Grafcet to ladder conversion

medbadr Posted messages 2 Status Member -  
mamont Posted messages 1 Status Member -

Hello everyone

I am new to the RSlogix500 software and I would like some help to convert a GRAFCET into ladder language (course or example).

Thank you in advance and see you later!

4 answers

  1. Bluescam
     
    Here is a simple method for Grafcet / Ladder translation
    Xn=step number
    tn=transition
    /=negation
    Xn=[Xn-1 & Tn + Xn] & (/Xn+1)

    Be careful with "or" and "and" transitions
    there can be several steps or transitions in "or" or "and"

    example= with 3 steps
    Step1=[step 3 and the one or more transitions before step 1 + step 1] and not step 2.
    and so on.

    The init step should never be the first one written in the ladder
    use an internal bit written as follows
    init or /init activates the init bit. Use this bit for all the initial steps of your grafcet
    It only activates once during the first scan

    We always write the grafcet first and then the outputs are written at the end
    As in telemechanics
    Preliminary (Input processing, module initialization, etc.)
    Chart (Grafcet)
    Post (outputs)
    I name my internal bits that I use for each step like this step1= X1, step2=X2
    When I search for a step in my program, I only type example X1

    For Allen Bradley PLCs
    I create 3 base files there can be several grafcet files but I always keep one that is posterior
    One preliminary file
    one Chart (Grafcet) file
    one Posterior file
    There must be only one place where an output is activated
    If an output is activated in several places, it complicates the diagnosis
    Good luck
    32
    1. Jp
       
      This method is valid if we compile the GRAFCET in reverse. There is a risk of having 2 active steps in the same scan if it is compiled from step 1, 2, 3, etc.

      I recommend the approach by "lanfeust54" which eliminates the risk of having 2 active steps at the same time.
      0