Brainboxes ES-020 Manual descarregar pdf (Página 20)

ES Range Product Manual

Version 2.8

Page 20 of 57

RS422/485 Settings

The factory default setting for the ES devices is RS422 full duplex.

Background Information:

DTR/DSR Handshaking is not available on 422/485 ports. Check your product datasheet to see if

RTS/CTS is supported.

RS422 Full Duplex Mode

This mode is generally used between one transmitter / receiver to only one other transmitter /

receiver, but it is possible for each output to drive up to 10 receivers.

Generally, in RS422 systems, all 8 signal lines from the 9 pin D connector or terminal block participate

in the data transfer sequence. Thus 4 twisted pair cables are used. One twisted pair carries the TXD

data outwards, one pair brings the RXD data inward, another pair carries the RTS handshaking signal

outwards, and the fourth pair brings the CTS handshaking signal inwards. There is no need to carry

the ground from one device to another.

This mode is generally used between one transmitter / receiver to only one other transmitter /

receiver, but it is possible for each output to drive up to 10 receivers.

NB: Please check the product datasheet for your device to see what hardware handshaking is

available.

RS485

The RS485 standard is similar to the RS422 standard upon which it is based. The main difference is

that up to 32 transmitter / receiver pairs may be present on the line at one time.

Generally not all the lines available on the 9 pin D connector or terminal block are used for RS485

systems. The RTS+/- and CTS+/- lines, though driven by the device, are usually not connected. In

two wire Half-Duplex configuration, the TXD+ line is connected to RXD+, whilst the TXD- line is

connected to RXD-. Only one pair of twisted wire cable is used in RS485 Half Duplex communication.

These are the two main wiring schemes:

RS485 One Talker Many Listeners (Half Duplex)

RS485 Many Talkers Many Listeners (Half Duplex)

Please see Section 18 for the pin outs of RS422 and RS485 for your ES Device.

RS485 Full Duplex Mode (ES-313, ES-320, ES-346 & ES-842)

This mode is generally used between one transmitter and many receivers. It uses 2 twisted pair

cables, one carries the TXD data outwards and one brings the RXD data inward.

H+

H-

B+

3V3

B-

GND

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Brainboxes ES-020 Manual Página 20