PLC sequential control design method

Sequential control design method is the basic idea of the system connected to the order of a working cycle is divided into several stages, these stages are known as step (Step). Sequential function chart (SFC) is mainly composed of steps, to the connections, transformations, transitions, conditions and actions.
Figure 1 is a diagram on how to take control of transport and the input and output waveforms, pressed the starting button I0.0 started 1th, belt, delay automatic start after the 6s 2nd transport zone. Press the stop button I0.1, stop 2nd transport zone, automatically stops after 5s, 1th conveyors. Figure 2 is S7-300 S7-Graph draw sequential function chart language.
Transport work was natural Division of 6s delay start running, 5s down, twin delay these 3 steps (see Figure 2 for S2~S4), and also set a initial step S1 waiting to start, the initial step in double wire frame representation.
When the system is in the stage where a step, said the step was activities. Green in the monitoring activities.
Each step is in the box to the right of the step to complete the action. R, s for the Q4.0 in the action reset and set, S2 d delays, but not use the timer to delay. The 6s delay when M0.3 becomes 1.
S3 Q4.1 n in steps for nonstorage, S3 is the active step Q4.1 1 status, Q4.1 is 0 when the inactive state.
Next step to the line. Used to line and directed perpendicular to the line of dashes to indicate.
That system by the current steps into the next signal might be called transition conditions, such as the Start button I0.0 is converted from the initial step to convert the starting delay step condition. S7-Graph ladder diagram and function block diagrams to indicate conditions.

N indicates the action type is stored, 0, 1 State and the State of the same.
Handbook of instruction can be seen in the action of S7-Graph

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