JP2009080736A - Plc construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform hot plug of an I/O module without stopping a production system controlled by a PLC, and to rewrite a running sequence program in response to the hot swap. <P>SOLUTION: This PLC construction method includes a step for plugging/unplugging an I/O module during the execution of a sequence program; a step for making a program tool automatically recognize the I/O module plugged or unplugged; a step for displaying the sequence program on a program tool screen and for correcting the sequence program on the display screen; a step for downloading the correction data of the sequence program to the PLC side; and a step for rewriting the running sequence program according to the downloaded correction data at the PLC side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sequence program and a PLC (programmable controller) construction method. More specifically, the present invention performs hot-swapping of I / O modules and rewrites the sequence program during RUN to enable plug and play. The present invention relates to a PLC construction method. Rewriting during RUN is to change the contents of the sequence program being executed in the PLC without stopping the PLC execution state (RUN) from the PLC peripheral device.

  The building block type PLC includes a CPU module and a plurality of I / O modules. The CPU module includes a CPU that executes a ladder diagram type sequence program (ladder program) in accordance with a system control program, a system control program, a sequence program, and various memories that store data such as CPU calculation results. Composed. The I / O module is composed of an input module, an output module, an input / output module, communication, positioning, a high-function module such as a counter, and the like.

  The ladder program is designed on a general-purpose personal computer loaded with an application for editing a ladder program. After designing the ladder program, the designer simulates the sequence operation of this ladder program on a personal computer, debugs the ladder program while verifying the simulation result, and transfers the completed ladder program to the PLC.

  This ladder program is directly created in a ladder language, or a mnemonic program is created in a mnemonic language and converted into a ladder diagram.

  Corresponding to the ladder program transferred to the PLC and stored in the memory, the CPU in the CPU module performs an input refresh process (a process of overwriting and updating the input data with a new one) for loading data from the input module into the memory. After that, the ladder program is executed once, and output refresh processing (processing for overwriting and updating the data output from the output module) for outputting the contents of the memory after the calculation to the output module is performed.

However, when adding or changing an I / O module during the execution of the PLC, it is necessary to stop the execution of the ladder program, download the ladder program reconstructed by the personal computer, and then restart the ladder program. Until then, there was a problem that the production system controlled by the PLC had to be stopped.
JP 2004-021446 A

  In the present invention, the sequence program is changed from the ladder diagram method to the sequencer circuit diagram (sequencer circuit diagram) method, so that the sequence program can be rewritten during RUN, and plug-and-play can be performed by hot plugging / unplugging the I / O module. As described above, the above-described problems can be solved by making it possible to implement additional changes of I / O modules without having to stop the production system controlled by the PLC.

  A PLC construction method according to the present invention is a PLC construction method comprising one or a plurality of I / O modules and a CPU module that executes and controls input / output of signals in the I / O modules according to a sequence program. Transmitting the data of the I / O module that has been hot-plugged during execution to the tool, correcting the sequence program on the tool screen based on the data, downloading the correction program to the PLC, The PLC side includes a step of rewriting the sequence program during the RUN according to the downloaded correction program.

  In the present invention, when an I / O module is added and changed to correct a sequence program, the I / O module is hot-swapped and the sequence program is corrected on the tool screen. The sequence program can be rewritten during the RUN using data corresponding to. Therefore, in the present invention, the I / O module is hot-plugged and the I / O module including the hot-plugged I / O module is inserted without the need to stop the production system even when the PLC is controlling the production system during execution of the sequence program. It is possible to change the control of the production system by executing another modified sequence program from the sequence program being executed.

  The above sequence program is composed of a plurality of program elements obtained by blocking each input / output signal and internal operation function in units of individual I / O modules, and each circuit element is connected with a sequence number and connected in a circuit. It is preferable to express the circuit diagram.

  According to the present invention, it is not necessary to stop the system even when the production system is controlled by the PLC, so that the control of the production system can be performed separately by hot-plugging the I / O module and rewriting the sequence program during the RUN. It is possible to change to the control.

  Hereinafter, a sequence program and a PLC construction method according to an embodiment of the present invention will be described with reference to the accompanying drawings. Referring to FIG. 1, 1 is a PLC, and 3 is a personal computer as an example of a PLC peripheral device. The PLC 1 includes a CPU module 5 and one or more I / O modules 7a to 7e. Reference numeral 7f denotes an I / O module to be added or changed indicated by hatching in the figure. The I / O module 7f is an I / O module that is added and changed to the PLC 1 by hot-swapping while a user executes a predetermined sequence program by the PLC 1 and controls the production system. The PLC 1 is communicably connected to the personal computer 3 via a USB or the like. The CPU module 5 incorporates a sequence program, an RUN rewrite processing execution program, and the like.

