Hey,
I have a problem with my UART. It runs as long as the RS232-Cable to the PC is connected, but once I unplug it(i.e. the TxD and RxD Pins are open), the UART stops sending data. Is this a correct behaviour or am I doing something wrong?
Not much information here.
Are you metering the UART on the uC directly, an external UART, or a line driver like the MAX232 to translate CMOS or TTL into the RS232 voltages?
Like erik has mentioned, your code may be designed in such a way that without received data, it will never transmit anything.
Your external hardware may be using hardware flow control like RTS/CTS, and the CTS line on the non-PC side is just floating.