Longest charting history

[labviewleroy]

I need to plot something over the course of a month+ and if I simply expand the chart history I crash after a little while. What would be the right way to graph something for this kind of period of time? 

[JÞB]

save the data to a file.  (use an event log to report Power outages, pc updates, network interuptions accidental reboots and maintenance activities you'll never keep a PC running for a month reliably)

Use a seperate app to copy then read the data for analisys.  A month of data in 1 chart?--- you'll burn the memory chip if there is a lot of data and won't see it all anyway. 

See if this KB article gives you any ideas

[RavensFan]

How rapidly are you collecting data?  How many data points are you collecting over a month?

There is a limit to the amount of data your PC can hold onto.  Do you really need to see a month's worth of data at a time?

If you are talking more than a few thousand data points displayed, you aren't going to be able to see it all because there is a limited amount of pixels available on screen.

If you are talking more data points than your PC can hold in memory, you are going to need to save the data to a file.  If you need to review past data, you will need to develop a method that only loads parts of the file at a time and displays them.  Or if you need to see the whole month at once, it loads the data from file in a decimated fashion such as loading every N data points and displayin them.

[labviewleroy]

i'm a bit confused about what you mean by "burn the memory chip". I take data about every second. I need to write to file, I agree, but I still want to display the chart the whole time. I dont want to have to recall a file in order to see a chart.

[Joseph_Loo]

If you want to keep a month's of history, the history length will have to be about 2,592,000 length. This implies that you will need to have a minimum of 16 Mbytes for each display element not counting the over head, (I am assuming it it is double). You will need that amount of continuous memory.

I believe they are talking about reliability of your system. If there are any failure of the machine, you will loose all the data. So what are your congiency plans for failure and keeping the data, e.g., what will you do if the machine is running and on the 29th day it crashes. What will you do with the missing data.

[Tori.M]

Hi labviewleroy,

If you can avoid displaying the whole month's data on one chart, it would be strongly recommended. However if you right-click on your waveform chart and select "chart history length" it will be possible for the number of points you require (at my calculation around 2.7million).

As a warning, this is risky and would not be advisable unless you have no other option! Ensure you are backing up the data to file and have contingency plans if the computer crashes etc.

All the best,

[asdfff]

   um anyone know how to delete posts? 

[labviewleroy]

 Someone brought up a valid point in terms of screen pixels. Assuming I have 1280 pixels accross my screen and I dont need to export the data and am content with just a chart, there really is no reason to have more than 1280 points. However, obviously if I just enter a history of 1280, after 1280 seconds I will begin to lose the information at the front.

There must be a way of doing this...keeping a chart going indefinately, but with only 1280 captured points at a time. 

[NIquist]

The chart will hold all your data (2.7 Million points is definitely pushing it though).  If you want to see only 1280 points (seconds) just scale the x axis to show that many.  You can even right-click a chart and check Visible Items > X Scrollbar so you can scroll the time axis.