If the mode is set to 422, the echo setting will take no effect. This connection is commonly used for securitysurveillance video cameras to control the pantiltzoom available from pelco or others, or to connect displays for signage indoors or outdoors, clock displays, etc. Configuration for rs422 interface devices, usually three types of configurations are commonly used. This, and the fact that baud rate, parity, number of stop bits, number of data bits are programmable is the reason why uarts are called universal. Rs 422 vs rs 485 similarities and key differences 1. Throughout this document the generic terms of rs422 and rs485 are used when referring to equipment and. Maxim offers over 160 rs485rs422 transceivers for applications such as automotive, hvac, metering, and point of sale pos. An example of a pullup and a pulldown resistor on an rs485 bus to ensure the proper voltages on an inactive bus. The driver or generator is labeled d, the receiver is labeled r, and the termination impedance is zt. The icusb422 6ft professional rs422485 usb serial cable adapter with com port retention lets you connect rs422 or rs485 serial devices to your usbenabled computer. These monolithic quadruple differential line drivers with 3state outputs are designed to meet the requirements of ansi standards eiatia 422 b and rs 485 and itu recommendation v. These devices are designed specifically for applications meeting the st506, st412 and esdi disk drive standards. Many rs422 drivers always maintain control of the bus, which means they always produce voltages on their outputs. The max483, max487, max488, and max489 feature reduced slewrate drivers that minimize emi and reduce reflections caused by improperly terminated cables.
The full duplex adm4854 adm4855adm4856 adm4857 transceivers have dedicated differential line driver outputs and receiver inputs. Additionally up to ten receivers can be placed on a single cable, providing a multipoint network or bus. We say that rs485 devices are backward compatible with rs422 networks. A balanced differential line receiver senses the voltage state of the transmission line across. Sep 08, 2015 the terminations are placed at the driver and receiver farthest from each other. Eia485 devices may be used in 422 circuits, but eia422 may not be used in 485 circuits because of the lack of an enable line. Features, specifications, alternative product, product training modules, and datasheets are all available. This line driver receiver does not necessarily need to be an rs 232 line driver receiver, but could e. It was intended to replace the older rs232c standard with a standard that offered much higher speed, better immunity from noise, and longer cable lengths. High end gps receiver with twisted air cable rs422 for boat, ship usable with plotter, radio, fishfinder, etc please be sure that you can connect rs 422. Rs422 is also designated for multidrop partyline communication applications where there is only one driver connected to and transmits on, a bus of up to 10 receivers. Since both rs 422 and rs 485 are data transmission systems that use balanced differential signals, it is appropriate to discuss both systems in the same publication. Uart is short for universal asynchronous receiver transmitter, and ttl stands for transistor to transistor logic.
General description the ad7306 line driverreceiver is a 5 v monolithic product which provides an interface between ttl signal levels and dual standard eia rs232rs422 signal levels. To enable the differential driver to be used, the rs422 standard uses a four conductor cable. The sn65hvd379 is a differential line driver and differentialinput line receiver that operates with a 3. Since both rs422 and rs485 are data transmission systems that use balanced differential signals, it is.
The part contains two rs232 drivers, one rs422 driver, one rs232 receiver, and one receiver path which can be configured either as rs232 or as rs422. It supports data rate from 100 kbps to about 10 mbps. The driver and receiver feature threestate outputs, with the driver outputs maintaining high. Usb serial adapter usb to rs422 usb to rs485 9 pin. Antenna with waterproof, antiuv, antiacidity and antialkalinity protection. Rs485rs422 transceivers general description the sp3070e sp3078e differential line transceivers are suitable for bidirectional communication on balanced multipoint bus transmission lines and comply with both rs485 and rs422 eia standards. Rs 485 transceivers are available in both industrystandard packages and small, spacingsaving packages. The ad7306 line driver receiver is a 5 v monolithic product which provides an interface between ttl signal levels and dual standard eia rs 232 rs 422 signal levels. February 2009 rev 16 119 19 st485b st485c low power rs 485rs 422 transceiver features low quiescent current. Rs 422 key parameters and topology rs 422 is a unidirectional, multidrop network, allowing for the use of a single driver with an output signal that can be dropped at multiple up to 10 receiver nodes see figure1. These devices include failsafe circuitry, guaranteeing a logichigh receiver output when receiver inputs are open or shorted. Rs422, also known as tiaeia422, is a technical standard originated by the electronic. A device with an rs 485 or rs 422 port might include a builtin termination resistance you can connect to a bus if needed or leave disconnected. Low power rs485rs422 transceiver stmicroelectronics.
