SM43JR20 flow meter project

[Van]

I am using the example project provided in Unilogic for flow totalizing and everything proves out except the low end of my Linear conversion is still passing data.  20 mA (1023) passes 200gpm, and half signal, 12 mA passes 100gpm with no issues. 

4 mA should pass 0; but I am still getting data to my "Total gallons per minute", when I put 1-4mA through with my Fluke signal generator. This seems to defy logic as 0-4mA should not be passed!

Any ideas on this?  

 

[kratmel]

Try simple solution - add net with Compare FB

If MI2 < 204   then MI3=0;

If MI2 >=204 and MI2<=1023 then use Linearization FB (you use it in net4) ;

If MI2>1023 then MI3=200

Last net MI3 stored to DW1

[Ausman]

And Van, welcome.  FYI, the program you are using is Visilogic, not Unilogic.  Just letting you know, as incorrect referencing could cause confusion because it is a totally different system from Unitronics.

Kratmel's answer is the solution, but the reason as such is that Linearisation will continue to do it's instructed outputs if input parameters go outside the supposed maximum or minimum.  this is especially confusing if using 4-20ma inputs.

You may also like to get this to help with your learning:

https://forum.unitronics.com/topic/3540-linearization-calculator-for-all/

cheers, Aus