All charts have the same basic flow to them. Some have loops, jumps, or enclosing steps that include whole other charts, but the flow is always the same:
- All charts start at their begin step. The begin step can define initial values for variables in the chart's scope. These initial values are defined as expressions.
- Flow always moves downward out of chart elements, except for links, which can move flow in any direction. When a transition splits into 2 or more, they are evaluated left-to-right.
- When flow hits a step, that step is started. The step continues to execute until the transition beneath it becomes true. If there is no transition beneath a step, the step starts and is told to stop as soon as possible. In practice, this means that an action step's onStart and onStop scripts will be run, but no timer scripts.
- When any End step is activated, the chart stops.
Interaction and Monitoring
While SFCs are run in the gateway, Ignition has tools to help you interact with and monitor charts in the client. There is a chart monitor component that you can use to see the status of your SFCs in the client, there are scripting tools to start, stop, pause, and resume charts from the client, and you can send operator input to a chart with scripting functions.
Here are some examples of common paths or loops to get you started thinking about your process. You can combine these steps in any way, and create charts large or small.