Transforming A Circuit Diagram - Siemens SIMATIC S7-200 Manual

First programming exercise

4.6 Transforming a circuit diagram

4.6 Transforming a circuit diagram
How do you transform a circuit diagram into a PLC program? Rotate your circuit diagram 90°
to the left. Your power rail will then appear on the left, with the grounding rail on the right. In
the middle you will see the switching elements of your circuit. The circuit logic of a machine
(e.g. time relays or flip-flops) which used to be implemented by wiring together switches,
auxiliary contactors and control contactors, etc., is now handled by the PLC. Control
elements such as input switches, selector switches, etc. on the input side, and power
contactors (such as motor contactors, polarity reversers, valves, etc.) on the output side
cannot be replaced by the PLC.
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Getting Started - Beginners
Training Documents, 07/2007, A5E01031470B