A serial cable is a
cable
Cable may refer to:
Mechanical
* Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof
* Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...
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 are ...
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
Null modem is a communication method to directly connect two DTEs (computer, terminal, printer, etc.) using an RS-232 serial cable. The name stems from the historical use of RS-232 cables to connect two teleprinter devices or two modems in orde ...
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 comp ...
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'') such a ...
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
This article presents a list of commands used by DOS operating systems, especially as used on x86-based IBM PC compatibles (PCs). Other DOS operating systems are not part of the scope of this list.
In DOS, many standard system commands were pro ...
*
LapLink cable A Laplink Cable, also known as ''null-printer'' cable, allows the connection of two computers via the parallel port to establish a direct cable connection.
The cable was introduced in 1983 with the Laplink software package, from Traveling Software ...
(can be seen as a parallel equivalent to a serial
null modem
Null modem is a communication method to directly connect two DTEs (computer, terminal, printer, etc.) using an RS-232 serial cable. The name stems from the historical use of RS-232 cables to connect two teleprinter devices or two modems in orde ...
cable)
*
Legacy port
In computing, a legacy port is a computer port or connector that is considered by some to be fully or partially superseded. The replacement ports usually provide most of the functionality of the legacy ports with higher speeds, more compact desi ...
*
Ethernet crossover cable
An Ethernet crossover cable is a crossover cable for Ethernet used to connect computing devices together directly. It is most often used to connect two devices of the same type, e.g. two computers (via their network interface controllers) or two ...
*
Rollover cable
Rollover cable (also known as a Yost cable, Cisco cable, or a Console cable) is a type of null-modem cable that is used to connect a computer terminal to a router's console port. This cable is typically flat (and has a light blue color) to help ...
(also known as a “Yost” cable.)
*
USB adapter
A USB-to-serial adapter or simply USB adapter is a type of protocol converter that is used for converting USB data signals to and from serial communications standards (serial ports). Most commonly the USB data signals are converted to either R ...
References
Serial Cables pinouts and specificationsPinouts of various serial interfaces
{{DEFAULTSORT:Serial Cable
Telecommunications equipment