A tips is buying the Arduino Ethernet and the Skaarhoj GPIO/Tally extension, then you can code your own functionality. It works really good actually
http://skaarhoj.com/wiki/index.php/SKAARHOJ_2x8_GPIO_board
I am currently using the code and working on a wireless tally system for the ATEM, found here:
https://github.com/coral/Wireless-ATEM-Tally
Even if my system doesn't require the breakout board it uses the code.