Using SIT connection manager with large simulink models is extremely slow

Question

Hello,
I'm trying to use a large simulink model in LabVIEW but once the DLL is correctly generated and the SIT connection manager is invoked to explore the model sinks, sources and parameters, it takes hours to generate the model connections tree. Afterwards, when the connections tree is completed, it is impossible to handle it because every operation performed takes a lot of time and memory (i.e. to expand a block to see which parameters are inside).
The version of SIT I'm using is 2.0.3 with LabVIEW 7.1.
Is there anybody experienced with large simulink models and SIT?
Thanks and regards.
Ignacio Sánchez Peral
SENER Ingeniería y Sistemas S.A.
Control Systems Section
Aerospace Division
C/ Severo Ochoa, 4 (PTM).
28760 Tres Cantos (Madrid) Spain.
[email protected]
Tel + 34 91 807 74 34
Fax + 34 91 807 72 08
http://www.sener.es

Answer 1

The VI in the Driver VI called SIT Initialize Model.vi has an input called time step (sec) (-1: use model time step) which does what you want it to. It doesn't actually affect the time step of the solver used in the built model DLL, just the rate at which the main base rate loop actually runs in real time. In fact, base rate loop period would be a better name for this control. If you set it, you won't alter your model, but you will be able to adjust the rate of the base rate loop.
Simply create a control from this input terminal on your driver VI and fill in an appropriate period in seconds. Make sure to set this value as default in the control so that the Driver VI remembers it.
You will have to take into account that your model will still think it's running at the time step it was compiled at. So your model simulation time and the actual wall clock time won't match up.
Jarrod S.
National Instruments