Wincc data logging

stevennoppe

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Join Date
Apr 2007
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Belgium
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12
I can't seem to find much information on the trend view object of WinCC from Siemens.

I know that I can write to an Access database file, but I have a few questions about it :

1) Does Wincc write the data unlimited to the file? Will I for example be able to look at data from say a year ago? (I'm not sure because "the number of data records per log" is maximum 500000.)

2) Can I search for a specific date in the history trend view with the help of VB scripting? If so, how do I do this?

thanx in advance for any help
 
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1, the trend view object is simply to view the data, not to store it.
2, It stores its data in SQL format not Access, although it is MS SQL.
3, I am still getting my head around it, but the inbuilt taglogging function is limited to the total number of records. It also has limitations of the log time and size of each file. Generally you setup a series of files (to a maximum number), and when either the log time or the file size reaches its limit, the file is closed and a new file is created. If you have reached your maximum number of files, the last file is deleted.
4, Accessing your data can be done through SQL functions, exactly how to do this is something I don't yet know. Siemens will also sell you a program that will export this data to other SQL databases or to Excel or Access databases.
 
Here is a few screen shots in WinCC Flex. After you setup the log you can display it with a trend by setting the trend data to log and select the log. You should also be able to find more info from the help files. I do all my logging to a file. To log to a database you will need to setup the datasource. I assume you would setup Access database in ODBC on the computer that is logging the information. Then you would select the datasource in Flex for the log. I know you can get to the data in Access with a script but I have never done it. You should be able to give standard SQL commands in a script for the search.

data_log1.JPG

data_log2.JPG

data_log3.JPG
 
Thx for the reply, but I already have done this and my question was in fact, how many of my data will be kept in the log file?


1) Does Wincc write the data unlimited to the file? Will I for example be able to look at data from say a year ago? (I'm not sure because "the number of data records per log" is maximum 500000.)
 
I think it depends on how often you are logging and how large a file you want. Do you have any idea how much and how often?

I see what you mean 50000 is the most data records it will log to a database. I don't know how they came up with this number. I would think that Access could do a lot more than that. You can setup an event when the log gets full. You may be able to use this to move the data from one table to another. This would take care of the log but I don't know how you would display the data you moved out of the log. You may have some option just depends on how much and how often.

Ok if you use a segmented circle log you can setup mutilple logs up to 500. So you can log 500x50000 records. Thats a lot of data.
 
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The way I see it : every second I log a tag : 500000 / 3600 = 138 minutes = only about 2 hours :(
and besides : I want to log 3 different temperatures in 1 log file so this means : 138 /3 = 46 minutes?!?

Or do I have it all wrong?
 
Each log or record in the database will have all 3 temps.

So 1 log every second, 60 logs a minute, 50000/60 = 833 minutes per log file.

If you use a segmented circle log then you get up to 500 log files so 833 minutes * 500 files = 416500 minutes or 6941.6 hours /24 = 289.2 days.

Thats how I see it.

cir_log.JPG
 
I am an expert in WinCC and WinCC Flex MIS.
The built in data logging options in WinCC flex do no good when it comes to long term data logging.
What we do is log the data using custom scripts to SQL express edition which is free of cost (limited upto few gigabytes per segment)
 

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