Error 200429 on DAQmx Read

[Vicku]

Hi,

I am trying to use one AI, one AO and one Coutner Inputs to run on a PXI target with Simulation Interface toolkit. Currently SIT generated code for only AO and AI and to add a counter input we need to modify the subVIs. I have done that but I am getting the Error 200429 on the DAQmx Read vi for the AI channel. The same vi runs fine without the modifications for the counter input so it appeared to me as if there is something is wrong with the code that I added. But i checked the code that I added for the counter separately and it also runs fine. I am attaching a screenshot off the error message and all the vis. The error happens in the sinewave_IO IO Read.vi in the sinewave_IO.llb.

Any kind of suggestions would be highly appreciated.

Vivek.

[Vicku]

The screen shot of the error messsage is added below.


Vivek.

[Elizabeth W]

Hi Vivek,

I tried taking a look at your code but since I can't run it, there is only so much troubleshooting I can do.  Have you tried placing a probe on the IO Ref cluster being passed between the initialization VI and the read VI in the Base Rate Loop VI?  If you run the VI with a probe on this line, you can check whether a valid analog input task is being passed to the IO Read VI and hopefully narrow down where this error is occuring.

If you are able to try this out, let me know how it goes and I can help you with some more troubleshooting.

[pelle2005]

hi,

i have approximately the same problem (in write, not in read, but the problem is the same), and i would like to say how have you resolve it please..

[Vicku]

Hi there,

I reprogrammed everything from scratch once again and new code worked without this problem. The two versions look exactly the same to me and it is still a mystery for me as to why one works and the other does not work. I am sorry I cant suggest something really useful other than reprogramming at this point. If I find something in future I will post it here.

Regards,
Viku.

[Elizabeth W]

I'm not an expert on Simulation Interface Toolkit, so I'm not sure whether or not this is relevant to the problem you are seeing, but I thought I'd share it.  Take a look at the Known Issues section in LabVIEW Simulation Interface Toolkit 3.0 Readme Files.  It mentions the following known issue with real-time simulations:

"If you create mappings between a model DLL and only AI or only AO channels on a DAQ device, the driver VI returns error –200429."

I hope this helps.

[Vicku]

Hi Elizabeth,

Thankyou very much for your prompt replies. This specific issue of using only AO or only AI channels is not an issue in the code that I attached here as it has both AO and AI channels. Pelle if this is the case with your code then you can do one of the following two things:

1. Use a dummy AO/AI channel.
2. What happens is that the automatic code generation in SIT (the build file button in the hardware mappings tab) creates atleast one AO and AI channels irrespective of your using only AO or AI channel. So what you can do is you can manually delete all the refrences and DAQmx Vis that refer to that extra channel from the subVIs in <modelname>_IO.llb.

Regads,
Viku.

[pelle2005]

in my case, the problem was local variable. I use this for passing data and for not use too much wire, but i notice on another post that sometime local variable don t have the time to be write. I am very surprise on this, i think is a bug of LabView very strange and dangerous.

[Elizabeth W]

I do not know which post you are referring to, but please keep in mind that most problems with local and global variables are a result of incorrect usage by the user and not by a bug in LabVIEW.  You may want to refer to the documents linked below for more information on what I'm talking about.

Are LabVIEW global variables good or bad, and when is it OK to use them?

KnowledgeBase 28Q6L7B5: Why Does Using a Local, Global, or Shared Variable to Pass Data Between Para...

The bottom line is that local variables are easily misused and care must be taken to ensure that you are using them properly. 

[pelle2005]

Hi,

i do not want to speak badly about Labview. I have use the term "bug" because i use this in my "office slang" with my friends.

I have read on this topic

http://forums.ni.com/ni/board/message?board.id=170&message.id=180275&query.id=117394

that is better to not use local variable when is possible, and i have try to solve my problem with this guideline. The problem now is resolved.

However i will read the link to learn more about.