This paper proposes a method of developing ladder logic diagram for PLCs via S-method (a structured method of programming routines). From flexible manufacturing industry point of view, engineers can easily understand the operation of the complicated system and have better control on industrial automation system by applying S-method. By practicing this, highly dependent on vendor for operating the system also can be eliminated. This paper describes detailed steps of the method that converts from description of the system to a ladder logic diagram involving a series of systematic steps. A case study on pick and place section, the KUKA system which is implementing the S-method is discussed in paper. © (2012) Trans Tech Publications, Switzerland.