RS422 wiring to RS485 Shield

Hi all,

I am currently working on a project using two arduinos to essentially extend an RS422 device over TCP/IP. The device uses the 4-wire TX+, TX-, RX+, RX- wiring but I can only find RS485 shields on the market, I have two of these shields for testing purposes at the moment and trying to work out if it will accept an RS422 input. I know the protocols are similar but also different in the way signal flows (full-duplex vs half-duplex) however the shield I am using seems to accept 4-wire.

The device requires bi-directional communication from either end so it probably further complicates what I’m trying to do using a 422 device with 485 shields.

The problem I’m facing is there is little to no documentation on these RS485 shields so I really have no idea if what I want to do is possible.

The RS485 Shield: http://linksprite.com/wiki/index.php5?title=RS485_Shield_V2.1_for_Arduino
Shield Schematic: https://s3.amazonaws.com/linksprite/Shields/RS485/RS485shield-v2.pdf

If this is not possible does anyone know any RS422 Shields that they can recommend? I am actually struggling to find one searching online.

Any help would be much appreciated. Thanks!!

The RS422 standard is a RS485 interface in permanent transmit (T+,T-) mode and a second RS485 interface in permanent receive mode (R+,R-)

For the transmit you need to force one shield into permanent transmit mode so that the A+ and B- of the RS485 becomes the T+ and T- of the RS422. any data that is then send on the TX line will be send to the remote unit.

For the receive you need to force the second shield into permanent receive mode so that the A+ and B- of the RS485 becomes the R+ and R- of the RS422. Any data that are send from the remote unit will appear on the RX line.