Method for synchronizing a local time base on a central time base and device for implementing said method with preferred applications

1. A method for synchronization of at least one local timebase in a local technical system to a central timebase in a central technical system, with time messages being transmitted from the central timebase to the local timebase, comprising:

detecting the transmission time of a time message by the central timebase and entering the detected transmission time as a data value in a subsequent time message;

detecting the reception time of a time message, and reproducing the value of the transmission time contained in a subsequent time message by the local timebase;

determining time discrepancies between the local timebase and the central timebase by the local timebase, from a difference between associated transmission and reception times of time messages; and

evaluating values of the time discrepancies by the local timebase, for synchronization of the local timebase, and determining correction values for the local timebase therefrom.

2. The method as claimed in claim 1 , further comprising:

determining time discrepancies by the local timebase in conjunction with a group of time messages transmitted during an observation period; and

forming a correction value by the local timebase from a minimum value of the time discrepancies determined in an observation period, and using the correction value for synchronization.

3. The method as claimed in claim 2 , wherein the correction value corresponds to an initial value of a control algorithm, to which a value zero is supplied as a set value, and to which the minimum value of the time discrepancies determined during an observation period is supplied as an actual value when forming the correction value.

4. The method as claimed in claim 3 , wherein the correction value is applied in a distributed manner to a local timebase during a subsequent observation period.

5. The method as claimed in claim 3 , wherein the observation period includes a predetermined number of transmitted time messages, further comprising the steps of:

forming a partial correction value by division of the correction value by the predetermined number of transmitted time messages, and

applying the partial correction value to the local timebase for synchronization for each transmission of a time message.

6. The method as claimed in claim 4 , wherein the observation period includes a predetermined number of transmitted time messages, further comprising the steps of:

forming a partial correction value by division of the correction value by the predetermined number of transmitted time messages, and

applying the partial correction value to the local timebase for synchronization for each transmission of a time message.

7. The method as claimed in claim 2 , wherein the correction value is applied in a distributed manner to a local timebase during a subsequent observation period.

8. The method as claimed in claim 7 , wherein the observation period includes a predetermined number of transmitted time messages, further comprising the steps of:

forming a partial correction value by division of the correction value by the predetermined number of transmitted time messages, and applying the partial correction value to the local timebase for synchronization for each transmission of a time message.

9. The method as claimed in claim 2 , wherein the observation period includes a predetermined number of transmitted time messages, further comprising the steps of:

forming a partial correction value by division of the correction value by the predetermined number of transmitted time messages, and

applying the partial correction value to the local timebase for synchronization for each transmission of a time message.

10. An apparatus comprising:

a central data processing device for forming a central timebase;

central communication means for supplying time messages to a data bus;

central synchronization means for detecting the transmission time of a supplied time message and for entering it in a subsequent time message before being supplied as a data value, and including at least one local data processing device, the at least one local data processing device including,

local means for forming a local timebase,

local communication means for receiving time messages from the data bus, and

local synchronization means for detecting the reception times of the received time messages, for reading the transmission times contained in the received time messages, for determining time discrepancies between the local and the central timebase from associated transmission and reception times, and for determining a correction value for the local means from the determined time discrepancies in order to produce the local timebase.

11. The apparatus as claimed in claim 10 , wherein

the local means each include a timer module in order to form a local timebase, the timer module being decremented cyclically by a clock and, after complete decrementation of a start value, emitting a timing signal for the local timebase;

wherein local synchronization means applies the correction value to the respective timer module as the start value.

12. The apparatus as claimed in claim 11 , wherein the local synchronization means,

forms the correction value from the time messages received in an observation period.

splits the correction value into partial correction values, and

applies these partial correction values to the timer module in a subsequent observation period.

13. The apparatus of claim 12 , wherein the partial correction values are applied in time with the reception of time messages.

14. The apparatus as claimed in claim 10 , wherein the local synchronization means,

forms the correction value from the time messages received in an observation period,

splits the correction value into partial correction values, and

applies these partial correction values to the timer module in a subsequent observation period.

15. The apparatus of claim 14 , wherein the partial correction values are applied in time with the reception of time messages.

16. An apparatus, for use in a production facility, comprising the apparatus of claim 10 , wherein the production facility includes a local data processing device which actuates local technical equipment in time with the respective local timebase.

17. The apparatus for use in a production facility as set forth in claim 16 , wherein the production facility includes electrical drives as the technical equipment.

18. The apparatus of claim 17 , wherein the local data processing device interchanges control variables, with the associated local technical equipment, in synchronism with the respective local timebase.

19. The apparatus of claim 16 wherein the local data processing device interchanges control variables with the associated local technical equipment, in synchronism with the respective local timebase.