Box-2-Box: Relay control over LAN
Image:

English
Perex:
Two I/O Controller units can be connected against each other over a LAN. Digital inputs are then connected over the network to relay outputs. The delay is approximately 200ms. With a remote LAN relay, it is possible to switch any device on or off.
Features:
Each unit can connect to the remote unit
When the power fails and is restored, the unit automatically retrieves input states from the remote unit
Uses a Telnet-like protocol with optional security enhancements