Error adding the Recursive Kalman Filter to a block diagram

[Evan F]

Good evening,

When creating a new VI, you have the option to add already defined VI's to your block diagram. When I attempt to add the CD Continuous Recursive Kalman Filter.vi to a blank block diagram, the mouse cursor turns into a black circle with a diagonal line through it and doesn't allow me to add the filter. Another interesting property of this problem is I'm able to open up the VI out of the library C:\Program Files\National Instruments\LabVIEW 8.5\vi.lib\addons\Control Design\_Implementation and see it's block diagram with no problem.

Also, it seems that neither the CD Continuous Recursive Kalman filter nor the CD Continuous Recursive Kalman Observer are able to be added, and they both have a unique icon. I've attached a screen shot that shows what I'm talking about. They appear to have a blue'ish background with curved corners. I'm sure that means something, however I can't find the definition.

The screen shot doesn't capture the mouse cursor, so I'm not able to represent the circle with a line diagonally through it. I should also note that I read in the help that I need to have the LabVIEW Control Design Toolkit and the LabVIEW Simulation Module installed, which I assume I do have because I'm able to reach the functions. Also, it says to place the function into a Simulated Loop, which I believe I've done with putting it in a never-ending while loop (to get the same circle with a line through it).

Should I be able to add these two VI's to my own VI as is? Is a while loop not considered a "Simulated Loop"? Other than a reinstall of LabVIEW 8.5, is there anything you can suggest that will get these two functions working? If you need any additional information, please let me know and I'll respond back as soon as possible. Thank you very much for your time.

[Thoric]

Hi Evan,

Although I can't replicate your problem, as I don't have those specific vi's, I do have the "Continuous Linear Systems" vis which have similar blue background icons with rounded corners (I also do not know what this style of icon means). I can, however, place these with no problems into a blank vi.

Something to try:

Instead of right-clicking the mouse to show the functions palette, use the drop-down menu item View > Functions Palette. Then navigate to the vi's you're having trouble with. Right-click the vi and select "Place VI" from the shortcut list. Does this allow you to place the vi in your block diagram?

Alternatively, try selecting "Open VI" instead, then drag and drop the vi's icon from it's own front panel onto your block diagram. Does this work?

If that fails, also try  "Select a vi..." from the right-click functions palette menu and navigate to the location of the troublesome vi "CD Continuous......". Does this allow you to insert the vi at all?

[Evan F]

Thank you very much for your reply. Using the Place vi option has the same result (error circle). After opening the VI and trying to drag it's own icon to a blank space, it doesn't place it and skips the error circle all together. The Select a vi option also goes back to my friend the error circle.

After some more thinking, I become uncomfortable with the assumption that a while loop should be considered a "Simulated loop". Sure enough, my suspicions were correct. After further investigation, I found a Simulation Loop object under the Simulation category and had a smack forehead moment. It can even be seen in my screen shot! After placing this loop in the block diagram, I was able to insert the filter using all methods listed above once the cursor was inside the loop.

Thank you very much for your suggestions!

[Thoric]

Evan,

Glad you got this sorted out 🙂

And thanks for posting your solution, I'm sure others will find this thread useful in future.

All the best,