Synchronization method and control system for the time synchronization of slave units and a synchronizable slave unit

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.

A control system for time synchronizing at least two slave units, comprising:

• a master unit for controlling the at least two slave units and having two signal lines each going through each slave unit exactly once in an opposite order, the signal lines being configured so that a signal transmitted 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 master unit including:
• a time measuring device for determining the signal throughput time needed by a signal transmitted by the master unit until it returns, and
• a communication device for reporting the signal throughput time to all of the slave units, the communication device transmitting at least one control signal from the master unit to all of the slave units as a reference signal, so that each of the slave units receives the at least one control signal via both signal lines;
• wherein each of the slave units includes:
• a first time counter to count a first time interval since receiving the at least one control signal via the first signal line,
• a second time counter to count a second time interval since receiving the at least one control signal via the second signal line, and
• a control unit having an adder for adding the two time counter contents and providing a sum thereof, a comparator for comparing the sum of the time counter contents with a reported signal throughput time, and a device for reading out the time counter contents when the sum of the time counter contents corresponds to the reported signal throughput time;
• and
• wherein a time correction parameter is determined for each of the slave units with respect to each of the signal lines based on at least one read-out time counter content, the slave units performing the time synchronization taking into account the time correction parameters.

A synchronizable slave unit of a control system, the slave unit being controlled by a master unit, and two signal lines going through the slave unit, the slave unit receiving a signal throughput time reported by the master unit and also receiving a reference signal via both signal lines, the reference signal being transmitted by the master unit to the slave unit in the form of at least one control signal, comprising:

• a first time counter to count a first time interval since receiving the reference signal via the first signal line;
• a second time counter to count a second time interval since receiving the reference signal via the second signal line;
• and
• a control unit having an adder to add the two time counter contents and to provide a sum thereof, a comparator to compare the sum of the time counter contents with the reported signal throughput time and having a device for reading out the time counter contents when the sum of the time counter contents corresponds to the reported signal throughput time, and a time correction parameter being determined with respect to each signal line for the slave unit based on at least one read-out time counter content;
• Wherein the slave unit performs the time synchronization taking into account the time correction parameters.

A synchronization method for time synchronizing at least two slave units which are controlled by a master unit, in which two signal lines go through each of the slave units exactly once in opposite order, the signal lines being configured so that a signal transmitted by the master unit on at least one of the signal lines passes through all of the slave units and returns to the master unit, the synchronization 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 from the master unit to all of the slave units as a reference signal so that each of the slave units receives the at least one control signal via both of the signal lines, each of the slave units performing the following:
• starting a first time count upon receiving the at least one control signal via the first signal line,
• starting a second time count upon receiving the at least one control signal via the second signal line,
• adding the two time counter contents to provide a sum thereof,
• comparing the sum of the time counter contents with the reported signal throughput time, and
• ascertaining a point in time when the sum of the time counter contents corresponds to a reported signal throughput time;
• and
• synchronizing the slave units based on the ascertained point in time.