Hello, I have wroten an example programm and load on the rom of the microcontroller which makes the signal 1010101010 in an XON\XOFF -protocol of the function putchar in C. This signal will be send via RS232 to Com 1 of the PC where I've load the hyperterminal.The microcontroller and the hyperterminal are initialize on the same Baudrate and the same protocol,but the hyperterminal says nothing.Which mistake in logic have I made. Perhaps you can help me. Looking for your information Ingo Brockmann