The LIN Bus Module allows your microcontroller to communicate over the LIN (Local Interconnect Network) protocol. This protocol is used widely in industrial and car based systems, and allows two way communication via a single data line, together with a GND line and a 12V power line. The LIN protocol allows for one master and fifteen slave devices.
On one side of the module are the connections needed to interface with your microcontroller or development board, and on the other two sets of screw terminals, one for data to come in and another for data to pass through onto another module on the bus. There is also a jumper on the module that allows you to select whether this module is the master or the slave. When the header is in place, the 4K7 pull-up resister is active, meaning the module is now acting as a ‘master’ on the bus.