SFC (Grafcet) programming with RSLogix 500

Hello everyone,

Please forgive my ignorance, but I am new to the field of PLC programming. I would like to know if RSLogix 500 could be used to program an SLC 5/02 using SFC programming techniques and would that entail the purchase of optional modules with the RSLogix 500 software package.

Thank you everyone.

Mohoch Megabar

As far as I know, directly programming SFC is for Allen-Bradley only possible with RSLogix 5000, which will not do for you.

However, SFC is in fact a design method and not a programming language. You can manually translate an SFC to ladder logic, which isn't all that difficult. In fact, I find it rather easy. As long as you have the possibility to make a memory, beit monostable or bistable, and have boolean logic available, then it's possible to use SFC as a design method. I have used it to design relay driven circuits, electronic circuits, pneumatic circuits, and yes, also PLC programs. I've used this technique on Allen-Bradley SLC5/03, Philips PC20 and Siemens S7-200, all of which have no SFC programming package available.

Some websites describing the translation of SFC to ladder are:

1. VTI St-Pieter (Beringen, Belgium) which is unfortunately in Dutch. Look at the first figure in chapter 3.6.2.
2. Ecole Polytechnique (Montreal, Canada) - French language. Page 26 to 28 give you the translation of a simple grafcet (or SFC). Unfortunately, the translating is done a little hasty. In the ladder diagram you have to change E1 and E2 to X1 and X2 respectively, and then it's correct.
3. Hugh Jacks book on PLCs, chapter 20, which seems to be based on Allen-Bradley PLCs and is in English.

I hope this info helps you in your search.

Kind regards,

Just so you know

jvdcande said:

As far as I know, directly programming SFC is for Allen-Bradley only possible with RSLogix 5000,...

Click to expand...

SFC programming is available on enhanced PLC-5s.

Doug,


thanks for the info. It so happens I only work with SLC5/03 and CompactLogix (apart from other brands) and have no knowledge whatsoever about PLC5. I didn't find this info on the AB website either.

Kind regards,

Hello Doug,

I want to thank you for your guidance and your help, your information is valuable to me. I too believe it is rather easy to duplicate SFC using Ladder logic. As I understand it I think I have to define several bits (one per step) such that each one is reset when the following becomes set. The transition defined on the top part of the ladder logic program will then establish the switching from on step to the next.
Once again thank you so much for your valuable help
Mohoch Megabar

Thank you everyone for your support and help

Mohoch Megabar

Here is a video I put together that shows how to start with something very similar to SFC and put it in RSLogix 500 ladder.

http://www.youtube.com/watch?v=rCa_U6YATTA