII
- DNP3
- IEC 60870.
You should disable port sharing on other channels (see Port Server for Port Sharing).
For additional help with assign to COM port failures, please contact Schneider Electric.