RS-423
Encyclopedia
| RS423 | |
|---|---|
| Standard | EIA RS-423 |
| Physical Media | Group of Copper cables |
| Network Topology | Point-to-point, Multi-dropped |
| Maximum Devices | 10 (1 driver & 10 receivers) |
| Maximum Distance | 1200 metres (4000 feet) |
| Mode of Operation | Single Ended (Unbalanced) |
| Maximum Baud Rate | Up to 100Kbps |
| Voltage Levels | -6V to +6V (maximum Voltage) |
| Mark(1) | -4V to -6V |
| Space(0) | +4V to +6V |
| Available Signals | Tx, Rx & GND |
RS/EIA/TIA-423 is a standard for serial communication
Serial communication
In telecommunication and computer science, 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 sent as a whole, on a link with several parallel channels...
s. It defines an unbalanced (single-ended
Single-ended signalling
Single-ended signaling is the simplest and most commonly used method of transmitting electrical signals over wires. One wire carries a varying voltage that represents the signal, while the other wire is connected to a reference voltage, usually ground....
) interface (similar to RS-232
RS-232
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 DTE and a DCE . It is commonly used in computer serial ports...
), with a single, unidirectional sending driver, and allows for up to 10 receivers (similar to RS-422
EIA-422
RS-422 is a technical standard that specifies electrical characteristics of a digital signalling circuit. Differential-mode signals can be sent at rates as high as 10 million bits per second, or may be sent on cables as long as 1200 metres. Some systems directly interconnect using RS 422 signals,...
). It is normally implemented in integrated circuit technology and can also be employed for the interchange of serial binary signals between DTE
Data terminal equipment
Data Terminal Equipment is an end instrument that converts user information into signals or reconverts received signals. These can also be called tail circuits. A DTE device communicates with the data circuit-terminating equipment...
& DCE
Data circuit-terminating equipment
A data circuit-terminating equipment is a device that sits between the data terminal equipment and a data transmission circuit. It is also called data communications equipment and data carrier equipment...
. There is no common pinout
Pinout
In electronics, a pinout is a cross-reference between the contacts, or pins, of an electrical connector or electronic component, and their functions.- Purpose :...
for RS-423. The BBC Micro
BBC Micro
The BBC Microcomputer System, or BBC Micro, was a series of microcomputers and associated peripherals designed and built by Acorn Computers for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation...
computer used a 5-pin DIN connector
DIN connector
A DIN connector is a connector that was originally standardized by the , the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless...
. DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
used it extensively with a Modified Modular Jack
Modified Modular Jack
The DECconnect Modified Modular Jack is a variation of the 6P6C modular connector and was developed by Digital Equipment Corporation. The main difference from the conventional modular connector is that the hook is toward the side instead of the center of the plug, making it impossible to insert a...
connector. This was sometimes called "DEC-423".
Use of a common ground is one weakness of RS-423 (and RS-232
RS-232
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 DTE and a DCE . It is commonly used in computer serial ports...
): if devices are far enough apart or on separate power systems, the ground will degrade between them and communications will fail, resulting in a condition that is difficult to trace. In this respect the balanced serial connections USB, RS-422 and RS-485 are better, and Ethernet over twisted pair
Ethernet over twisted pair
Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. Other Ethernet cable standards employ coaxial cable or optical fiber. Early versions developed in the 1980s included StarLAN followed by 10BASE-T. By the 1990s, fast, inexpensive...
connections are better yet, because of the galvanic isolation
Galvanic isolation
Galvanic isolation is a principle of isolating functional sections of electrical systems, thus preventing the movement of charge-carrying particles from one section to another, i.e. no direct current flows between the sections. Energy or information can still be exchanged between the sections by...
provided by the signal transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
s.
See also
- Electronic Industries AllianceElectronic Industries AllianceThe Electronic Industries Alliance was a standards and trade organization composed as an alliance of trade associations for electronics manufacturers in the United States. They developed standards to ensure the equipment of different manufacturers was compatible and interchangeable...
- RS-232RS-232In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...
- RS-485
- ProfibusProfibusPROFIBUS is a standard for field bus communication in automation technology and was first promoted in 1989 by BMBF...
- FieldbusFieldbusFieldbus is the name of a family of industrial computer network protocols used for real-time distributed control, now standardized as IEC 61158....
- List of network buses