ClearSCADA will detect a communications failure if a channel attempts to use a serial port that is already being used by another application or channel. In such circumstances, ClearSCADA will add a 'Failed: COM port already assigned' event to the Events List.
Common causes of 'Failed: COM port already assigned' statuses are:
- A shared channel and a non-shared channel both being assigned to the same serial port
- 2 or more dial-in channels being used when sharing a modem
- The port settings for one or more channels being different when the port is a shared port. The port settings for each of the channels that share the port has to be identical.
- There are multiple channels of the same protocol type set up to share the same serial port. There can only be 1 channel per protocol for a shared port.
We recommend that you either:
- Change the channel configuration so that it defines a different serial port or uses a different protocol. (For more information, refer to the driver specific documentation).
- Change the other application (on the remote computer) or other ClearSCADA channel so that it uses a different serial port.