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Entry type: FAQ, Entry ID: 26961516, Entry date: 04/19/2010

How do you do the summer/winter time switchover with WinCC flexible (update to version V1.1)?

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Use the latest version "Summer_Winter_Time_V1_1.zip".
With the previous versions, under certain circumstances there might be a time-of-day conversion error. If you are already using the previous version, then please replace FB80 including the instance DB in the STEP 7 project.

In the following example you can specify the exact times for the switchover between summer time and winter time via the operator panel.

The CPU clock serves as time master. This can be set via the HMI picture.
Based on the specified times, the CPU time is adjusted accordingly by +/- 1 hour for the switchover to summer time / winter time. The subsequent time synchronization with the operator panel is made via the "Date/time PLC" area pointer. This ensures that the time in the CPU and on the operator panel runs "synchronously" and you do not have to adjust the time manually on the operator panel.

No. Program description

STEP 7 project
Use the project template or copy the blocks FB80, DB80, SFC0 and the SFC1 into your STEP 7 project.
Then call FB80, DB80 in OB1. 


WinCC flexible project
Use the WinCC flexible project integrated in STEP 7 or copy the "DateTime" picture into your WinCC flexible configuration.
Furthermore, create the "Date/time PLC" area pointer in your project (DB80 DBW 22). Select 10 seconds for the acquisition cycle.

With the acquisition time you define the interval in which the HMI time is harmonized with the PLC.

3 Configuration notes on the "DateTime" picture

Bild 01

The "DateTime" picture includes various objects (IO fields).
These objects are assigned to various layers.
This makes it possible to show and hide individual fields in the Configuration View.

Next to point "1", for example, two objects are superimposed.
By showing/hiding the separate layers (e.g. 9 and 10) you can better edit/position the IO fields in area "1".

4 Operation of the configuration

Bild 02

Point 1:
Output of the current HMI time.

Point 2:
Output of the current PLC time.

Point 3:
Via the IO fields you can change the PLC time via the operator panel.
Use the "Set PLC Time" button to transfer the specified time to the PLC.

Point 4:
Graphics and text output indicating whether summer time or winter time is active.

Setting/presetting of summer/winter time
The central European states have Central European Summer Time, CEST, from the last Sunday of March to the last Sunday of October, at 2 a.m. central European time in each case.

Setting the summer time
Points 5/6:
Here you can specify the following, for example: "last", "Sunday". Alternatively you can specify any other date (e.g. "1st", "Monday" etc.).
If you wish to specify a fixed day, select ">Day<" via Point 6. You can then specify the weekday under Point 5.

Point 7:
Specification of the month.

Point 8:
Specification of the time when summer time begins.

Setting the winter time
Point 9:
In this area you specify when winter time is to begin.
The procedure is the same as for the summer time.

Important notes

  • You can only use the attached example in connection with the "Audit Function" (regulated project). There is no time change in the "DeltaToUTC" column in the Audit Trail file.
  • You must set the controller as time master for setting the time. It you operating the controller as time slave, the time master has to do the summer time / winter time change.
  • You can also use the FC60 block (for CPUs without time-of-day status) or FB61 block (for CPUs with time-of-day status) from the "Standard Library" (under "Miscellaneous Blocks" > "Blocks") to do the summer time / winter time change in the CPU without operator action. Information on this is available in the Help for the block concerned.
  • You may not use this sample application and a WinCC application simultaneously. A time change via the PLC is not permitted in WinCC. WinCC always uses UTC time.

The attached download contains the archived STEP 7 and WinCC flexible project with the functions described above.

Attachment 1: Summer_Winter_Time_V1_1.zip ( 3584 KB )

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