Differential equation

[DaneDukic]

I need to implement this differential equation in one vi. Output would be this dtr/dtau, all other are inputs I have from other vis. Have a big problem how to pass last value of tr to calculate new one. I need this for student purposes, made everything in matlab and all works fine but here in labview I need to use shift register but the values are not passed well.

If anyone have any suggestion it would be great.

Thanks.

[Kyle97330]

It would be best if you could post a VI so we could see it.

However, might I suggest possibly using a feedback node?

[DaneDukic]

Tr is the right side of shift register and Trp is left side of shift register. And here is also my whole project. I need to implement these 3 equations.

[alexderjuengere]

If you have acces to LabVIEW Full or Professional Development Systems, 

you might take a look at the shipped examples in

..Program Files (x86)\National Instruments\LabVIEW 2016\examples\Mathematics\Differential Equations - PDE

and also the labview help e.g.:

http://zone.ni.com/reference/en-XX/help/371361L-01/TOC115.htm

[DaneDukic]

I have only student trial version.

[alexderjuengere]

however, as kyle pointed out, you can implement differential equations in LabView using feedback nodes or shift registers

in chapter 12 of this book, it is shown how to implement ODEs with plain LabView (no Toolkits involved)

I don't suppose this book to be completely available at books.google.com, but there are some example .vis from the authors website at: http://www.geho-labview.de/172.html

for example, this:

can be written as:

which is available as Aufgabe 12.1.zip (389,0 KiB)

it would be nice, I you posted your example .vis in a lower version of LabView e.g. 2014, then more people can look at your code.

[DaneDukic]

Here is a version for 2013 of my whole project. Also I have a matlab simulink same project and everything working fine there. When I try to make 1 on 1 copy in labview something doesnt work. In simulink I have only 1/s integrator as output parameter of my equation and feedback to input. Also I will check your answer and try to figure out and I will post my results.

[alexderjuengere]

Maybe its also a good idea to us .zip instead of .7z  - but anyway:

that won't work, I guess

what are you trying to do?

Looks like you want to sum up several values of Tr? How many values of Tr do you want to sum up?

You say: 

In simulink I have only 1/s integrator as output parameter of my equation and feedback to input

What does a 1/s integrator do?

 What is value do you expect for dt?

[alexderjuengere]

I deleted the Express.vi in CoilMetalParts.vi and output Tr directly.

When I Multiply Tr with an assumed value of dt = 0,1 and add this value with Tr init = 295,15

I get the following for Ta and Tw: