dynamic history size of xy chart buffer

[looser]

Hi all..
My question is that when I wanna plot dynamic xy graph I should use xy chart. Till here everything is ok. But the option""history size"of xy chart buffer forces me to determine how many points of history data will be displayed. But  what i want is that not fixing it, i wanna see all measurement points till i stop the measurement. thats why i connected to history size option to loop number indicater so that after each measurement i would be able to see all the previos datas till i stop the loop. But it doesnt work!! Does my approach is wrong?

[Sima]

Is there anyway you can estimate how long your measurements will last? It's usually not a good idea to store a lot of data in a graph because it is memory intensive, and the redrawing is also CPU intensive. Typically, you graph just a window of your data for viewing, and log all your data to file for post-processing.

[altenbach]

Sima is right.

You cannot have an unlimited history size on a computer with limited memory and resources (Yes, even gigabytes is not infinite). If course you can make your own history buffer by growing the x and y data in shift registers, but at one point during run the system will bog down due to constant memory reallocation operations. Also you cannot possible display more data that fits on a typical screen.

Typically there is some knowledge on an upper boundary, so you can preallocate suitable buffers. If the history is bigger than fits in memory, stream to disk and add some mechansims to browse through history data by reading selected portions back.

[looser]

Actually, it s want i want to do. I wanna just display the measuremnt on a graph, i ll store the the result as a spreatsheet anyway. My measurment is going to be a hystresis loop, each loop consists of 300 measurments points, and i ll need to aveage several loops lets say maximum 20 loops causing 6000 measuremnt points. The question is what would happen if my measuremnt length is not as long as set history size? i read the description of buffer size vi but it s quite confusing.
another question is that measured datas by xy charter is stored in the memory for how long? each time when i stiop measuring, is it deleted?
what would you reccomend me to use in order to display my measurement dynamically, and storing the data at the and the experiment as a spreadsheet? I dunno if i m the only one who finds those graphs quite comlicated due to the abundance of them and similarity.