A two-step TIA Portal GRAPH sequencer on an S7-1500: actions, interlock, supervision and transition, then the causes of a step that will not advance.
Station and line PLC split, a PackML state machine in Structured Text, torque tool error proofing, andon stops and downtime that blames the right station.
Build a working SFC in Studio 5000: steps, transitions, action qualifiers, the SFC Execution settings that decide what happens on a restart, and S7-GRAPH.
PLC sequencer programming with SQO and SQI, why position zero never fires on the first transition, and how to drive a rotary indexer from it.
What the PLC first scan bit S:FC does when the controller goes to run, and where it earns its place: power-on timers, resets, sequencer defaults.