Showing results for 
Search instead for 
Did you mean: 

Control & Simulation Loop failed to compile

Dear Forum Members,


I have a problem with a Control & Simulation Loop program (attached) that just doesn't compile & run.  I believe that the problem is associated with the 'Feedback Node' at the bottom of this Control & Simulation Frame since if this is taken out the program will run ok.


Can anyone please advise me if this 'Feedback Node' is incorrectly used or in violation of anything.  I have tried various ways to overcome the problem i.e. initialising it at the start but nothing works.  The error message that I received just says "VI failed to compile".


Appreciate any help with this.

0 Kudos
Message 1 of 6

Attached the vi this time

0 Kudos
Message 2 of 6

Hello bunnykins, 


The Feedback node really isn't a supported function in control design and simulation. The behavior you're reporting, and the work around are both documented in the know issues of the module here



A Feedback Node on a Simulation Diagram causes the VI to fail to compile
The Feedback Node does not make sense semantically within a Simulation Diagram, due to the fact that most ODE Solvers will execute the diagram multiple times per iteration and may need to reject steps and try again, filling the Feedback Node with bad data.

Workaround: Use the Memory block from the Simulation Utility palette. If a delay of greater than 1 is desired you can chain multiple memory blocks in sequence.

Reported Version: 8.5    Resolved Version: N/A    Added: 07/31/2010
Applications Engineer
National Instruments
CLD Certified
0 Kudos
Message 3 of 6

Hey, Could you please tell me in what other situation does a control and simulation loop fail to compile ?



0 Kudos
Message 4 of 6

I am working on control of Quanser 2DOF Helicopter model. I'm facing problem to run the VI since it is showing an error (as shown in Error page.png). Can anyone guide how to approach and run the VI.

Download All
0 Kudos
Message 5 of 6

Hi aditi,


Since this thread hasn't been active for more than a year, you'll get better visibility (and a better chance of help from the community) if you post a new thread with your question!

William R.
0 Kudos
Message 6 of 6