interfacing labview with other apps

[ngm.604]

Hello there,

We've built a game controller as part of a student project and are seeking real time simulation using labview. I tried the usual I/O text method where labview writes the data and the other app ( autodesk maya in this case) reads it. This provided a maximum reading rate of 5 Hz. The I/O process is too slow. Is there a way to interface the 2 apps directly?

Thank you in advance for the help.

Nick

[Ray.R]

5Hz?

Did I read correclty?  5Hz?  Wow...  That's unusually slow..

That aside..  Is there an API or dll's that you can communicate directly from LabVIEW?

What environment is available to interface between the controller, LabVIEW, and AutoDesk?

R

[sgregor249]

Maybe a local TCP connection

[ngm.604]

hey guys,

this whole thing is out of the scope of my experience so i m gonna tell you what i need to do. i ve built a exoskeletal robotic arm controller. i have around 27 output pins that i need to read into a 3 d model for simulation of its application. Now i figured i d do the dac in labview and write the angular measurements to maya where i can control the model in real time. Now maya can be scipted with MEL( maya embedded language),python, and it allows for API scripting for plugins. Just let me know if you got what i need to do and we ll pick it up from there. Sry for the noobness. 🙂

[DFGray]

For input, a DAQ card is probably easiest.  Select it based on the following criteria:

1.  How often do you need to collect data?  Be aware that most DAQ cards have a single analog to digital converter (ADC) and multiplex the inputs.  This reduces the per channel acquisition rate by the number of channels you are acquiring (27 in your case).
2. Do you need simultaneous samples?  Most DAQ cards do not do this (inputs are scanned, so there is a time delay between samples).  You can get a sample/hold accessory to convert the input to effectively be simultaneous.  Or you can pick a DAQ card that has a sample/hold.  You can also get one with multiple ADCs.
3. How much can you spend?  Multiple ADCs and sample/hold circuits add cost.  Even if you would like simultaneous input, you can often work around scanned input in software.  This is especially true if the scan rate is fast compared to how often you need data.

I am unfamiliar with Maya, so cannot offer more than general suggestions for interfacing:

1. Can you export the model so the LabVIEW 3D control can use it directly?  I suspect not, but if you can, it would make things easier.
2. Does Maya have and ActiveX or DLL interface.  If so, use it.  This is probably your easiest and fastest method.
3. As previously mentioned, does Maya support TCP/IP.  If so, you can use this.
4. As a last resort, write results to file and have Maya read them.  This will be comparatively slow, but should be much faster than 5Hz.  File I/O is typically megabytes/second.

That about exhausts my knowledge.  Good luck.  Post some pictures if you get it working!

[ngm.604]

Thanks DFGRAY. I'll try and it look into all the methods you mentioned. Just curious. Is it possible to model directly in Labview instead of using two programs. That 'd be ideal.

Nick

[DFGray]

There is a 3D control/indicator in LabVIEW.  You can find quite a few examples of its use.  It has undergone some fairly major changes in the last few versions, including some integration with CAD programs.  However, I have never used it and really can't comment on it.  There are quite a few people on these forums who have, however, so someone should be able to answer your question (Ben, where are you ).

[Ray.R]

If I'm not mistaken, by using 3D in LabVIEW, you won't need Maya.  And thus, no interfacing issue.  🙂

[ngm.604]

I managed to get it up to 22Hz which is great for smooth hand motion I think. The problem is its not consistent and highly dependent on multithreading. I won't even go into giving the task priority cuz i m in over my head as it is. I ve been looking at the NI softmotion and how to integrate a solidworks 3d model into LV and control it. That would be great if it were real time control. Unfortunately, the information I went through was oriented towards play back simulation. If I'm mistaken please let me know because it's easy to pull off. Other than that, It's pointed out to me that MEL ( maya embedded language) which i m using for my scripts is slower than python. So if I translate my code to P, I may have a better simulation than the one I have right now.

cheers guys.. n thanks for the replies. I really appreciate it!