This Software aims to control an 8channel relay with a Midi keyboard or any other suitable midi device. It can be controlled with MAX by cycling74 or processing. Simply download MAX or processing and open the respective file in this repository. Please be aware that this was testet in MacOS Environment only.
If you want to set up your own communication between a software and the arduino you can easily do this. The communication to the Arduino is encoded in one byte, each bit representing one of the relay's channels.