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Old November 7th, 2018, 02:21 PM   #1
United States

remullis is offline
Join Date: Oct 2012
Location: Georgia
Posts: 140
cpt function and doing the math for silo capacity

I am working with plc5.

I am using the CPT function but getting errors.

The level of the silo is inputed at F51:031. The silo cuft is 3393 with 30' overall height. I need this computed and then I will multiply the Bulk Density to get total tons in the tank.

This is what I have:

(F51:031-0)*(3393-0)/(30-0)+0 ( this is in error)

(Input 17 in tank -InputMin 0) * (ScaleMax 3393 cuft capacity ScaleMin 0)/(InputMax 30 tall tank-InputMin 0) + ScaleMin 0
(17-0)*(3393-0)/(30-0)+0 = 1922.7 cuft of material in silo at 17 in a 30 tank where the cuft of the tank volume is 3393.

Any help would be appreciated.

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Old November 7th, 2018, 02:54 PM   #2
United States

mscholz is offline
Join Date: Jul 2010
Location: TX
Posts: 37
Try using | (Right above the enter key on your keyboard) instead of / for divide.
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Old November 7th, 2018, 02:55 PM   #3
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GaryS is offline
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Join Date: Aug 2003
Location: Lancaster Pa.
Posts: 883
First question is the bottom of the silo flat or is there a cone ?
The formula for volume of a cylinder is
V=Pi R2 x Height
use that to calculate the volume from the flat bottom up
then if you have a cone calculate the volume in the cone by the level
V=Pi R2 x (Height / 3)
add the 2 together
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Old November 8th, 2018, 02:05 PM   #4
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remullis is offline
Join Date: Oct 2012
Location: Georgia
Posts: 140
The | for divide solved my error for the equation. I am able to scale the silo's that are linear (flat bottom). I have figured the silo capacity for a non linear with a cone but of course with the current method above that I am using, when I get to the lower range of the silo I am off some tons.

I have lot's of tanks with varying sizes. Is there a way to scale nonlinear possibly just for the cone volume. I can do the logic to control how I read once it gets down to the cone hopefully. I am trying to avoid programming multiple level points in the PLC5.
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