  This sequence program may be a ladder diagram type sequence program, but the sequence program of the embodiment is a block circuit type (sequencer circuit diagram type) sequence program shown in FIG. This block circuit type sequence program is composed of program elements A, B, C,..., E in which I / O modules 7a to 7e are made into block circuits for respective input / output signals and internal operation functions. Each program element A, B, C,..., E has a sequence number Sa, Sb. .. Is a sequence program represented by a circuit diagram with circuit connections Lab, Lbc,... Attached with Sc,. Note that the program element D in FIG. 2 is a program element D that is changed by adding the I / O module 7f, and this program element D is assigned a sequence number Sd, thereby changing the circuit connection of the program element. The The CPU module 5 executes the modified sequence program in the order of sequence numbers.

  The personal computer 3 includes a CPU that executes rewrite processing during RUN, a memory that stores a program for executing rewrite processing during RUN, a display 3a that displays information for rewrite during RUN, a keyboard 3b and a mouse 3c for processing operations, etc. And an interface unit with the PLC 1.

  In the above configuration, the user needs to add the program element D to the sequence program shown in FIG. 2 in response to the control change of the production system or the addition of a part of the system. In addition, when the I / O module 7f for executing the program element D is added to the PLC 1, the user connects the I / O module 7f to the PLC 1 by hot plugging without stopping the operation of the production system.

  When the personal computer 3 recognizes the I / O module 7f connected to the PLC 1, the personal computer 3 reads out the sequence program shown in FIG. 2 from the CPU module 5 after predetermined response communication with the CPU module 5, and displays it on the display 3a. The sequence program is displayed. Then, the user creates a program element D necessary for changing the control of the production system with respect to the read sequence program, and modifies the program element D to have a sequence number Sd.

  As shown in FIG. 3, the display 3a of the personal computer 3 is divided into two screens, and one screen is connected to the program elements B, C, E before change and their sequence numbers Sb, Sc, Se, and circuit connections. Lbc and Lce are displayed, and the changed program elements B, C, D, and E, their sequence numbers Sb, Sc, Sd, Se, and circuit connections Lbc, Lcd, and Lde are displayed on the other screen. Yes. That is, the sequence program is modified and changed from the sequence program displayed on one side of the display 3a to the sequence program displayed on the other side.

  When the modification of the sequence program is completed in this way, the user transfers the modified sequence program from the personal computer 3 to the PLC 1 and downloads it. Then, the PLC 1 executes the downloaded correction sequence program without stopping the production system.

  As described above, in the embodiment, the I / O module 7f is hot-plugged and this hot-plugged I / O is not necessary even when the production system is controlled by the PLC 1 while the sequence program is being executed. The control of the production system can be changed and executed by a sequence program partially modified corresponding to the module 7f. That is, in the embodiment, the PLC 1 can be constructed like a plug and play type.

FIG. 1 is a diagram showing a schematic configuration of a PLC and a personal computer which is a sequence program creation tool. FIG. 2 is a diagram showing a part of a sequence program of a block circuit diagram system. FIG. 3 is a diagram showing a display example of the display screen of the personal computer.

Explanation of symbols

1 PLC
3 Personal computer 5 CPU module 7a-7f I / O module

Claims (2)

  In a PLC construction method comprising one or a plurality of I / O modules and a CPU module that controls the input / output of signals in the I / O module according to a sequence program, the I / O module is activated during the execution of the sequence program. A step of line insertion / extraction, a step of causing the program tool to automatically recognize the I / O module that has been hot-inserted, a step of displaying a sequence program on the program tool screen, and a step of correcting the sequence program on the display screen; A PLC construction method comprising: a step of downloading correction data of a sequence program to the PLC side; and a step of rewriting the sequence program during RUN according to the downloaded correction data on the PLC side.   The sequence program is composed of a plurality of program elements obtained by blocking each input / output signal and internal operation function in units of individual I / O modules, and each program element is connected by a circuit with a sequence number. The PLC construction method according to claim 1, expressed in a circuit diagram manner.

Images