Ladder Logic Language(Ladder Diagram)

   

           

              Ladder Logic language is a PLC programming language, means  by which the user communicate information to PLC. Appearance of the Ladder Logic Language designed as a wired relay system, so it termed as a Graphical Programming Language. It is a symbolic set instruction used to create the controller program (representation of contacts and coils are the basic symbols of the ladder diagram). The corrective arrangement of these symbols made possible to create a desired control logic that is to be entered into the memory of the PLC. Ladder program prepared for a specific function is composed of symbols of contacts and coils and it is also called contact symbology .The Ladder Program controls the output based on input conditions. The control is done according to what is is referred by the ladder rung and the rung is consist of set of input conditions, represented by the contact symbols, at the end of rung output is represented by the coil symbols .Each contacts and coils are represents with an address number and which identifies  what is being evaluated and controlled.