Varying Chart History length

[chris.mckenzie]

I am working on a data acquisition, analysis and display program, which basically take the form of two parallel loops joined by a queue. In this program I wish to allow the user to set the sample rate (done by varying the while loop wait) and to specify how long a time period is displayed on the chart (which concerns the chart history length). For example if 50 samples per second and 20 seconds are selected, the chart history length should be 1000.

Unfortunately chart history length isn't included in the chart property node to change programmatically, from the ni support I found a method which constrains the history array to a certain length.

http://digital.ni.com/public.nsf/allkb/E9784F413A2269E086256F3A0064C8BB

I had a go at changing it to be more suited to my problem, however I couldn't quite get it to work (time axis doesn't progress). Is this the only method? What have I done wrong? Will this be a performance issue when used on a number charts?

If anyone could help with my attempt it would be appreciated.

[tst]

Chris, posting the same question multiple times is terribly anti social. The people in this forum often invest considerable effort in answering the questions, and by posting twice, you could be causing different users to try to answer your different posts, instead of the discussion being limited to one thread. Most people here are not from NI, and do this completely voluntarily. It may take time (even a few days to weeks) before someone who has the answer to your question notices it or has time to answer (although most questions get answered within a few hours. For example, in your other thread you got one answer after 15 mins, another after 90 mins and another after 25 mins).
You should be patient. You will get your answers in the other thread you posted.

Message Edited by tst on 03-17-2005 12:01 AM

[chris.mckenzie]

Sorry to have caused any offense, this is only my second post. I wasn't sure on the protocol, I thought once my post got to the 3...5 page, it would be forgotten.

I will remember this for next time.

[tst]

No one was offended. I just pointed out that there is no reason to make people do redundant work. You are correct in the fact that a thread that gets to the back pages may be ignored, but it's better to post another message to that thread to bring it to the top than to post a new one. You should also wait before you do that, unless you're really pressed for time.