Usb serial adapter usb to rs422 usb to rs485 9 pin db9. System bus frontside bus backside bus daisy chain control. Integrated cable termination and four configuration modes allow all three protocols to be used interchangeably. This means that the receiver output will be a logic high if all transmitters. Figure depicts rs 422 pin configuration for 9 pin connector. View more information about our rs 485 rs 422 transceivers by category. It was intended to replace the older rs 232c standard with a standard that offered much higher speed, better immunity from noise, and longer cable lengths. General description the max481, max483, max485, max487max491, and. Rs422, rs485 differential line driver texas instruments.
Rs422, rs485 receivers maxim integrated rs422, rs485. Eiatia422 defines a balanced differential interface. The lowpower, highspeed transceivers of this family are designed for rs485, rs422 and rs423 communication applications. The ds96176 combines a tristate differential line driver and a differential input line receiver, both of which operate from a single 5. Ds8922ds8922ads8923a tristate rs422 dual differential. That means you can add an rs485 receiver to an rs422 bus, but you cannot put an rs485 driver on an rs422 bus that already has a driver. Integrated cable termination and four configuration modes allow all.
Rs 422 will support pointtopoint, and multidrop circuits, but not multipoint. These devices feature failsafe circuitry, which guarantees a logichigh receiver output when the receiver inputs are open or shorted. Rs422 interface rs422 pin diagram rf wireless world. Throughout this document the generic terms of rs 422 and rs 485 are used when referring to equipment and. They usually contain one driver and one receiver in half duplex configuration. The configuration of the sp336e can be reconfigured into eight operating. Rs422 systems can transmit data at rates as high as 10. Pointtopoint configuration first, pointtopoint, is a one driver and one receiver system. The transceiver operates at data rates up to 20mbps, with an output skew of less than 6ns. The echo mode is useful for the program to detect if the rs485 bus were in a. The usb4comim 4port rs422 485 usb to serial adapter combines serial communication signals, rs422 and rs485 port with usb technology to allow further expansion of existing serial devices. To illustrate their basic differences, a condensed description of each standard is presented in the following subsections.
Rs485 transceivers are available in both industrystandard packages and small, spacingsaving packages. This line driver receiver does not necessarily need to be an rs232 line driver receiver, but could e. The internal charge pump generates 10 v levels allowing rs232 output levels to be developed. The receiver also includes an enable signal equipment manufacturers could use to turn off the receiver. Rs 422, also known as tiaeia 422, is a technical standard originated by the electronic industries alliance that specifies electrical characteristics of a digital signaling circuit. Each device consists of a differential driver and differential receiver. Rs422485 to usb serial adapter cnet content solutions. Maxim offers a complete portfolio of interface devices. Low power rs 485rs 422 transceiver features low quiescent current. The part contains two rs 232 drivers, one rs 422 driver, one rs 232 receiver, and one receiver path which can be configured either as rs 232 or as rs 422. Pointtopoint applications may be thought of as using. Rs422, also known as tiaeia422, is a technical standard originated by the electronic industries alliance that specifies electrical characteristics of a digital signaling circuit.
