topic Re: Im creating a simple PID controller, however i cannot graph the output in LabVIEW

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

Pritz1 — Fri, 02 Oct 2015 12:38:21 GMT

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

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

natasftw — Fri, 02 Oct 2015 12:47:05 GMT

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.

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

Pritz1 — Mon, 05 Oct 2015 07:21:51 GMT

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

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

GerdW — Mon, 05 Oct 2015 08:18:18 GMT

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…

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

Pritz1 — Tue, 06 Oct 2015 10:55:22 GMT

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.

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

Pritz1 — Tue, 06 Oct 2015 11:01:09 GMT

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?

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

GerdW — Tue, 06 Oct 2015 11:19:51 GMT

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!