Problems with trend view on SIEMENS MP277

Hi everyone
I have an issue with Multipnanel SIEMENS MP277. I've put one trend view to show one log from an usb memory card, it works 1-2 day, after that the trend view dosen't show the trend, only the clock in the center of its. The panel continues to log the dates as I can see in the file *csv from the usb card. Restarting the OS doesn't help.

Software WinCC Flexible 2005 SP1 HF7

My guess is that the panel tries to read from the USB stick, but when the file becomes big it also becomes impossible to read the file within the update time of the trend.
I have seen something similar on PCs, where the trend worked, but very sluggishly. A panel must be worse affected.

How often do you log to the USB stick ?

2 times per minute
No of data records per log - 115200
Max. size - 11251KB

do you think that 10 MB file is too big for panel ?

I dont know at what filesize the problems begin.
You would get 120 records per hour, and 5760 records after 2 days.
It does not sound as so much, but the panel has to read the file, and search through all the entries in order to create the trend based on the dates and times.
It also depends on how many tags you have setup to be logged.
I actually am surprised that you see the problem only after 2 days and not before. It shows us that the MP277 is actually quite potent.

I suggest you split the trend display into a regular trend (non-archived) and a historic trend (with archives).
There was a FAQ on Siemens Support on how to accomplish this.

Thank you JesperMP for answers. There are 6 tags for loging. Now the logging method is circular, how do you think the segmental circular log can help me?

Segmenting the logfile will help when writing to the file, and maybe also when reading from it. Even if segmented the panel still have to read all the archived data, even if it spanned over several files. I dont know how the panel can find out how to ignore files that only contain data that is not relevant to the current view.

You can try to change to segmented files, but no guarantee that it will fix it.
Try to change it to a combination of regular and logged trends as previously suggested.

Also, if it is just a regular USB flash stick, you shall not expect it to last more than maybe 100000 writes = a month or so. Maybe less, maybe more.

I forgot to say, regular trends work right. I sceptical see your opinion about write cycle. As I know total writes in a cell memory of regular USB flash stick is around 100000 cycle - like you said, but the pannel doesn't write only in the same cell memory. Don't you think?

I have had several regular USB sticks go bad on me.
I do not trust the rated write cycles for regular sticks. The manufacturers simply gamble on that 99% of the consumers never use the sticks for anything close to the rated cycles. They just specify some bogus value.
I trust the industrially rated flash cards.

Maybe this info helps me in the future, thanks. But now the panel archives without problems, as i said i can see in the *csv file, the problem is that the trend view doesn't show this.