4 Step Ladder Instructions 4.2 Sequential Function Chart (SFC) In automation, we always need electric control to work with mechanical control for an automation control. The sequential control can be divided into several orderly steps (or stages). Each step has its actions that should be completed and the transition from one step to another normally requires some criteria. The action of the last step finishes when all criteria is true and the beginning of the next step will clear the actions of the last step. This is the concept of designing a sequential function chart (SFC). Features: DVP-PLC Application Manual 4-2 1.
No sequential design is required for constant step actions, and PLC will automatically execute the interlocking and dual outputs among all status. An easy sequential design is the only thing required to make the machine work normally. 2. The actions in SFC are easy to understand, adjust for a trial operation, detect the errors and maintain. 3. SFC is a type of diagram editing. The structure of a SFC looks like a flow chart. Every No. of the step relay S inside the PLC represents a step, equal to every processing procedure in a flow chart. When the current procedure is completed, the program will move to the next step according to the set transition criteria.
Therefore, you can repeat the cycle and obtain the result you desire. 4. See the SFC chart in the right hand side: The initial step S0 transfers to a general purpose step S21 by making the status transition condition X0 condition true. S21 transfer to S22 or jumps to S24 by making X1 or X2 true. In step S25, X6 will be true and the chart will return to S0 to complete a cycle. The cycle and be repeated to reach a cyclic control. 5. Next are some basic icons for drawing SFC in WPLSoft SFC editor. SFC: S0 X0 S21 X1 X2 S22 S24 X3 X4 S24 X5 S25 X6 S0 Ladder diagram mode. The icon indicates that the internal editing program is a general ladder diagram, not a step ladder program.
Initial step in SFC. Applicable for S0 ~ S9. General step. Applicable for S10 ~ S1023. Step jumps. Used for a step to jump to another non-adjacent step. (Jumping up/down to non-adjacent steps in the same sequence, returning to initial step, or jumping among different sequences.) Transition condition between steps. Alternative divergence. The same step transfers to a corresponding step by different transition condition.