Acquire different types of analog signals with PCI-6221 and SCC-68

[DanSS]

Hi,Properly an easy task, but for me it has already resulted in many frustrations, which I hope some of you can help me get rid of. The problem is that I have a pci-6221 and a SCC-68 and that I have to get some analog measurements triggered by a shaft encoder. From the shaft encoder I have a maximum of 2048 counts/s ( 2rpm ),  and every  time I get a trigger signal I want to measure the other analog signals ( 2 x temperature,  1 x strain and 2 x voltage). Until now I have tried to do this by a sequence in a for loop but this is not nearly fast enough to do this acquiresation, and it results in delayed measurements. (Something to do with CPU power I guess?)  I’m all new in Labview and I hope some of you can give some hints on how to do the task, or even if it’s not possible to do so.  My temperatures are measured by a 2 x SCC-TC02 modules and my strain are measured though a SCC-SG24 which work individually.  Pls check the program which is attached and suggest. Anything is welcome.  DanS

[Hillman · Accepted solution]

Hi DanS,

Thanks for the post! 

So on every counted edge of the encoder you want to trigger the DAQ for other tasks?

If so, I have the perfect example - see attachments. 

If not, could you please explain the problem again...

Kind Regards,

*edit, forgot to mention you would need to add triggering, using the DAQmx trigger node

Message Edited by Hillman on 10-21-2008 02:00 PM

[DanSS]

Hi,

 First of all thanks for the example, which helped a lot. We have tried to set of more channels, and it seams to work(2 x temp & 1 x strain from Measurement And Automation (NiMax)). One thing we haven’t quite figured out yet is how to remove the max number of counts (buffer size)?? I have attached the modified and if someone has a good proposition on to how we make that infinity, please let us know. All suggestions we be appreciated. The labview version attached is 8.5  DanS

[Hillman]

Hi DanSS,

Im glad the example helped out.

Im afraid thats a limiation, you cant have an infinate buffer size! 

The number of samples you require for you buffer controls this.

Why do you require this?

Kind Regards