| 摘要 |
PURPOSE:To efficiently access only the heating part of an instruction word at the time of retrieving a user program memory to increase the retrieval processing speed by adding bits indicating the instruction word length to the instruction word itself used for user program generation. CONSTITUTION:A programmable controller consists of a CPU 1, a system memory 2, a user program memory 3, an input/output memory 4, a work memory 5, an interface 6, and input/output circuits 7 and 8 which are connected through an address bus AB and a data bus DB. The overall length of the instruction word is written in the rear end part of the read-out first word at the time of accessing a user program. Consequently, this value is added to a program counter to immediately determine the next access destination. Thus, the processing time required for retrieval of the instruction word length in the program is shortened, and a part other than the heading of the instruction word is not accessed to improve the processing efficiency. |
