Boots – shoes – and leggings
Patent
1990-02-09
1992-12-01
Ruggiero, Joseph
Boots, shoes, and leggings
364DIG2, 3649269, 364949, 36496576, G06F 1546
Patent
active
051684420
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a programmable controller in which sequence control of a machine tool is executed by ladder processing which employs a microprocessor or the like. More particularly, the invention makes it possible to modify a ladder program and makes high-speed ladder processing feasible.
BACKGROUND ART
An ordinary programmable controller uses non-volatile memory means such as a ROM storing a specific ladder program in order to make possible sequence control conforming to a controlled system. If the controlled system of the programmable controller is a machine tool, it is required to create a ladder program in such a manner that it will not be necessary to change the existing ROM whenever there is a modification in a specifications of the machine tool. One method of achieving this is to make the portion of the ladder capable of being modified as a subroutine, and storing the subroutine in a rewritable EROM (erasable read-only memory). In modifying a ladder or adding to a ladder, a plurality of ROM boards are prepared in advance and these are plugged into, say, a mother board of the programmable controller, thereby making it possible to modify or add to the contents of a ladder.
In comparison with a case in which the ladder program is stored in temporary storage-type memory means such as a RAM and backing up the RAM using a separate power supply, the above method of storing the ladder program using only a conventional ROM is advantageous in that erasure of the program due to a power supply abnormality or the like can be prevented in reliable fashion. Conversely, however, the speed at which the program data can be read out of the ROM is lower than with the RAM, and therefore the operating speed of the machine tool is restricted by the ladder processing speed.
Though a programmable controller has been considered in which joint use is made of an ultraviolet erasable-type EPROM (erasable and programmable ROM), all of the data stored in single units in such case is erased simultaneously when the data is rewritten, and therefore it is impossible to modify a portion of the ladder. Moreover, another disadvantage is that a ROM unit must be extracted from the mother board on account of this erasure. With conventional programmable controllers of this kind, many problems are encountered in terms of modifying the ladder program and operating an NC (numerical control unit) efficiently.
DISCLOSURE OF THE INVENTION
Accordingly, the present invention has been devised in order to solve the foregoing problems and its object is to provide a programmable controller in which a programmable ladder sequence is stored electrically in a rewritable EEPROM and an NC can be operated efficiently by making joint use of a RAM capable of high-speed processing.
In accordance with the present invention, there is provided a programmable controller capable of storing a ladder program and of modifying and editing the contents thereof, which includes programmable read-only memory (EEPROM), capable of being electrically rewritten, for storing the ladder program stored in the EEPROM, and a random-access memory (RAM) to which program data is transferred from the EEPROM when the ladder program is executed.
Accordingly, the programmable controller according to the present invention is such that if a management program and ladder program are stored on an EEPROM board on the maker side at the time of shipment, editing and modification of the ladder in the ROM can be carried out on the user side whenever necessary without battery backup.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating an embodiment of the present invention, and FIG. 2 is a block diagram illustrating the basic construction of a programmable controller.
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will now be described in detail with reference to the drawings.
FIG. 2 is a block diagram illustrating the basic construction of a sequence PC (programmable controller) used in conjunction with an
REFERENCES:
patent: 4566061 (1986-01-01), Ogden et al.
patent: 4638452 (1987-01-01), Schultz et al.
patent: 4677541 (1987-06-01), Singhi
patent: 4916640 (1990-04-01), Gasperi et al.
Ikeda Yoshiaki
Kuwasawa Mitsuru
Fanuc Ltd.
Ruggiero Joseph
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