A serial cable or RS-232 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 a ...
protocol. The form of connectors depends on the particular
serial port
A serial port is a serial communication Interface (computing), 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 Pa ...
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 data terminal equipment, DTEs (computer, computer terminal, terminal, printer (computing), printer, etc.) using an RS-232 serial cable. The name stems from the historical use of RS-232 ...
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 a digitally modulated signal or a line code, symbol rate, modulation rate or baud is the number of symbol changes, waveform changes, or signaling events across the transmission medium per unit of time. The symbol rate is measured in ''baud'' ...
on the cable, and the
capacitance
Capacitance is the ability of an object 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 two closely related ...
and
electrical impedance
In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of Electrical_resistance, resistance and Electrical_reactance, reactance in a electrical circuit, circuit.
Quantitatively, the impedan ...
of the cable. The
RS-232
In telecommunications, RS-232 or Recommended Standard 232 is a standard introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such as a compu ...
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 o ...
*
InterLnk
*
LapLink cable
Laplink (sometimes styled LapLink) is a proprietary software that was developed by Mark Eppley and sold by Traveling Software. First available in 1983, LapLink was used to synchronize, copy, or move, files between two PCs, in an era before local ...
(can be seen as a parallel equivalent to a serial
null modem
Null modem is a communication method to directly connect two data terminal equipment, DTEs (computer, computer terminal, terminal, printer (computing), printer, etc.) using an RS-232 serial cable. The name stems from the historical use of RS-232 ...
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 des ...
*
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 or roll over may refer to:
Arts and entertainment
* Rollover (film), ''Rollover'' (film), a 1981 American political thriller
*''Roll Over'', a 1992 album by Hound Dog (band), Hound Dog
* "Roll Over", a 2006 song by Zico Chain
* "Roll Ove ...
(also known as a “Yost” cable.)
*
USB adapter
References
Serial Cables pinouts and specificationsPinouts of various serial interfaces
{{DEFAULTSORT:Serial Cable
Telecommunications equipment