dc/ analog/ sine waves voltage generation

[ouchie_85]

Hi Guys,

I would like to get some help here. I've developed this vi to generate dc values, analog values and also generate frequency. But my problem is I keep on getting error after the DAQ Write. Can someone help me to correct my vi or enlighten me. Really need it urgently but i cant solve it. Thanks guys. Really appreciate you guys help.

[ouchie_85]

Sorry guys , there is a double post.

[ouchie_85]

Hi, is there any one out there can help me with my vi? thanks

[Ana P]

Hi ouchie_85,

You can’t have multiple analog output tasks in one device; however you can group all the channels in one task. I believe this error you are getting is because you are starting two analog output tasks in your vi. This knowledge base has information on how to program simultaneous analog output tasks in the same device. Also, have a look at this post that discussed a similar situation. Can you use one task for all the channels? What device are you using in this application? I believe that you must be using one of the Analog output cards, NI-67xx, in which case this developer zone could be helpful.

[ouchie_85]

Hi Ana,

Thanks for your reply. Currently I am using the NI PCI-6723. The thing is that i wanted to generate is an array of DC Values and also 9 frequencies at the same time. What i have been doing is to put the DC values under a task and the frequencies in another task as the DAQMx Write configuration is different as for DC(DBL) and the Multiple ones(Wfm). And usually the error occurs after the DAQWrite for the frequncies task.

Cheers

[Dennis_Knutson]

The fact that you have dc and ac signals is irrelevant. The type of identical tasks you are prohibited from doing is analog output.

Your VI is very difficult to read (actually, nect to impossible) because the wires go every direction, underneath, on top, etc. I'm sure you can clean it up a lot and then combine all of your signals (ac and dc) into a single task. 

[ouchie_85]

Hi Dennis,

Sorry for the messy Vi. Quite new in it . Trying my best to improvise and improve. Could you enlighten me more about the thing you mentioned about combining them under one single task. Can i know how to combine both the DC and Waveform Frequencies together since they are of different type. How should i make it possible? Using Build Array? or any methods? Thanks

[Dennis_Knutson]

Since you are already passing a waveform array to the DAQmx Write, create a waveform for each dc signal and add those to the array. I'm not sure if the number of samples matters. Try it with a waveform type with a single element in the Y array.

Message Edited by Dennis Knutson on 04-08-2008 09:12 PM