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Archived Data - Different Trend & Exporting Data Time Stamps

Created by: hypergaph at: 11/1/2006 2:15 PM (5 Replies)

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11/1/2006 2:15 PM	Rate (0)
hypergaph Posts: 3 Rating: (0)	Hi everybody! I have a problem with the reading of archived values. First of all i have WinCC v.6 SP4 & Connectivity Pack v.6. I 'm trying to read the runtime values (the values that are in the <ArchiveManager> folder) via 2 ways and unfortunately there is a time difference between the two results. Firstly, I check the trends page and i see some values. Moreover, I use a VBA script to export the values in excel and I take the same values but with time stamp, 3 hours earlier. I check again & again the script but i believe that the problem isn't there. The strange in this situation is that both approaches (trends & exporting via vba) read the same archive (TagLoggingSlow) but the result is different. Somewhere in the forum, i read that trends read values from a different database. Is this correct? I'm saying this because i configure the trend so to read from the TagLoggingSlow archive. Is or not the same anyway? I know that the time of the SQL Server is in UTC time, (and the pc that wrotes these archives was set in local time), but if these two approaches read the same file (if so), how can the two results have the 3 hrs interval? Thank you all in advance! hypergaph
hypergaph Posts: 3 Rating: (0)
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11/1/2006 7:09 PM	Rate (0)
Ikkezelf Posts: 1084 Rating: (72)	is the time on your pc UTC +3 or not? if not what is it then? with regards, Ikkezelf
Ikkezelf Posts: 1084 Rating: (72)
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11/2/2006 9:47 AM	Rate (0)
hypergaph Posts: 3 Rating: (0)	Hi Ikkezelf & thanks for your time! The local time in my pc is UTC+2, and it is also ticked the selection "automatically adjust clock for daylight saving changes". regards. hypergaph
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11/2/2006 2:02 PM	Rate (1)
Salma Gold Member Joined: 9/27/2005 Last visit: 11/27/2007 Posts: 1398 Rating: (151)	Hi hypergaph OK this sounds fairly straightforward. Let me explain : WinCC stores all data in UTC time which is basically GMT0. In addition to this the clocks go forward (in most countries) during the summer. Here in the UK the clocks only went back again last Sunday. So your 3 hour difference appears to be the expected difference between your local time and UTC. Now whenever you query the database you will always get a UTC timestamp, irrespective of your local time, because this is the timestamp that is actually stored in the database. Hope this makes sense so far ! Now, WinCC must have some method to show data in local time format even though it is logging it in UTC format. To do this the Trend Control has been programmed to display either UTC or local time. This is something that the developers have conciously programmed in. If you wish to see local time in your exported data then you would need to program this into your VBS script. I hope this above answers your question and clears up any confusion. If I've just made it worse then let me know. [;)] Salma

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11/2/2006 3:37 PM	Rate (0)
hypergaph Posts: 3 Rating: (0)	Thanks Salma once again! This is the solution! To make a function to convert utc to local time. thanks both of you again! [8)] hypergaph
hypergaph Posts: 3 Rating: (0)
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11/2/2006 4:06 PM	Rate (0)
Salma Gold Member Joined: 9/27/2005 Last visit: 11/27/2007 Posts: 1398 Rating: (151)	Glad to help. You can find the function in this FAQ [:D]

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