Implementing a transfer function without the Control and Simulation Toolkit

[sirius18]

Hello folks,

I am working on implementing a control system for a thermocycler. And for this purpose, I need a feedback PID control loop and a feedforward controller that reduces the load on the feedback control loop. We were able to implement the PID loop without the toolkit (using shift registers and such) but I'm not sure how to implement a feedback controller whose transfer function I have [(35s+1)/(0.0001s+1)]. 

Can I use a formula node and implement it with a C-code? I'm not sure how to do this in C either.

Any help is appreciated!

Thanks!

sirius18

[Chris-NI · Accepted solution]

Hi sirius18,

You may use the Formula Node to perform the math you mentioned, but it will not execute C code.  The syntax is similar though.  Here is some information on putting a formula into a Formula Node:

  Formula Node (help documentation) - https://www.ni.com/docs/en-US/bundle/labview/page/formula-nodes.html

For those who prefer C, one may write their code there, create a DLL, and then call their C function using a Call Library Function Node:

  Call Library Function Node (help documentation) - https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/functions/call-library-function-node.html

  Tutorial (overview) - https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YGZjCAO&l=en-US

  Example - https://forums.ni.com/t5/Example-Code/Calling-a-C-built-DLL-in-LabVIEW-to-Generate-and-Sort-an-Array...

Hope this helps!

Regards,

[Chris-NI]

On a side note - when looking into this, I came across what looks to be a very useful tool for performing math in LabVIEW:

  Math Node - https://forums.ni.com/t5/Example-Code/Math-Node-A-new-way-to-do-math-in-LabVIEW/ta-p/3494770

I've not used it myself, but some others here may have some input on this!