Speed Sensor Acquisition and Measurements

[damienclmt]

Hello guys,

I'm working on a testbench for traction motors. The goal is to make an automatic test sequence. At the moment, I don't have any problem with making a sequence.

When I try to make the acquisition of the speed sensor signals. It's typically 2 square signals phase shifted. On these 2 signals, I need to measure the phase shift (in time) and the overlap (in time). A draft (Capture.PNG) is attached to this topic to illustrate what I'm talking about.

So, I developed a VI using 2 simulated signals shifted and I succeed making the calculations I described above. Perfect!

The problem is when I use the real signals (acquired by AssistantDAQ) as inputs, the VI doesn't work anymore. The values are completely false. I don't understand why because both signals look clean on a graph but I do have some doubts about the acquisition.

I use a NI-9220 to read both signals.

- Acquisition mode: Continuous samples

- Samples to read: 3.5K

- Rate (Hz): 35 KHz

I would be super grateful if anyone can help me.

Nice day,

Damien

[caillotantoine]

Hi Damien, 

Do you only have access to a 9220? 

Otherwise I advise you to use counter acquisition with edge detection on your signal. 

Here is a link to help you on that way : https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P9qCSAS

Best regards, 

Antoine

[damienclmt]

Hello Antoine,

Thank you for your reply.

After reading the article you adviced me, I think that I need to buy a NI-9204 or NI-9435.

Then, I can measure :

- Pulse width

- Two-Signal Edge Separation

What do you think?

Regards,

Damien