GX Developer Non Linear Analog Input Problem

[chandrapaul]

Hi,
i have a pressure sensor (range 0-10 bar) and its output is 0-20 ma. but the current vs pressure curve is non linear such as.

pressure current
0bar 4ma
5bar 8ma
7bar 12ma
8bar 16ma
ect

the output current is not linear with the pressure increase. how can i scale this non linear output current in gx developer?

waiting for our help...

Thanks

 

[g.mccormick]

Can you create a polynomial curve in excel and then use a math instruction in gx developer?
Does gx developer have math instruction?

 

[chandrapaul]

yes there is math function available. can u please explain how to make polnimical curve and how to scale using math instruction.

Can you create a polynomial curve in excel and then use a math instruction in gx developer?
Does gx developer have math instruction?

 

[doomsword]

yes there is math function available. can u please explain how to make polnimical curve and how to scale using math instruction.

He's probably saying that you need to enter your x and y values into Excel and try polyfit, which will create an equation approximating data you put in.

for example, y is pressure, x is current

y= x^2+x+1

You need to create a program which will take x value (current) and calculate what's y (pressure) for that current, using equation excel generated for you. Could be some tricky polynomial though, might need some trimming or so.