# stanthe1man

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1. ## Kikis    stanthe1man

Hello,

I replied to your post but since every post should be checked by the moderators before posted, there is a delay.

So I'm pasting what i wrote to you here....

If the pressure  is linearly proportional to the analog input voltage, then you could use linear interpolation formula and floating point registers (MF).

Floating registers are also known as real numbers and it's the best way to deal with fractions.

Since the linearization function within Visilogic can't be used for MF registers, you have to do it step by step using simple mathematical functions.

LINEAR INTERPOLATION FORMULA:

Y = ( ( X - X1 )( Y2 - Y1) / ( X2 - X1) )

Where,

X1,Y1 = First co-ordinates

X2,Y2 = Second co-ordinates

X = Target X co-ordinate

Y = Interpolated Y co-ordinate

If your 0-10V analog input is 12 bit (0-4095) then,

X1=409

X2=3726

Y1=0.000055

Y2=1000

Y= Pressure result displayed on the screen

I created an example for you, you can download it from my dropbox.

1. Hello Kikis,

Unfortunately I don't think that the result will be displayed as required.

I do have a formula that is known to work, but I don't know how to present it to Unilogic

Here is the formula:

(expression written in Compact Logix) apparently!

0.00000241*(Vac_Gauge_V**6.552)+(1.0000000e-022*(2.7183001**(Vac_Gauge_V**1.75)))-0.0002

where Vac_Gauge_V can = between 10.0v to 1.0v.

So assume it = 4.35v ,  the end result should display as this type of format - 4.2x10¯³ or 4.2x10-3

I know this seems a big ask but my maths skills are not good - I can't even get the equation into excel.

Any help would be wonderful!

Thanks

Stan

2. Hello Stan,

You can use the formula command from the math menu.

I think it should look like the picture attached.

2. ## Scientific Notation

Please could someone explain how I can display a 0-10v input signal as a pressure output:- 9.1v = 1000mb to 1.0v = 5.5 x 10-5mb ? I am using 1210 with latest Visilogic. My ladder programming skill is quite basic but I have managed to control and HMI a full high vacuum pumping system but need to display the vacuum levels in scientific notation. Any help would be great. Many thanks Stan
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