The basic idea behind a Sequential Function Chart is to run one section of the PLC’s code – and then to switch over to running a different section of code at the appropriate time. A simple analogy would be a flow chart.
The sections of the PLC’s code are divided into “Steps” – and moving from one Step to the next is controlled by a “Transition” element.
The code within the Steps – and within the Transitions – might have been written using any of several different methods. The original programmer might have used Ladder Diagrams, Structured Text, or Function Block Diagrams (in any combination) when setting up the Sequential Function Chart.
If you need to understand this type of programming, we have troubleshooting exercises available – all based on our hands-on Boot Camp training approach.