Method for the Automatic Time Synchronisation of Devices in Network-Based Systems

• US 20090083444A1
• Filed: 08/19/2008
• Published: 03/26/2009
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: VEGA Grieshaber KG (Grieshaber Verwaltungsgesellschaft mbH)
• Original Assignee: VEGA Grieshaber KG (Grieshaber Verwaltungsgesellschaft mbH)
• Inventors: Faist, Fridolin
• Granted Patent: US 8,838,776 B2
• Time in Patent Office: Days
• US Class Current: 709/248
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 2219/25478 Synchronize several controllers using syncline
• CPC Class Codes: G05B 2219/25479 Synchronize controllers using messages, add transmission time afterwards
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864

Abstract

A method is based on a communication- and data network for the automatic time synchronisation of field devices, namely fill-level measuring devices and pressure measuring devices as well as field-device control units. The method comprises the steps of: determining a current time value by the field device or by the field-device control unit, and providing a desired value in a central server. Furthermore, the method comprises the following steps: comparing the current time value with the desired value, and setting the current time value to the desired value when the desired value differs from the current time value by more than a predetermined threshold value.

Claims

1. A method based on a communication- and data network for automatic time synchronization of field devices, comprising:

determining a current time value by at least one of the field devices;

providing a desired value in a central server;

comparing the current time value with the desired value;

when the desired value differs from the current time value by more than a predetermined threshold value, setting the current time value to the desired value.

2. The method according to claim 1, wherein the field devices including at least two of fill-level measuring devices, pressure measuring devices and field-device control units.

3. The method according to claim 1, further comprising:

when the desired value differs from the current time value at most by the predetermined threshold value, taking over data from at least one of the field devices by the server into a database.

4. The method according to claim 1, further comprising:

transmitting the current time value by the field device to the server; and

determining a time difference between the current time value and the desired value.

5. The method according to claim 1, further comprising:

sending a reply by the server to the field device, the reply being indicative that the system time of the field device is acceptable if the desired value differs from the current time value at most by the predetermined threshold value;

transmitting all the data to be stored from the field device to the server; and

acknowledging receipt of the data by the server.

6. The method according to claim 1, further comprising:

transmitting a server time to the field device;

issuing a request for time synchronization of the field device with the server;

AND

storing the process of “

Time synchronization in the field device”

in a message buffer on the server.

7. The method according to claim 1, wherein the method is implemented in an acquisition system WEB-VV.

8. The method according to claim 1, further comprising:

requesting, by the server, the field device to carry out a comparison of clocks.

9. The method according to claim 1, further comprising:

only if the time in the server and the time in the field device are identical, permitting the server to take over the data.

10. The method according to claim 1, wherein at least one of the data groups of “

Time comparison data” and

“

Data to be stored”

is used in an XML-file format.

11. The method according to claim 1, wherein the field devices obtain the time information centrally using the server.

12. The method according to claim 1, wherein http communication is used between the server and the field devices.

13. The method according to claim 1, wherein the communication- and data network includes the Internet.

14. The method according to claim 1, wherein setting the current time value comprises time synchronization of the field device with correction of a real-time clock of the field device, and with correction of time stamps relating to data that is produced at that time in the field device.

15. The method according to claim 1, further comprising:

collecting various data records with associated time stamps in the field device; and

changing all the time stamps in the case of time synchronization.

16. The method according to claim 1, wherein the field device establishes contact with the server at predefined times using the communication- and data network.

17. A data- and communication-network-based measuring system for measuring one of a fill level and a pressure and for the automatic time synchronization, comprising:

a server;

at least one field device determining a current time value;

a communication connection between the server and the at least one field device for mutual data transmission;

wherein the server is operatable to provide a desired value in the server, the server setting the current time value to the desired value when the desired value differs from the current time value by more than a predetermined threshold value.

18. The measuring system according to claim 17, wherein the at least one field device includes a field-device control unit.

19. The measuring system according to claim 17, wherein the at least one field device generates and transmits time comparison data to the server, the server providing a threshold value relating to an allowed time difference and determining a time difference between the current time value and the desired value;

the server comparing the time difference with the threshold value and determining if the time difference is one of greater than and smaller than the threshold value, the server sending a reply to the at least one field device, the at least one field device transmitting a reply to the server, the reply being indicative if the time of the at least one field device is acceptable, the at least one field device carrying out time synchronization with a correction of time stamps of data produced at that moment being carried out in the at least one field device, the at least one field device transmitting to the server the data which is to be stored completely, the server taking over the data into a database, the server acknow ledging data receipt via the communication- and data network to the at least one field device, the server sending a server time to the at least one field device and requesting time synchronization of the at least one field device with the server and the server comprising a message buffer in which the server stores the process of “

Time synchronization in the field device”

.

20. A computer program for automatic time synchronization of field devices in a communication- and data network, wherein the computer program when executed on a processor causes the processor to carry out the following steps:

determining a current time value by at least one of the field devices;

providing a desired value in a central server;

comparing the current time value with the desired value;

setting the current time value to the desired value when the desired value differs from the current time value by more than a predetermined threshold value.

21. The computer program according to claim 20, wherein the field devices includes one of at least one fill-level measuring device, at least one pressure measuring device and at least one of field-device control unit.

22. A storage medium on which a computer program for automatic time synchronization of field devices in a communication- and data network is stored, wherein the computer program when executed on a processor causes said processor to carry out the following steps:

determining a current time value by at least one of the field devices;

providing a desired value in a central server;

comparing the current time value with the desired value;

setting the current time value to the desired value when the desired value differs from the current time value by more than a predetermined threshold value.

23. The storage medium according to claim 22, wherein the field devices includes one of at least one fill-level measuring device, at least one pressure measuring device and at least one of field-device control unit.

24. A microprocessor for the automatic time synchronization of field devices in a communication- and data network, and for carrying out the following steps:

determining a current time value by at least one of the field devices

providing a desired value in a central server;

comparing the current time value with the desired value;

setting the current time value to the desired value when the desired value differs from the current time value by more than a predetermined threshold value.

25. The microprocessor according to claim 24, wherein the field devices includes one of at least one fill-level measuring device, at least one pressure measuring device and at least one of field-device control unit.