OAT Tachometer Incorrect RPM

[MiamiVipul]

Hello:

I'm using OAT toolkit and trying to figure how to fing the RPM of my rotating shaft.

I have NI4472 card and 6601 counter on PCI, running Labview 7.1  and OAT 2.1 on XP. I collect encorder pulses through my counter 1pulse/rev. In all my OAT examples, I get an incorrect RPM. I have tried same examples using analog tacho setup to void the complication of 4472/6601. But still I see a large RPM, compared to my 120 RPM rotational speed.

I have carefully gone through Brian's "OAT Tachometer Incorrect Results" posting too. Even at that posting, there was no clear solution suggested.

I have attched my VI and if anyone of you know the solution, please let me know. I'm using Labview 7.1, so please bare that in your mind if you would like to attach any VI that I can use.

Thanks a lot.

Vipul.

[Travis_W]

Hi Vipul,

Can you explain the behavior you're seeing in more depth.  For instance, in the other post that you mentioned, the problem was due to the counter task being set up for simple edge counting instead of buffered event counting, thereby providing data to the OAT VIs in an unexpected manner.  Are you seeing that your indicated RPM varies inversely with your shaft speed?

I also noticed that there is a modified the VI in the code you posted named "oax_Config DSA and TIO Channel (Single Shot) 4472.vi" changed from "oax_Config DSA and TIO Channel (Single Shot).vi."  Can you attach a copy of this VI so we can check how it has been modified?  The sample clock timing VI that this is called inside this code is very important for reading counter data in a format that the OAT VIs expect.  Do you see the same behavior in the original example program with the original version of this subVI?

Thanks Vipul.  Let me know if there is something I'm missing, or if there's anything else I can do to help out.  I want to make sure that your issue gets resolved.

Have a great day!
Travis W