I am facing problems reading measurements from DAQ card

[Waqas Ahmed]

I have connected some vibration sensors to my system through NI USB 6009 DAQ card. by analyzing the signals in labview, mostly it shows analog signals with 50 Hz frequency whereas frequency should vary upon triggering sensor. Our electrical power system is based on 50Hz, do DAQ card catches that frequency? Can anyone please help me in this regard??

thanks in anticipation.

Regard's 

[crossrulz]

The DAQ will register whatever in on the input signal.  It is likely your cabling is picking up the 50Hz.  Is the cable sheilded?  Is it running near a power source or cable?  You might need to apply a filter of some type.

[Waqas Ahmed]

yes the cable was shielded, even though i plug the cable in the DAQ without any sensor attached still it shows a signal of 50 Hz. what kind of filter it could be, any idea?

[REDS]

Hello Waqas,

You can try out some test to rule out some possible causes.

1) Rule out the voltage source: Try to measure a constant voltage from a battery and see if the issue remains. You can also do a short circuit between the analog

input and the AI GND. You should be able to see ~ 0V.

2) Try another USB cable and on a different USB port. Sometimes something as simple as a cable can make your life harder.

3) Try it on a different computer.

4) Try another devices on that same computer: Do you have other USB DAQ cards that you can try on that same computer? If you see noise with those other DAQ cards as well, it indicates there's a problem with the computer.

[Waqas Ahmed]

Thank you Daniel, thats so nice of you for giving me such a valuable advice. i have replaced existing DAQ with another and now its working properly.

Regard's

Waqas Ahmed