monitor a data for sudden drop

[Anonymous]

Hi everyone,

I have a control system that measures and controls the hydraulic
pressure in a chamber. I want to monitor pressure signal and stop if
it suddenly drops (or increases). Because this means hydraulic
leakage.

I have tried to use data delay. I have delayed data and compare it
with current value and connected this to a stop but it didn't work.
There is only one property of the data delay (history), and I changed
this value. but no use. Actually I'm a bit confused with the history
property also.

Do you have any suggestion?

My system is a computer based control system with NI internal card and
Labview 8.

[TroyK]

From what you have described I assume you are measuring one point at a time and plotting it on a waveform chart (as opposed to a graph).
Waveform chart has a history property, waveform graph does not.

I'm not sure that writing to the history property is what you need to do.

It might be easier to help you if you posted the code you are having trouble with.

I think you may want to store a few samples of previous data in a shift register and compare it to the current measurement.