To add to Craig's response, you may want to start with the sample code in http://support.microsoft.com/support/kb/articles/Q140/5/25.asp - HOWTO: Receive from the Serial Port by Using MScomm32.ocx.
Also useful may be http://support.microsoft.com/support/kb/articles/Q139/5/26.asp - HOWTO: Send to the Serial Port by Using Mscomm32.ocx.
And of course, http://support.microsoft.com/support/kb/articles/Q154/7/41.asp - HOWTO: Transmit and Receive Binary Data using MSCOMM32.

Rick

>Hi,
>
>Don't you know about 'any good class/prg' for communication with serial port ?
>
>I need read/write from/to special PC system.
>
>Thanks.