(A/B Function Block Diagram) Do something only if true

[Epy]

Ironically, I have never done any function block programming in Logix5000 itself, but I have to draw out a program for it.

My question is, what do you use to do something only if true?

I.e. I want to set a value to true if another value is >14, but also it should be set to false if that value is <10. If I simply use a greater than block, my value will get set to false as soon as it drops below 14. How can this be accomplished?

Attached is the equivalent in ladder logic.

Thanks for your help!

 

[Lancie1]

Use the LIM comnparison instruction with 14 as the Low Limit and 10 as High Limit, followed by an OTE for B3:0/7.

Also for easier understanding, you could use two comparison instructions in parallel branches: If F8:28 < 10 OR F8:28 > 14 then OTE B3:0/7. This rung logic will turn on B3:0/7 only when F8:28 is less than 10, or f8:28 is greater than 14.

 

[Epy]

Thanks for your reply, but I don't think that's exactly what I want.
Basically:
If input > 14 set bit to true
if input > 10 and input < 14 then keep existing value (do nothing)
If input < 10 set bit to false

 

[Lancie1]

I think this meets your requirements. It is not a function block, however.

 

[Epy]

Thanks very much. I think that works too and I can write that in function block form. Thanks again.