Conversion from SFC to Ladder logic

[plcnovel]

hi All
Is there an easy way to convert SFC written program into Ladder Logic automatically? I am in urgent need of doing it. Or if some one can tell me how to do it? Thanks in advance

 

[dchartier]

Hello Plcnovel;

I know of no automatic conversion from SFC to Ladder code, maybe someone else here has more information on such products.
Here is how we do it by hand (for example, when we use SFC as a design tool, and force ous students to do things the hard way...)

You will need 3 functions, or files or sections of Ladder (depends on the platform you will program) to implement the conversion of the Steps/Transition diagram:
1) the first will detail the combination of Transitions that will make a Step active and inactive (a Step becomes active (latched) when the preceding Step is active,and the preceding Transiion becomes true; it becomes inactive (unlatched) when the following Transition becomes true)
2) the second will detail the conditions that will make each Transition true
3) the third will will detail which actions are taken by the system when a Step is active(bits Set/Reset, values moved, subroutines called...)
I am looking for English documents on SFC to ladder conversions for you; all I have with me now are in Fraench. I will post them as soon as I find them.
Hope this helps,
Daniel Chartier

 

[SimonGoldsworthy]

Give some more background as to why you need to do this. SFC is a graphical method of describing a process and the tools used usually enable the user to monitor the progress of a sequence using the original graphical description. If you convert to ladder you will throw all of this convenience away. In the Siemens S7 environment, for example, I'm not aware of any method of automatically converting to ladder (and I wouldn't want one either)

 

[dchartier]

Hello again:

Here are a few sites I googled just now:

http://www.eod.gvsu.edu/~jackh/books/plcs/chapters/plc_sfc.pdf#search=%22SFC%20to%20Ladder%20conversion%22

http://www.canadu.com/hjhtml/plcs14-20.html (at the bottom of the document, under SFC implemented in Ladder logic)

Hope this helps,
Daniel Chartier