Network Management

The primary task of network management is to control the transition of all LIN slaves in a LIN cluster from the normal communicating state (operational state) to the sleep state and vice versa. Power on causes a LIN slave to first transition to the initializing state. From there the LIN slave independently goes to the operational state after initialization (maximal 100 msec). As soon as the "Go to sleep" command has been detected, the LIN slave transitions to the sleep state. This command can only be sent by the LIN master. It is a so-called "master request frame" whose first data byte exhibits the value "0" (corresponds to NAD=0). The other data bytes are transmitted as 0xFF. The LIN slave also transitions to the sleep state when it has not detected any bus activity for at least four seconds (per LIN 2.1 it is not absolutely necessary for the transition to the sleep state to be accompanied by a low power state).

Each LIN slave has the ability to wake up the entire LIN network if necessary. To do this, the relevant LIN slave places a wake-up signal (dominant pulse) on the bus, which is at least 250 µsec long (maximum 5 msec). After detecting the wake-up signal (at the latest after 150 µsec), a LIN slave leaves the sleep state and switches over to the initializing state. After another 100 milliseconds the LIN slave transitions to the operational state.