HELP to acquire and create, beginner and scientist i am

[franzizi]

i did not change anything as i was waiting for your reply, but can you give me more solutions as i have some problems to create the file and plot in real time !
thanks

[franzizi]

Hi, i did make the modifications and now i'm using a timed loop. It is working perfectly and i now have the sampling frequency i want. The file result is "TextFile.txt".
My problem is now that my analog output is not working and so the analog input (directly linked) which must be recorded is not good. The analog ouput corresponds to the digital ouput triggering my vibrators. To ouput an analog i'm using a case structure linking one digital to a voltage value like 1 for a digital of 253.
But when i'm watching  at the graph or in the text file, the voltage do not correspond to the one i'm outputting.
Why ? Can you somebody help  me ?
is there other things wrong in my VI ?

thanks

[EmmaR]

Hi Francois,

Looking at your code, it seems you are outputting values on analog output 0. And then reading these in on analog input 0.

How are these two lines connected externally/physically?

Can you test your voltage outputs directly using an oscilloscope?- do you get the signal you want/ were expecting?

Thanks

Emma R

NIUK & Ireland

[franzizi]

Yes it is physically connected by BNC cables. I cheked the voltage and it is good so i dont know waht is going on ?
Do you have a simple way to plot and save the original digital ouput from the loop  ?
thanks 

[EmmaR]

Hi Francois,

I noticed that in your read loop you have set "dt" on your timing loop to 250. "dt" is the time between executions, which means currently that loop is only executing 4 times a second. Looking back at your original functionality specifications you stated that you required a sampling frequency of 250Hz. You therefore require a "dt" of 4.

Try changing this value accordingly and running your application. The difference in sampling rate may be the cause of the voltage output correspondance issue you were having. 

I have also tidied up your code for you. It is good coding practise to keep block diagrams wired with short straight wires so that it can be easily viewed in as small a space as possible. All inputs and outputs should be easily viewable and avoid placing items ontop of wires as it give the impression that the item is connected. All these rules makes your code more readable and hense easier to debugg.

Hope this helps

Emma R

NIUK & Ireland

[franzizi]

hi and thanks but can you send me a 7.1 version instead of the 8.0 version !
thanks

[EmmaR]

Hi Francois,

Sorry about that, here is the labview 7.1 version.

Emma R

NIUK & Ireland