MODBus shield

This is the second PCB I've developed. It is an arduino-shield for my home automation project. It is also devoped using CADSoft EAGLE and was produced by PCB-Devboards in Germany.


This shield has the following features:

  • RS485 interface driver wsith optional active termination
  • 1-Wire interface with overvolt-protection
  • Two open-collector drivers
  • Two S0 inputs
  • I2C interface with internal pull-ups
  • All external connections accesible on WAGO clamps


Here the shields is place on top of an Arduino Ethernet mounted on a PCB inside a DIN rail housing.

 IMG 3400s

The jumper in the right upper corner can be used to disconnect the RS485 receiver output from the Arduino RX pin, so the sketch can be programmed using the Arduino Ethernet serial connector (the pins can be seen under the right edge of the board).

The clamps on the left side of the boards are used for external connections. They are from the German WAGO company and feature a 2.54mm pin spacing - but they are not cheap - you have to pay 3€50 for the 12-pin version at the Reichelt online store.

The shield is mounted via pin headers on top of the Arduino Ethernet board. To get enough headroom for the RJ45 connector on the Arduino Ethernet board, I have to use the extra-long headers. I found them for a reasonable price at a small online-store in Spain - FADISHOP. I'm very satisfied with this shop, you can pay via PAYPAL and the goods are delivered within 5 days from Spain to Germany!