The XPData Library v4.x is the branch of previous "XPData-3x" and early "XPlaneData" project. You can use this library to build your Input/Output control interface for X-plane easy and quick.
No other software and plugin is needed! All data is transmitted directly to X-Plane using its built-in UDP protocol.
You can use as many Arduino boards with XPData input library as you need to. All boards should have an Ethernet shield (or module) connected to your LAN.
Connect Arduino with Ethernet Shield to you LAN, upload sample code to Arduino (see menu XPDataInput--Examples), enter appropriate IP-addresses in the code, start X-Plane.Then you can start to configure your input system using the library functions for various digital and analog input types and receive X-Plane dara to use them for output devices.