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one sample interval delay?

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I have been using a custom LabVIEW RT code for a model-in-the-loop application, where I execute (1) one AI read, (2)one model step and (3) one AO write in one iteration of a timed loop.

 

I am thinking about moving to NI VeriStand instead of my custom LabVIEW RT application. From what I have learned so far, in VeriStand, the AI read and AO write will occur in the primary control loop, while the execution of the model step will occur in the model loop. Does this mean that there will necessarily be an additional one sample time delay in the feedback calculation compared to my LabVIEW RT application?

 

Also, can I execute the model loop with the same priority as the primary control loop?

 

Thank you.

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Accepted by topic author mvsiva

So by default, that is the behavior. VeriStand will write to the model imports and then allow the model to execute which reduces overall execution time. However, there is a setting that will cause the primary control loop (PCL) to write to the model, wait for model completion, and then read from the model. This help article does a great job of describing the different model execution modes: Understanding PCL Execution and Model Latency.

 

Additionally, if you're looking at moving to NI VeriStand, I would highly recommend speaking with your local sales engineer. They have a lot of expertise in understanding system requirements and making sure that you're moving to an architecture that will meet your needs. If you are unsure who your local sales engineer is, you can also call (888) 280-7645 to speak with one of our sales development engineers.

 

Hopefully this helps!

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Christine,

Thank you.

Siva

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