Stepping voltage up or down base on comparison.

[me_tiger]

Hi guys,

I'm relatively new to Labview and I'm trying to automate flowrate control using a NI USB 6343.

The flow input data goes through a formula whos value is compared against a required value. What I want is to to either increase or decrease the voltage in steps of .01 to the flow meter based on whether the actual value is greater than or less than the required value.  Ultimately, I want to have a program that will adjust the flowrate to keep both values relatively equal.  My current program has a case structure with a boolean operated by the greater (>) function but I don't know how to add or subtract from the existing voltage value to the flow meter.

Some insight would be much appreciated.

Thanks in advance

[dragaoerrante]

Hi me_tiger.

I hope I understood corectly your question. In my opinion, the better way to acomplish this kind of issue is using a shift register. So you can store dynamicaly the last value you used in the comparison. I prepared a simple example of that for you.

Just let me know if I misunderstood your problem or if you got the solution.

Bests regards

Leo

[me_tiger]

Leo,

You understood correctly. I want to use the dynamic last stored value to make the comparison.

Could you please reupload the example for Labview 2009? or is there one available on the example database.

Thanks.

[leonardolt]

Right now!

Here it is.

Best regards

Leo

[leonardolt]

By the way... both dragaoerrante and leonardolt are the same person, me.

Leo

[me_tiger]

Thank you again.

I'm going to try fitting my information into the vi and i'll let you know how it all turns out.