A serial cable is a
cable used to transfer information between two devices using a
serial communication
In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits a ...
protocol. The form of connectors depends on the particular
serial port
In computing, a serial port is a serial communication interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in parallel. ...
used. A cable wired for connecting two
DTEs directly is known as a
null modem cable.
Maximum cable lengths
The maximum working length of a cable varies depending on the characteristics of the transmitters and receivers, the
baud rate
In telecommunication and electronics, baud (; symbol: Bd) is a common unit of measurement of symbol rate, which is one of the components that determine the speed of communication over a data channel.
It is the unit for symbol rate or modul ...
on the cable, and the
capacitance
Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are ...
and
electrical impedance
In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit.
Quantitatively, the impedance of a two-terminal circuit element is the ratio of the c ...
of the cable. The
RS-232
In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' ('' data terminal equipment'') suc ...
standard states that a compliant port must provide defined signal characteristics for a capacitive load of 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.
See also
*
Direct cable connection
Direct Cable Connection (DCC) is a feature of Microsoft Windows that allows a computer to transfer and share files (or connected printers) with another computer, via a connection using either the serial port, parallel port or the infrared port ...
*
InterLnk
*
LapLink cable (can be seen as a parallel equivalent to a serial
null modem cable)
*
Legacy port
*
Ethernet crossover cable
*
Rollover cable (also known as a “Yost” cable.)
*
USB adapter
References
Serial Cables pinouts and specificationsPinouts of various serial interfaces
{{DEFAULTSORT:Serial Cable
Telecommunications equipment