A method and system is provided for creating applications for one or more types of programmable logic controllers (PLCs). A open development kit (ODK) is provided that permits dynamic link libraries to be created and interfaced to a user application software and also to the interface layers of the various types of PLCs. The types of PLCs may include soft PLCs, slot PLCs, and hard PLCs and interface via slots of a personal computer platform. The ODK provides generic interfacing to the various types of PLCs and establishes the necessary operating environment structure to implement processing in either a non-real time and a real time mode. A single application package may then control and manage the various types of PLCs. Communication paths are provided from the PLCs to the ODK subsystem to the user application so that the application software is essentially indifferent to type of PLC involved.