This excludes, as buses, schemes such as serial RS-232, parallel Centronics, and IEEE 1284 interfaces, and Ethernet, since devices also needed separate power supplies.

An RS-232 port was once a standard feature of a personal computer for connections to modems, printers, mice, data storage, uninterruptible power supplies, and other peripheral devices.

Some RS-232 devices are still found, especially in industrial machines or scientific instruments.

RS-232 makes no provision for power to peripheral devices.

Since the requirements of devices such as computers, printers, test instruments, POS terminals and so on were not considered by the standard, designers implementing an RS-232 compatible interface on their equipment often interpreted the requirements idiosyncratically.

USB is more complex than the RS-232 standard because it includes a protocol for transferring data to devices.

The ZX Interface 1 add-on module included 8 kB of ROM, an RS-232 serial port, a proprietary LAN interface ( called ZX Net ), and an interface for the connection of up to eight ZX Microdrives – somewhat unreliable but speedy tape-loop cartridge storage devices released in July 1983.

A null modem reroutes wiring so that two serial devices may connect directly to one another without any communications hardware ( see RS-232 ).

When two devices, that are both DTE or both DCE, must be connected together without a modem or a similar media translator between them, a crossover cable must be used, e. g. a null modem for RS-232 or an Ethernet crossover cable.

Perhaps the final 7-bit restriction, primarily imposed due to the pervasive use of RS-232 protocol for serial ports between devices, notably computers and modems, was lifted in the mid-1990s when RS-232 was largely replaced with Ethernet and with USB.

Inter-operation with RS-232 devices may be impossible as the serial port cannot withstand the voltage levels produced and may have other differences that " lock in " the user to products of a particular manufacturer.

Stratum-0 devices are traditionally not attached to the network ; instead they are locally connected to computers ( e. g., via an RS-232 connection using a pulse per second signal ).

Although the Series / 1 uses EBCDIC character encoding internally and locally attached EBCDIC terminals, ASCII based remote terminals and devices could be attached via an I / O card with a RS-232 interface to be more compatible with competing minicomputers.

Examples include RS-232 and lower-end SCSI devices.

RS-232 devices originally used the DB25, but for many applications the less common signals were omitted, allowing a DE9 to be used.

The name stems from the historical use of the RS-232 cable to connect two teleprinter devices to modems in order to communicate with one another ; null modem communication was possible by instead using RS-232 to connect the teleprinters directly to one another.

Midnight Commander is based on versatile text interfaces, such as Ncurses or S-Lang, which allow it to work on a regular console, inside an X Window terminal, over SSH connections, RS-232 interface ( for embedded devices ) and all kinds of remote shells.

An obvious solution was to use the RS-232 serial port ; modems were serial devices and generally driven off RS-232 anyway, and most computer designs included an RS-232 port, or some variant.

Other possible inclusions are energy harvesting modules, secondary ASICs, and possibly secondary communication devices ( e. g. RS-232 or USB ).

Breakout boxes are specific examples of a more general category of network testing equipment called “ status monitors .” A variety of these monitoring devices are available for testing serial interfaces, including RS-232, RS-449, V. 35, and X. 21, as well as specialty interfaces.

Devices that convert USB to RS-232 may not work with all software on all personal computers and may cause a reduction in bandwidth along with higher latency.

These also protect the device's internal circuitry from short circuits or transients that may appear on the RS-232 interface, and provide sufficient current to comply with the slew rate requirements for data transmission.

Modern meters may be interfaced with a personal computer by IrDA links, RS-232 connections, USB, or an instrument bus such as IEEE-488.

Small-form-factor systems and laptops may omit RS-232 connector ports to conserve space, but the electronics are still there.

It could be expanded with RAM ( memory ) and ROM ( software ) modules, as well as peripherals like bar code readers, microcassette and floppy disk drives, paper-roll thermal printers, and miscellaneous communication interfaces ( RS-232, HP-IL, HP-IB ).

On connections over RS-232 Statistical Multiplexers where some control characters do not transmit, Kermit can be configured to work, unlike protocols like XMODEM that require all 256 bytes be transmittable.

When electronic terminals ( smart and dumb ) began to be used, they were often designed to be interchangeable with teletypewriters, and so supported RS-232.

RS-232 drivers and receivers must be able to withstand indefinite short circuit to ground or to any voltage level up to ± 25 volts.

External RS-232 / 485 converters or internal RS-485 cards have to be installed as standard PCs do not have RS-485 communication ports.

Iridium 9500, 9505 and 9505A phones can be connected to computers using an RS-232 connection, as can the 9522A transceiver module.

Finally, there was the Synertek SYM-1 variant, which could be said to be a machine halfway between the KIM and the AIM ; it had the KIM's small display, and a simple membrane keyboard of 29 keys ( hex digits and control keys only ), but provided AIM-standard expansion interfaces and true RS-232 ( voltage level as well as current loop mode supported ).

Power supplies on the bus were unregulated + 8 V and ± 18 V, designed to be regulated on the cards to + 5 V ( used by TTL ) and ± 12 V ( typically used on RS-232 lines or disk drive motors ).

To automate outbound calls, a separate peripheral device, a " dialer ", could be plugged into a different input / output port on the computer ( typically an RS-232 port ).

Communication ports These included two 25-pin RS-232 serial ports ( including one intended for a Xerox 620 or 630 printer or compatible ), and two optional parallel ports which could be added via an internal pin header, usable with a Xerox-supplied or other cable.

Although the existing serial ports could be adapted to run in " AV mode " in the same fashion that the older versions could run in RS-232 or networking mode, the line adaptor required more power that the port could supply.

Another more advanced method is to attach a TTL to the modem's RS-232 adapter, and get access to the modem's console directly to make it download new firmware, which can then be configured via a simple web interface.

Each teleprinter would be physically connected to its modem via an RS-232 connection and the modems could call each other to establish a remote connection between the teleprinters.

In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a < span title =" Usually a controlling terminal or a computer "> DTE </ span > ( Data Terminal Equipment ) and a < span title =" Usually a modem or target device "> DCE </ span > ( Data Circuit-terminating Equipment ).

Typically Wiegand protocol is used for transmitting data to the control panel, but other options such as RS-232, RS-485 and Clock / Data are not uncommon.

Data transmission is utilized in computers in computer buses and for communication with peripheral equipment via parallel ports and serial ports such us RS-232 ( 1969 ), Firewire ( 1995 ) and USB ( 1996 ).

Short Burst Data applications are supported through an RS-232 interface.

* Data Carrier Detect, a term used with modems and the RS-232 interface

* Data Set Ready-An RS-232 signal used by a modem to indicate to the computer that it is ready to receive data.

* The SDP-The Synchronous Data Processor-added V. 35, RS-422, and RS-232 data to the IPX ( this card was a very early use of Xilinx FPGAs & StrataCom was their largest customer for a time )

* Data Terminal Ready: A control line used in RS-232 serial communications to indicate that the computer is ready to receive data.