Charging of capacitor, timing and flat-seque​nce struture

Question

Hello
First I'll give you some information about my project:
I'm quite new to Labview, but I have programmed alot with C++/C/Assembly. The attached program is a small part of a bigger system, but I made a quick version of it, just to get the hang of it. A capacitor (image) will be charged up to 3,3V. I'll do two measurement at 2,5 V and 3,3 V, at about 3 tau and 5 tau of the charging. There are some timelimits and it's here I got some problems.
Sequence:
From start the signal have to be 0V for atleast 300 ms.
The the capacitor have to reach atleast 2,5V within 430 ms from start.
Then the capacitor have to reach 3,3 V within a maximum of 510 ms from start.
My attached program is built in a flat-sequence structure (maybe statemachine is better?). If I change the "Wait 300 ms" to "Wait 80" ms, the first time-check will pass. If I use 300 ms, the first time-check is about 600 ms and the last 950 ms (It should have been 430 ms  - 300 ms = 130 ms, and 510 ms).
I'm not asking you to make anything for me, but maybe give me a hint where to look. Would a statemachine do better than the flat-sequence? Am I on the right track regarding time-checking, or is the Tick Count useless in this case?
Is the code within the Ruby Goldberg category?
Extra info: I got LV 2009 and 2010, but only the basic versions. The DAQ in my program can be replaced with a signalgenerator of 2,5 V and 3,3 V just for testing.
I think the program does its job, but my timing is not on track.
Thanks for any help.
Regards,
Even
Regards,
Even
Certified LabVIEW Associate Developer
Automated Test Developer
Topro AS
Norway
Solved!
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Attachments:
Charging of capacitor.vi ‏128 KB

Answer 1

Hi again guys=)
Well yesterday I used the Daq Assist. I find it quite useful, but since I've used it alot now, I think it would be better to use something like tbob put together.The thing I had some problems with was:
I used the Daq Assist to get 1000 samples in 1000 ms. 1 sample per ms. Then I put that into an array using build array. After that I made a for-loop with 100 interrations, in other words I wanted 100 samples of the total of 1000, but on my graph I could not see anything.
As soon I has connected A, the counter C would not count from 100 til 200, but only switching between 100 and 101. If I removed the connection A, the counter worked fine. The conversion of dynamic data automatically popped up when I made the connection. I also thought the index array worked like this:
I can say which number in the array I want to read the data from.
The problem is that it returns a value only at index 0 or 1.
Then I finished at work. Today I'll study the context help abit more and try to find some other examples on how to extract data from an array.
For now I'll study your snippet, tbob, and learn howto set-up Daq without the Daq Assist. I also see that my attempt to extract data from an array also was wrong so I'll try again in an other way.
Thanks for the help guys
Regards,
Even
Certified LabVIEW Associate Developer
Automated Test Developer
Topro AS
Norway