PLC ladder Exemple and PLC programming27 Jan 2010 06:59 pm
PLC State Diagram Transition for Traffic Lights Control system
A sample set of equations seen in See State Transition equations for the traffic light example, see a traffic light state diagram.
Each state and the transition must be assigned a unique variable name. (Note: It is a good idea to note these on the diagram)
These are then used to write equations for the diagram.
The transition equations are written by looking at each state, and then determining which transitions will end this state.
For example, if ST1 is true, and crosswalk button S1 is pushed, and S2 is not, then transition T1 will be true. The state equations corresponding to the state equations in the previous State Equation method, except that they now only refer to transitions. Recall, the basic form of these equations is that the State will be where it is already on, or it is turned on by a transition. The State will be off if the exiting transition occurs. In this example the first scan had his own transition, but it could also have been put into the equation for T4. (more…) Tags: activity sequence diagram, Allen Bradley PLC, plc inputs and outputs, PLC ladder Exemple, plc ladder logic diagrams, PLC programming, programmable logic controllers plc, state machine diagrams, structured text plc plc, wiring diagram
