Is there any limitation in state space series connection ?

[avi2008]

Hi ,
I develop a simulation model using control design toolbox, but a have a problem with connecting my state space models. 

I have modeled a 11 subsystems in state-space and after I connected them with cd_series (ss and ss) two by two. When the arrays of the vector exceed dimension of 50x70 I have received the message:

Memory is full
the top level VI "namevi.vi" was stopped at unknown on the block diagram of NI_linSys_LinSys Conversion.lvlib:CD Convert TF to SS(LinSys).vi

I modeled the same subsystems by creating transfer function instead state space and all worked well.
I also modeled this in matlab and I have no problem with models connection.
If I look in task manager, the LabView increase the allocated memory with 500MB compared with matlab which allocate just 100MB.

Does any have o clue if it is any limitation of control design packet or where I am wrong?

Thank you very much for any suggestion.

I'm looking forward to your answers.

[Aldo_A]

Hi avi2008,

At this point, I am unsure if it is because of a control design packet limitation. It will help if you can post both versions of your application (using sate-space and transfer function) so we can analyze exactly how this is being set up. Can you post your code? In addition, what LabVIEW + CD&SIM Module version are you using?

[avi2008]

Hi Aldo,

I'm attached my file in a zip file.

My ss models are transformeted in constants in block diagram. I put one sample for state space ex_with_ss and the othere one with transfer function in ex_with_tf. The others are just for connections.

The tests are made in LabView 2009 (with its version of module control design) and in 2011 with the same result.

I'm looking forward to your answer.

Best Regardes,

Laurentiu Aioanei

[Aldo_A]

Hi Laurentiu,

Thanks for providing us the code. From our initial scan, as you stated the memory resources LabVIEW utilizes for your sate-space method grows until LabVIEW runs out of memory to use. Looking at your code, the subVI IndModelConnection.vi and the concatanation of your subsystems using Build Array.vi is a good place to begin troubleshooting this issue. My suspicion is that that specific array is growing out of bounds.

Try optimizing the way you are using Build Array.vi in your IndModelConnection.vi and see you continue to get the same error.

If Build Array is not the culprit, I recommend that you use the VI Profile Window tool to get a better understanding of your code and be able to isolate the memory issue to a specific subVI: http://digital.ni.com/public.nsf/allkb/9515BF080191A32086256D670069AB68

I look foward to your reply.

[avi2008 · Accepted solution]

Hi Aldo,

I'm looked into the subVI IndModelConnection.vi and the problem isn't there. The VI series is blocking when try to transform space-state in transfer function model.

Anyway this was un intermeeded stage of my model. What I can not find in Control System module is arbitrary interconnection of models.

Is it possible that this model to miss the VI which constructs the aggregate model for a given block diagram interconnection of dynamic system models?

Can you tell me if there is any VI or VIs which can do this functionality, in this module?

I look foward to your reply.

Laurentiu Aioanei

[avi2008]

Hi Aldo,

I solved the problem. I made myself interconnection model and I tested.

It's a pity that Control Model doesn't have this functionality implemented.

Best Regards

Laurentiu Aioanei