COMPACT PLC WITH EVENT-DRIVEN PROGRAM TASKS EXECUTION

The paper presents modified idea of program execution in the Programmable Logic Controllers (PLCs). Instead of serial cyclic execution is proposed event sensitive cyclic execution. Proposed approach to program execution allow for selective execution of program blocks or tasks provided calculation condition for this part has changed since last time. Proposed method can be implemented as software modification or as hardware accelerated solution. The most important part of the idea is task or subprogram triggering condition computation. Different method of program optimization are discussed. Finally hardware implementation of event triggered system is presented.