If a Master Brick is used on its own or in a stack communication is done by its USB interface. Master Extensions extends the communication interface of Master Bricks. There are cable based (RS485, Ethernet) and wireless Master Extensions (WIFI) available. Instead over USB Bricks and Bricklets can be controlled over Wi-Fi or Ethernet. RS485 can be used to interconnect Bricks and Bricklets over larger distances.
From a programming perspective the different interfaces are transparent. A stack with Master Extension behaves as if every Brick in the stack would be directly connected to the PC over an USB connection.
This means: You can develop an application with all modules independently connected to the PC over USB. Later you can stack these modules together to stacks, add Master Bricks and cable based or wireless Extensions and you can run the previously written code without any changes.
|Ethernet||Cable based Ethernet connection between stack and PC|
|RS485||Cable based RS485 connection between stacks|
|WIFI||Wireless Wi-Fi connection between stack and PC|
|WIFI 2.0||Wireless Wi-Fi connection between stack and PC|