We use a small and cheap single-board computer as network-based IO-device. It’s called ODROID C1 (C1+/ C2) manufactured by Hardkernel. Basically it’s a faster cousin of the raspberry pi with gigabit LAN but still affordable. It runs Linux and in our configuration it autostarts a basic ‘server’ that listens to network-commands that control the GPIO-pins. It also listenes to IN pins and sends the pin status over LAN. In our hands this turned out to be a very convenient, reliable and fast (on-off-on-off within 1ms) system. The system can be configured through a text file on ODROID.
Many thanks to Henrik Wild of Panogate for his support with this project.