Master and slave ECUs are connected to the LIN bus lines. The master ECU is the ETACS*-ECU, and the slave ECUs are the column switch (column-ECU), the sunroof-ECU <vehicles with sunroof> and the lighting control sensor <vehicles with lighting control sensor>. The master ECU requests these slave ECUs to communicate each other via communication lines.
note *: ETACS (Electronic Time and Alarm Control System)