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Celcius to Fareheit conversion

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I'm using a M90-R1 PLC.

A section of my application is used to convert degrees Celciust o Fareheit. The formula is Tf = (9/5)*Tc+32.

Is the M90 can handle numbers with decimals? For the 9/5, since the result is 1,8 i used an integer number 2 for the calculation... It give a approximate conversion...

How can i improve it?

Thank you for your help!

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  • MVP 2023

An old trick for PLCs that only have integers is to use a "virtual decimal". Multiply the celcius value by 18 and add 320. Your fahrenheit value will have a virtual tenths place which you can work with and display by setting the numeric format to xx.x. Otherwise, you can divide the answer by 10 and get rid of it.

I checked this out on my slide rule. It works great!


Feel free to try it out on yours. Don't forget to add your exponents or you won't get the right answer. Or you could program the Jazz to do it.

Joe T.

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