cancel
Showing results for 
Search instead for 
Did you mean: 

converting voltage into pressure

ihebz1
Member

converting voltage into pressure

Message contains an image

Hey guys I'm working on this LabVIEW Arduino interface  project I'm trying to measure  the pressure of a pump(max pressure of the pump is 70kpa) using an mpx5700dp sensor  .. my problem is I need to convert the voltage into pressure and display it on the

waveform using this transfer function .... can someone help me undertand it pls 

 

 

 

 

.transfer function.PNG

 

 

10 REPLIES 10
altenbach
Knight of NI

Re: converting voltage into pressure

Well, it's a simple linear formula (until it falls apart at high pressures), so all you need is implement the math given in the picture using three diagram constants (slope, offset, excitation voltage). What have you tried? 

ihebz1
Member

Re: converting voltage into pressure

Message contains an image

the problem is  I didn't understand it I made the interface  but I didn't know how to get the slope the excitation voltage and the offset  the maximum pressure of the pump is 70kpa convert lab.PNG

altenbach
Knight of NI

Re: converting voltage into pressure

Message contains an image

Just change the constants to the values from the picture. Zeroes are not useful.

 

Of course you need to solve the formula for P(Vout), given the constants.

 

altenbach_0-1652802860893.png

 

 

ihebz1
Member

Re: converting voltage into pressure

the offset voltage is 0 because it is linear but the sensitivity I didn't get is what I'm supposed to put 

altenbach
Knight of NI

Re: converting voltage into pressure


@ihebz1 wrote:

the offset voltage is 0 because it is linear but the sensitivity I didn't get is what I'm supposed to put 


That sentence makes no sense in so many ways! Did you look at my picture?

 

Also note that you don't need the separate pressure indicator if you show the digital display of the chart. We can typically offer much more specific help if you would attach your VI

crossrulz
Knight of NI

Re: converting voltage into pressure


@ihebz1 wrote:

the offset voltage is 0 because it is linear but the sensitivity I didn't get is what I'm supposed to put 


Read the transfer function straight from the data you already gave (ignore the "error" part):

Vout = Vs*(0.0012858*P+0.04)

 

So solve for P (basic algebra):

P = ((Vout/Vs) - 0.04) / 0.0012858 = ((Vout/Vs)-0.04)*777.726 = 777.726*Vout/Vs - 31.109

 

So your gain is: 777.726/Vs

and your offset is: -31.109



There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
"Not that we are sufficient in ourselves to claim anything as coming from us, but our sufficiency is from God" - 2 Corinthians 3:5
ihebz1
Member

Re: converting voltage into pressure

from where  the 777.726 came from ,, also -31.109

ihebz1
Member

Re: converting voltage into pressure

Message contains an attachment

 

proland1121
Member

Re: converting voltage into pressure

 


@ihebz1 wrote:

from where  the 777.726 came from ,, also -31.109


it's literally just algebra, he even wrote it all out for you.  did you get enough sleep last night?

Tags (1)