Reexamination Certificate
1997-07-03
2001-09-18
Harrell, Robert B. (Department: 2758)
Reexamination Certificate
active
06290403
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a sequence program execution control system for executing a sequence program, such as an SFC (sequential function chart), that is expressed in a step format.
BACKGROUND ART
A ladder format and mnemonic format are typical expression methods for a sequence program that is executed by means of a programmable controller (hereinafter referred to as PC). Recently, however, a sequence program expressed in a step format, such as an SFC (sequential function chart), has also come to be used.
The sequence program expressed in the step format, unlike the ladder format, is not executed by scanning, but is executed step by step in regular order. When the execution of a final step is completed, the sequence program is finished through, and thereafter, the steps are repeated.
In some cases, the execution of the sequence program in this step format may be expected to be interrupted on account of a machine's failure, checkup of the machine in the middle of programming, etc. The execution can be interrupted either by the method in which the power source of the PC is turned off to restart the processing from the beginning or by the method in which the content of the sequence program is previously set so that the execution can be stopped in a predetermined position.
The method in which the power source of the PC is turned off, however, has a problem such that it requires time-consuming adjustment such as initialization of a machine before resuming a sequence program by reconnecting the power source. Further, in the case where the PC is connected to a network, the power source cannot be turned off without considering its effect.
On the other hand, in the case of the method in which the sequence program is preset for interruption, it is difficult to previously specify a spot at which interruption of the execution is required. Since troubles cannot be foreseen, the execution cannot be interrupted for inspection of faulty spots in the case of this method.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a sequence program execution control system capable of manually specifying one or two or more of a plurality of steps constituting a sequence program so that the specified step can be either interrupted or unexecuted, and the program is made to proceed to the next unspecified steps.
In order to achieve the above object, a sequence program execution control system according to the present invention comprises program storage means for storing a sequence program composed of a plurality of steps, an execution control means for executing the sequence program by the unit of step and in regular order to control the operation of a machine, step specifying means capable of specifying any one or two or more of the steps constituting the sequence program stored in the program storage means, and skip command means for enforcing the execution control means to skip the specified step to proceed to the next step.
Preferably, the step specifying means and the skip command means are respectively provided in the form of command keys to a manual input device with display screen connected to a numerical control device or an automatic programming apparatus connected to a numerical control device.
Further preferably, the manual input device with display screen further includes, respectively in the form of command keys, interruption command means for commanding the execution control means to interrupt the execution of a currently running step and maintain the resulting state without advancing to the execution of the next step, and execution restart command means for commanding the execution control means to restart the execution of the interrupted step.
According to the present invention, the execution of the sequence program can be interrupted at any desired step to start the execution of the next step or the execution of selected steps can be skipped without turning off the power source or without previously so setting the sequence program. Thus, inspection and editing can be carried out with ease.
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Onishi Yasushi
Saiki Yoshiharu
Fanuc Ltd
Harrell Robert B.
Staas & Halsey
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