About implementation of IEC 61131-3 IL operators in standard microcontrollers

The paper presents various solutions for a Central Processing Unit (CPU) of Programmable Logic Controllers (PLC) developed on the basis of three typical microcontrollers from the families MCS- 51, AVR and ARM with the Cortex M3 core. The control program for these CPUs was developed in an Instruction List (IL) language that was in conformity with recommendations of the IEC-61131-3 standard. The most important issue that had to be resolved was translation of original commands in the IL language into own programming languages of the mentioned microcontrollers. The paper demonstrates that the commands of the IL language can be translated into fragments of runtime programs via procedures developed in the C language. The results achieved from all competed experiments make it possible to conclude that it is possible to design an efficient CPU, competitive in terms of the speed and time of the program execution, with use of standard microcontrollers.