Detecting Fast Rise in Voltage

[jeffdillon]

I am monitoring pressure in a high vacuum chamber with LabView 7.1 and an NI
USB-6008

The vacuum level measurement is essentially a voltage between 0 and 10V. 0V
= low pressure, 10V = atmospheric pressure.

When a fast leak is detected (e.g. 1/2 volt rise (x), let's say, in 1/2 sec
(y), I want to write to a digital port. X and Y would be input parameters to
the algorithm.

When this is working, the system will be automatically shut down if a fast
leak is detected.

I have everything working, except the algorithm to detect a fast leak (fast
rise in voltage).Currently the VI consists of a DAQ Assistant in a While
loop, N=1000 Samples to read, 1 KHz sampling rate. I thinking of storing
moving average values (I have running average VI samples), and looking for
trends (?) within the specified timer interval y. I'm not quite sure of the
best way to approach this. It almost sounds like integration?

Jeff

[Ankita]

Hi Jeff,

I would suggest taking the moving average and comparing the difference in consecutive moving average readings every loop iteration. If it is higher than a threshold value, it is a fast leak else it is not. You can use a shift register  in the while loop to store the moving average value from the last iteration of the loop.

Regards,

Ankita