TechTalk : Range Check Logic in RSLogix 5

I believe we have all done this kind of logic before but I wanted to put it down on my web as a reference for myself and to whoever needs it. Reference for advance programmers and introduction for beginners.

Overanging and underanging a value in the PLC logic can lead to various undesirable result(s). I am not really going to list all the negative aspects of it as it all depends on circumstances and requirements.

This short logic below shows how to prevent the process value from going under or over the undesirable ranges.

  • Rung one ensures that if the PLC is reading anything below 0 (from register N9:1), the register N45:6 is set to have a value of 0.
  • Rung two ensures that if the PLC is reading anything above 163 (from register N9:1), the register N45:6 is set to have a value of 163.
  • Rung three LIM function block ensure that if the value in register N9:1 is within 0 and 163, then assign the actual value reading in register N9:1 to N45:6

Xybernetics Range Check Logic in RSLogix5

 

Cheers!

n1849778
About the
I am a software developer in Calgary, Alberta, Canada with passion in getting my fingers in any new technology. I started software development when I was 10 years old and have never looked back. Now with well over 35 years of software development, I wanted to share some of these key knowledge with the people of the world in the wide web.