Why NI 9234 create error 20308 when reading pulse measurement of my tachometer?

[Ihab]

Hello,

I am monitoring a machine condition using a triaxial accelerometer and optical tachometer for speed. I have 8 pulses each revolution.

Please find attached my screen shot for the error and the VI. It runs few seconds and stops.

Please try to find what am I doing wrong? 

Many thanks in advance for your help and support.

[MaggieAggie]

Hello Bibb, 

You are receiving this error because you are not crossing the reference levels often enough. The reference levels, described in the help files here, help determine one cycle. If your reference levels are too high and your signal is not crossing them, it will not be able to determine the measurement interval of one complete cycle. Also, if your frequency is too low, it will not cross often enough as well. 

[Ihab]

Hi, 

I am Ihab

Do I need to add single tone to the VI?

I am haveing 8 pulses per revolution, the shaft sunning by 250 rpm ,  I should get 2000 pulses per minute - is that what you mean by low frequency?

[MaggieAggie]

Hello Ihab, 

2000 pulses per minute would only be a frequency of 33 Hz, which I would consider low. I found another forum here that is seeing the same error. However, they did not see the error with frequencies over 17 Hz.

Are you able to increase your frequency? If that does not work, I would check your reference levels to make sure your signal is passing it every time.