> One chart or graph (depending on which I should use) of the 10 will
> therefore receive 2 * 13bits of data/second
> Multiply up for 6 hours = 26*60*60*6 = 496'000 bits in 43200 samples
> or char points.
> I don't know which to use, chart or graph, and I don't know what you
> mean by "decimate it for the display".
> 

So after six hours, you will have about 40K samples?  That is nothing 
for the graphs to churn through, they can start to sweat when you get 
into the 5M range, but you shouldn't have a problem with your plot size. 
  What I meant by decimate was to resample a plot to have a smaller 
amount of data.  There are numerous techniques for doing this, the 
simplest being to take every Nth point.  Doing this on the diagram 
really isn't necessary until you get way more points.

I haven't seen your panels, so I'm not the best person to tell you which 
to use, but charts have their own statically configured circular buffer 
built in.  You set them to retain N points, and then you set the scales 
to show a time window on your data, up to 100% of it.  Graphs have no 
internal storage, they plot what you give them.  They both support you 
setting the scales to whatever window you like, or support autoscaling, 
which obviously adds a small amount of computational time.  You might 
want to make a prototype UI with random or otherwise simulated data, and 
play with then to determine which works better.  In the simulation, you 
can even speed up time, turning your six hour acquisition into a six 
minute one and speed up your development time.

> Additional information:
> I need to calculate (and graph?) the capacity of a battery-pack. I
> have the voltage and current that goes in or out of the battery
> (sampled 2/sec). If I multiply every volt-sample with every current
> sample and plot/graph them and calculate the integral of that curve, I
> can use that to see the remaining capacity of the battery. Can I apply
> the "time domain Math" to a "chart" vi?
> 

Almost.  You don't really apply things to a chart, but to the data that 
you either retrieve from the chart, or the data that you gave to the 
graph.  In otherwords, the display objects don't do analysis, but you do 
analysis on the data you gave to them and display it wherever you like, 
possibly on the same graph.

Greg McKaskle


Reply via email to