I cannot answer for all controller implementations. But the Vera-plugin asks for version when it start up. https://github.com/mysensors/Vera/blob/master/L_Arduino.lua#L650 This is how we do it in the dev-branch https://github.com/mysensors/Arduino/blob/development/libraries/MySensors/examples/EthernetGateway/EthernetGateway.ino#L177