High frequency Labview-Simulink Interface

[Shazlan]

Hi,
I am building a Simulink and Labview model to work with each other using SIT. However, before I even begin, I would like to know whether this Labview-Simulink interface will or will not be able to run at a relatively high frequency - possibly around 80 Hz? Also, if there is any tips or hints on how to make the program run faster, such as run Simulink and Labview on different computers which are connected via LAN, etc., they are highly appreciated. And if this is of any help, I am using a P4 2.0 GHz with 256 MB of RAM computer.
Thanks and have a nice day!

[Carl L]

Lan,
A large part of the speed will depend on the size of the model. The CPU would need to be divided between simulating the model and doing the updates, but since you are looking for a high speed it is probably a simple model. I ran a very simple model and tested to see how often I could receive values from the NI Sink in the model as well as write to a parameter of the model. In this simple setup, I recieved updates from the NI Sink at a rate faster then 1000 Hz (less then 1 ms per update on average), and writing to the parameter happened a bit slower at about every 25 ms. Since it is windows these numbers are only averages and individual iterations will vary.
If you want to provide the model with a stimulus as it is running from an external input (like a DAQ
card) then you will want to use a real-time system. This functionality is also part of SIT, where you use Real-time Workshop to build a dll and example VIs for running the model on a LabVIEW Real-Time target. Building a DLL in this way you can still use the same user interface to view the parameters and values in the model, but the inports and outports of the model will be connected to hardware. In this type of simulation the rates can be significantly faster.

Carl L
National Instruments
www.ni.com/ask