A serial cable is a cable that can be used to transfer information between two devices using serial communication. The form of connectors depends on the particular serial port used. A cable wired for connecting two data terminal equipments directly is known as a null modem cable.
The maximum working length of a cable varies depending on the characteristics of the transmitters and receivers, the baud rate on the cable, and the capacitance and resistance of the cable. The RS 232 standard states that a compliant port must provide defined signal characteristics for a capacitive load of 2500 pF. This does not correspond to a fixed length of cable since varying cables have different characteristics. Empirically tested combinations of bit rate, serial ports, cable type, and lengths may provide reliable communications, but generally RS 232-compatible ports are intended to be connected by at the most a few tens of metres of cable. Other serial communications standards are better adapted to drive hundreds or thousands of metres of cable
This cable has short transmission distance because of noise limiting the transmission of high numbers of bits per second when the cable is more than 15 meters long. This means that the transmitting and receiving lines are referenced to ground. It is cheap to purchase and is simple to join and connect. It is suitable for unbalanced data standards. Only one device can be connected to the cable.