RS–232C is a serial communication standard that connects a computer to external peripherals, such as modems. It was commonly used for computer interfaces before the prevalence of LAN and USB. Communication speeds include 2400 and 9600 bps. Because the communication lines are single-ended rather than differential signals, the communication distance is short and vulnerable to noise. Furthermore, it is limited to one link per port because the number of connections is 1:1.
Communication depends on the alignment of communication speed (bits per second, bps); data bits; parity; stop bits; flow control;  and other device settings.