Sequencer logic. Ladder or SFC?

I am working on a machine with many pneumatic cylinders which cycle in a certain sequence. The PLC used is fully IEC 61131 compliant. I can program the sequence logic using ladder or SFC. I am very familiar with ladder logic but new to SFC. Are there any compelling reasons to use SFC over ladder logic? Any experience with using SFC in North America?

Not North America, I'm afraid...
I now use SFC wherever possible for this type of stuff. Easier to visualize and add in extra steps. Fault handling becomes a breeze.

Fault handling becomes a breeze.

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How does using SFC make fault handling a breeze?

Use the right tool for the job. SFC (sequential function chart) is a natural for sequences. If a process is hung up, you can see it visually in usually one compact screen. If you write the same thing in ladder, you have to scroll up and down which is a pain.

godfrey said:

Use the right tool for the job. SFC (sequential function chart) is a natural for sequences. If a process is hung up, you can see it visually in usually one compact screen. If you write the same thing in ladder, you have to scroll up and down which is a pain.

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I always put a "tattletale rung" at the beginning of my sequence ladder which has the bits for each step. So you can quickly and easily see where it is in the sequence.

Fault handling


Two reasons for me. In the first example, it's very easy to isolate and deal with specific problems, Stopping the feed conveyors in this case. It's very easy to prompt how to recover, and make the actual recovery.

In the second expample, each STEP maintains its own step timer, ie no need to start a specific timer. It's fairly self-explanatory that the sequence will pause here until there's a box at exit, or 2 seconds have elapsed.

I wrote this same program in ladder before my preferred plc platform supported SFC. I made the decision to re-write when it did, and it's so much easier to maintain.

Without wanting a backlash from anti-double coilers, the fact that STEPs are run in total isolation, not only is it acceptable, but I'd say encouraged. [Seeks shelter]
Pp

I did the same question when i was studying SFC method and I was programmin with SFC method a traffic ligths on S7300 PLC from siemens it was a paint in the *** because I tried to programm everything step by step, my program did whatever it wants jaja so, I just had to understand what the timers do and it was so easy. If your program needs just a combination logic use ladder diagram. if it doesn't you use SFC.