RPM as a Function of Crank Angle (optical encoder - counters)

[Fird]

Hi Ceties.

Yes, your response won't help much at all (I'm joking).

For the moment, we are using USB 6009 to test the VI.  However, we will change it to another card which better and fit for this VI.

 Thanks.

p/s : Do you have any idea with the error message below:

------------------------------------ 

Possible reason(s):

Source terminal to be routed could not be found on the device.

Make sure the terminal name is valid for the specified device. Refer to Measurement & Automation Explorer for valid terminal names.

Property: Start.DigEdge.Src

Property: Start.DigEdge.Edge

Source Device: Dev1

Source Terminal: OnboardClock

Task Name: _unnamedTask<58>

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Thanks!

-Fird 

[aNIta B]

Hi Fird,

     Could you please tell me how you have your device wired?  What pins on the 6009 are you using?  If you switch to another device, could you please post which device you are switching to and how you have that wired?  Additionally, regarding the error you posted below: it is likely related to this KB . Have a great weekend!

[Fird]

Hi Anita, 

I have two USB 6009.

As for the device connection, the Analog Input for Pressure is connected to AIO (i'm not using differential).

The trigger and also clock are using the encoder which the clock source is connected to Dev1/cntrl0 while trigger Dev2/cntrl0 and connected to Z-line (top Zero) and line A of encoder resepectively.

Btw Anita,

As i read some of the posts here, they said I cannot use counter (Dev2/cntrl0) as a trigger input.  And some suggestion was given in previous post:

Re: Start Triggers for counter tasks.

The regular Start Trigger can only be used for counter output (pulse generation) tasks.  For input (measurement) tasks, you would need to use an "Arm Start" trigger.  Trouble is, you can only configure it using the DAQmx Trigger property node, like the ones where you set retriggerable = True.   However, as far as I know, the "Arm Start" trigger (used for counter input tasks) can't be set as retriggerable.  I don't think retriggering a finite acq could easily get you what you want anyway though.  It doesn't leave you enough read time between finishing one acq and getting the next trigger.   In sum, use the DAQmx Trigger property node to configure an "Arm Start" trigger with the appropriate inputs (signal source, active edge, etc.) 

Do you have any idea on this matter?

Thanks.

-Fird- 

[Fird]

Hi ALL,

My VI didn't stop the acqusition part and always running the program. It suppose to go on the next case structure once the data already acquired. Please see the picture below:

 

Thanks a lot.

- Fird - 

[aNIta B]

Hi Fird,

      The information that you had posted from previously in the thread is correct.  Are you needing retriggerable aquisition, as was discussed?  Or are you only needing a start trigger?  As for why you're not leaving your case structure- it's hard to tell from the picture you posted, what are your cases?  As well, have you used highlight execution to see where in your program you are getting caught up?

[Fird]

Hi Anita,

What I need only the start trigger.

I havent try to use the highlight execution yet. Will see it soon.

Will get back to u later.

Thanks a lot.

- Fird - 

[yesil16]

Hey Fird

I would like to acquire a data of pressure and also angle from engine just as you done and would like to get some ideas from you.I will do the same thing with you . We will use incremental encoder to get angle of crank and trancducer to take pressure data.

First of all can i use CI Angular Position to measure angle or for using CI Angular Position do i need an absolute encoder ?

Thx for helping!!!

[James-D]

Hi yesil16,

To answer your question, you can use the CI Angular Position setting on the DAQmx Create Channel VI to measure angular position with an incremental encoder.  

I hope this helps!

Regards,