The error message “could not open serial port” is not a Dynamic C error message. The error is caused by not opening the correct port that is attached to your product, or the serial port you are selecting is in use by another application. Try closing all other applications that may use that serial port.
The error "Could not open serial port", means that you do not have the correct comm port selected in Projects. Go to "Options" -> "Project Options" -> on the Communications Tab, choose the correct "Serial Port" under "Serial Options".
Jun 11, 2019