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SerialPort Control in VC# Express 2005


I have a problem with the SerialPort Control under VC# Express 2005.
In my application I have to read data from an external device through RS 232.
The process is built on a software-based handshaking which depends on the

The process has been implemented by me and works but unfortunately only the
first time.
All data are donwloaded successfully as required.
The process is simple serialPort11.Op en(), Handshaking, Data Download,
Handshaking, serialPort1.Clo se().

The problem occurs with the second run, when the same procedure is executed
again (using a button_onclick event), then the Port is opened again with
serialPort1.Ope n() and with the first serialPort1.rea dByte() a TimeOut Error
Even if the Timeout is set to 10sec it does not help.

If the application is restarted and the process is again executed, then the
data are read perfectly from the device. Hence it does not depend on the
state of the external device, but on the PC (Soft and/or Hardware).

I have the feeling, that closing the SerialPort with serialPort1.Clo se()
does not free all resources and possibly the hardware RS232 is not fully

Has anyone had a similar problem and found a solution for it?
Can you rely on serialPort1.Clo se()? Are all resources freed?

I hope someone can help

Thanks a lot in advance
Best regards,


Jul 18 '06 #1
0 1395

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