Im creating a simple PID controller, however i cannot graph the output

[Pritz1]

I have created a simple PID controller but the output cannot be drawn on a graph as i have connected two different types. I have my file attached, Is any one able to assist me

 

[natasftw]

I'm using 2014 so I can't open your VI.  It looks like it's a simple data type mismatch.  Change the graph to be a double datatype.

Are you using an array of data from the PID? I thought it was a single scalar value.  In that case, you'd want a chart instead to keep updating your history as you go.  The graph won't maintain a history for you.

[Pritz1]

Well i am acquiring data from a data aquisition card, i will give that a try and see if it works, thank you

[GerdW]

Hi Fritz,

what does the context help tell you when you move the mouse over this broken wire?

Your PID probably outputs a scalar value. Graphs don't accept scalar values - as you can see in the context help!

Either create an array from your scalar PID outputs or use a chart instead…

[Pritz1]

How do i change the graph to double datatype? i cannot seem to figuyre this out. I have tried using the chart is the chart time dependant? i need my PID display a signal opposit to the input of the PID, and i am not that much concerned about the history.

[Pritz1]

Hi Gerd

the contrext help tells me the following

" You have connected two terminals of different types. The type of the source is double[64-bit real(~15digit precision)]. the type of sink is waveform (DBL)."

As i asked earlier will the chart be time dependant?

[GerdW]

Hi Fritz,

will the chart be time dependant?

A sarcastic answer: yes, it is time dependent as it plots new data when you supply new data…

LabVIEW comes with a lot of example VIs. And I know there are examples explaining how to use charts and graphs!