Speed measure with DAQ, how to override the noise

[kkpraksa]

Hello.

I try to measure spped using the counter input. My VI didn't work, so I look at the singnal I get from the encoder and I saw, I get a lot of noise in my signal. That's why program shows wrong values. I connect my signal between PFI8 and DGND on my DAQ 6212. My encoder (torque transducer) gives me 60 pulz/revolution. Is it possible to nullifythe noise with program, or there is a problem with ground. I tried many different ground options, but didn't work

Hope you have any idea.

Thanks a lot.

Simon

[stockson]

Dear Simon,

I simulated a 6212 device on my system and I created a task and confirmed that for ctr1 you should use PFI8 and the corresponding ground is DGND.

Unfortunately there are no filtering options for digital input on the card.

I also don't really understand what kind of noise are you experiencing. Is this noise generated by the encoder or does it appear on the input? What are the logic levels of the encoder? Could you post your application?

Regards,

[kkpraksa]

Hello Mateusz. Thank you for responding me.

You can see my signal taken from scope and check my vi file. Noise causes regulator of the motor I drive. If regulator is switched off there is no noise and if I turn my motor by hand, I get correct values of velocity, but when I turn on the controller, I get full of noise in my signal, so DAQ card reads all those noise as many signals, so it displys velocity much greater than it's real. I moved my daq card away from controller as much as possible and used coaxial cable, but noise still appear. I hope you have any idea.

I hope you don't mind, because notes in my vi are written in my language. I just wrote them, that I can see what I was doing.

Regards. Simon

[AnalogKid2DigitalMan]

What is the make/model of the motor?

What type of circuit/board is driving the motor?

Is the power supply for the motor separate from the encoder with no common ground connections?

Can you post a sketch of how everything is wired up?

-AK2DM