If you are using Flash Magic for the download then:

1. Flash Magic won't work if another application such as uVision2 has the com port open. So if Flash Magic works then uVision2 isn't opening the com port at that point.

2. Flash Magic automatically closes the COM port when programming is complete. So you can switch between Hyperterminal and Flash Magic without having to close either program. You do have to manually disconnect and reconnect in hyperterminal however.

As to whether uVision2 opens a com port during debug, it usually does if you are using a monitor/debugger.

Andy
ESAcademy