Dear Reader

I would like to discuss the following problem I have been having.

I've been working on a project that plots 2-dimensional points on a trend control object in a runtime application. The way this works is by writing to a CSV file via a VB script and linking the CSV file to a trend control object.

My HMI has 3 pages, each with 2 Trend Control objects (Left Results and Right Results), totalling 6 CSV files acting as data sources.

I recently switched to using Windows 11 and noticed something odd about my result screens and ultimately about the CSV files.

During the process of writing to a CSV file (this includes: closing all logs, writing to the CSV file and opening all logs) the other CSV files are overwritten (or have their content deleted?). I notice that the data collected in an overwritten CSV file is stored in a .csv.BAK file, but when the next CSV is handled, this .BAK would also end up with the (now empty) contents of the previous .CSV.

After a long, ineffective debugging process, I decided to open the runtime application on Windows 10, where I immediately noticed that the data logging was working as intended again.

Is it possible that the Windows version is the cause of my problem? Maybe there is a different computer setting? Does anyone have any knowledge of this?

Either way, maybe this post can warn people struggling with WinCC data logging on Windows 11.

The project is in TIA V17.0 / RT Advanced. Unfortunately I'm not allowed to share the project, but I'd be happy to share the VBS code if anyone is interested (it is based on an example project for plotting graphs from 2 array's)

I have found very limited information about this BAK file and the conclusion is that there must be a bug in my routine that creates these files. I've noticed that on W10 these BAK files also appear after a while, but never at the expense of the functional behaviour of the program (i.e. I never lose the previously plotted graphs on the trend control objects).

On my windows 11 pc selecting option 'Append to existing" doesn't seem to work. When runtime starts and all logs are opened, the CSV files suddenly becomes empty en the lost data is found in .BAK

The logging destination is the same on both PCs (W11 and W10): "C:\Logs\". So I don't think the W11 user folders synchronisation will come into play, although it's a good remark.

Since using Windows 10 for the machine's application is not an issue, I'll probably continue to do so without creating a ticket.

Hi all

Thanks for the replies.

I have indeed used this example to base my VBS code on.

The good practice that this sample project demonstrates is that you should wait until the log is properly closed before you start writing. This is to prevent a .bak being generated.

I made sure to link the system events to set the AllLogsClosed and AllLogsOpened bits so that the VBS has a handshake with the open/close process of the CSV files. It's possible I didn't do this correctly, I'll check.

Still strange that I lose my measurement data on one PC (Win11) and keep it on the other (Win10).