PROGRAMMABLE CONTROLLER USING SEQUENCE INTERPRETER APPROACH AND CONTROL METHOD OF PROCESS USING PROGRAMMABLE CONTROLLER

PROBLEM TO BE SOLVED: To provide a PLC using an external control data technique. SOLUTION: The work memory 24 of the programmable logic controller (PLC) is loaded with only one instruction at a time from the PLC's load memory 22 of the PLC which contains the entire instruction set to control a process. Each instruction has a format which contains at least one option code which must be evaluated to be true by a PLC interpreter before the corresponding instruction is executed. If the interpreter evaluates at least the one option code to be false, the instruction is not executed and a succeeding instruction is transferred from the load memory 22 to the work memory 24 and then its corresponding option codes are evaluated. COPYRIGHT: (C)2006,JPO&NCIPI