I'm working currently on a professional RS422/RS485 shield for the Arduino UNO (and compatible boards) and other SBC with Arduino style headers (like STM Nucleo) . I wasn't satisfied with the shields on the market. They are very simple and have some disadvantages. My shield comes with the following features:

 

  - RS485 mode (half duplex)

  - RS422 mode (full duplex)

  - galvanic isolation between Arduino and connected RS485 bus

  - free choice of TX-pin between pins 0-5

  - free choice of RX-pin between pins 0-5

  - enhanced ESD protection

  - adjustable automatic transceiver switching for RS485 mode

  - adjustable control of transceiver/receiver via pin 6 or 7

  - adjustable Pull-Up, Pull-Down und terminating resistors

  - indicator LEDs for RX and TX

  - removable block terminal for bus connection

  - many options adjustable via DIP switches

  - stackable headers

  - can be configured for 3.3V and 5V logic

 

 

Arduino RS422 RS485 shield with isolated interface

Arduino style RS422/RS485 shield and STM Nucleo board