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Logaritmic formula

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I'd like to have a formula math function with a logaritmic scale.

The formula is


U is a analog input 0-10Vdc

P is a pressure calculated by the Jazz PLC


My question how to program this formula in the U90 Software?



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The Jazz controllers unfortunately cannot support complicated math functions. They are limited to basic calculations that use 16 bit MI values that can work with values from -32768 to +32767. It would not be possible to calculate such large values within the Jazz controller using logarithmic operations.


If possible I would recommend utilizing one of our Vision Series controllers, such as the V120. This will allow the use of the more powerful software that can work with 32 bit numbers as well as more complicated formulas.

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  • MVP 2023

If you're feeling really brave, look up the Taylor series for an exponential calculation, write a long program calculating sums and squares, and work with virtual decimal points.  There is one 32 bit register you can use with special functions.  I did this years ago to calculate cosines in an M90 before the V120 existed. 


As Alex points out, you are limited by the valued a 16 bit signed integer can hold.  You'll have to run some sample calculations to see if it's even possible.


The Jazz wall strikes again.  The easiest thing to do is buy a V130.


Joe T.

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