Rs422 will support pointtopoint, and multidrop circuits, but not multipoint. Maxim offers over 160 rs 485 rs 422 transceivers for applications such as automotive, hvac, metering, and point of sale pos. Since both rs422 and rs485 are data transmission systems that use balanced differential signals, it is appropriate to discuss both systems in the same publication. If you require rs422, change the mode pin to the 422 position on. The adm4850adm4851 adm4852adm4853are halfduplex transceivers that share differential lines and have separate enable inputs for the driver and receiver. This application note attempts to cover enough technical details so that the system designer will have considered all the important aspects in his data system design. The main difference between rs422 and rs485 is that while rs422 is strictly for pointtopoint communications and the driver is always enabled, rs485 can be used for multidrop. Rs422 key parameters and topology rs422 is a unidirectional, multidrop network, allowing for the use of a single driver with an output signal that can be dropped at multiple up to 10 receiver nodes see figure1. Rs422 dual differential line driver and receiver pairs general description the ds892222a and ds8923a are dual differential line driver and receiver pairs. The adapter features a 9pin db9 male serial connector as well as dipswitch controls for easy port configuration, and requires minimal software. The rs422 interface is used for multi drop configuration and supports up to 10 devices at a time. The device contains one differential transceiver consisting of a line driver and receiver. The basics of rs 232422 485 multiport serial boards 10 the general relationship between the uart, ttl signal, transceiver, and rs232 signal is illustrated in the following figure. The ad7306 line driverreceiver is a 5 v monolithic product which provides an interface between ttl signal levels and dual standard eia rs232rs422 signal levels.
General description the maxm22510 and maxm22511 isolated rs485 rs422, fullduplex, transceiver modules provide 2500vrms 60s of galvanic isolation between the cableside rs485rs422 driverreceiver side and the uartside of the device. High end gps receiver with twisted air cable rs422 for boat, ship usable with plotter, radio, fishfinder, etc please be sure that you can connect rs422. General description the max481, max483, max485, max487max491, and max1487 are lowpower transceivers for rs485 and rs422 communication. Eiatia 422 defines a balanced differential interface. The max483, max487, max488, and max489 feature reduced slewrate drivers that minimize emi and. Max1487 are lowpower transceivers for rs485 and rs422 communication. The part contains two rs232 drivers, one rs422 driver, one rs232 receiver, and one receiver path which can be configured either as rs232.
General description the max3080max3089 highspeed transceivers for rs485rs422 communication contain one driver and one receiver. Ds96176 rs485rs422 differential bus transceiver rev. The rs422 differential data transmission is designed for 100kbps and for transmitting at distances of up to 4000 ft. The receiver outputs a logic high if all transmitters on a terminated bus are disabled. An rs422 driver may have this signal, but it is not. An integrated dcdc powers the cableside of the module. The default settings on the icusb422is are set at 2wire rs485 mode. Browse digikeys inventory of rs422, rs485 differential line driverrs422, rs485. Although rs422 is significantly different to rs232, it can often be used as a direct interface in many instances. The max487e max488e include a hotswap capability to eliminate false transitions on the bus during powerup or live insertion.
The rs485 specification meets the requirements for a truly multipoint communications network, and the standard specifies up to 32 drivers and 32 receivers on. Each driver output and receiver input is protected against electrostatic discharge up to 15 kv and has no latchup. Many include integrated features that reduce cost, design complexity, and board space by eliminating external components. The receiver is differential so that common mode noise picked up on the twisted pair of wires is cancelled. How to properly configure and wire rs422 and rs485. View more information about our rs485rs422 transceivers by category. Depending on the device receiver type, up to 32 12k impedance nodes or 11 rs422 receivers can be connected without a repeater. Because only one driver should be enabled at any time, the output of a disabled or powereddown driver is tristated to avoid overloading the bus. The texas instruments sn65hvd37 ic used in this example includes a 3state enable input to force the two driver outputs into a highimpedance state. Each driver output and receiver input is protected against 15kv electrostatic discharge esd shocks, without latchup.
1300 1035 731 444 523 469 945 1148 1501 1556 494 56 1356 613 880 869 858 89 544 1361 1576 108 1154 1321 17 1617 609 552 999 1476 1146 1206 1332 1328 451 1345 1440