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stanthe1man

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About stanthe1man

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  1. 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,

     

    X=Current analog input value linked to an MI

    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.

    https://www.dropbox.com/s/kdpn0mooa9qxmuq/mf pressure.vlp?dl=0

    1. stanthe1man

      stanthe1man

      Hello Kikis,

      Many thanks for your reply.

      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

      ladder.

      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. Kikis

      Kikis

      Hello Stan,

       

      You can use the formula command from the math menu.

      I think it should look like the picture attached.

       

      ff.PNG

  2. 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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