Sample PLC program SFC time based counter (Sequential Flow Chart)

Sequential Flow Chart is a good top-down programming language part of the IEC61131-3 PLCopen that shows the different steps in process control. Steps can have multiple actions and will stay active until transition is true, then the next step is activated. The different actions can be written in any language (ladder logic, structured text, continuous flow chart or even another SFC).

This is a simple program that waits one second and then increments a counter variable and repeats.

You can download and run it to start learning. Here's a link to the program: