Patent ID: 7343437

Claim:
A synchronization method for time synchronizing at least two slave units which are controlled by a master unit, and two signal lines each going through each slave unit exactly once in opposite order, the signal lines being configured so that a signal sent by the master unit passes through all of the slave units on at least one of the signal lines and returns to the master unit, the method comprising: determining a signal throughput time required by a signal transmitted by the master unit until it returns; reporting the signal throughput time to all of the slave units; transmitting at least one control signal by the master unit to all of the slave units as a reference signal so that each slave unit receives the at least one control signal via both signal lines, wherein each of the slave units performs the following: starting a first time count upon reception of the at least one control signal via the first signal line, starting a second time count upon reception of the at least one control signal via the second signal line, adding the two time counter contents to provide a sum, comparing the sum of the time counter contents with the reported signal throughput time; reading out the time counter contents when the time counter contents which have been added up correspond to a reported signal throughput time; and determining a time correction parameter for each of the slave units with respect to each signal line based on at least one read-out counter content, the slave units performing the time synchronization taking into account the time correction parameters.