JP2001229015A - Controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a conventional controller is constituted so that only the rewrite of a program can be operated, and that the rewrite of intrinsic variable of the program can not be operated. SOLUTION: An already edited program and local variables to be used only by the program are inputted from an engineering device 9 to a receiving part 21, and a program stored in a program area 11 and local variables stored in a local variable storage area 12 are rewritten into the received program and local variables by a program rewriting part 20 based on program page use information 13 for storing a page in which the program is allocated to the program area 11 and local variable page use information 14 for storing a page in which the local variables are allocated to the local variable area 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for executing a program for controlling an industrial plant, and more particularly to a change of a program during operation.

[0002]

2. Description of the Related Art FIG.
FIG. 7 is a block diagram showing a control device having a function of supporting a conventional program change during operation disclosed in Japanese Patent Publication No. In FIG. 22, reference numeral 1 denotes an engineering device for editing a program, and a support tool 2 for editing the program.
And a display unit 3. 4 is engineering equipment 1
This is a control device that executes the program edited in the above, and has a control unit 5 that executes the program and a memory 6 that stores the program to be executed.

Next, the operation will be described. FIG.
FIG. 2 is a diagram illustrating a control device having a function of supporting a conventional program change during operation disclosed in Japanese Patent Application Laid-Open No. 9-244717. In FIG. 23, A, B, and C are structural units of a program in the memory 6, and BB is a program after B is changed. Before the change, the programs A, B, and C are stored in the memory 6. When changing B to BB, BB is first downloaded from the engineering apparatus 1 to the memory 6. Next, a JUMP Y instruction is inserted into the △△ part of BB, and finally a JUMP X instruction is inserted into the ** part of B. While writing BB to the memory 6, the program B before the change is executed. When the writing of B 'is completed and the JUMP Y instruction is inserted into the △△ portion of BB, the changed program BB can be executed. Therefore, the JUMPX instruction is inserted into the ** portion of B. , So that the changed program BB can be executed. With the above procedure, it is possible to change the running program.

[0004]

In the conventional control device constructed as described above, when the rewriting of the program is repeated, the used area on the memory 6 becomes fragmented, which is not preferable in itself. I quoted this as an example that specializes only in changing the program. Thus, the change process is completed only by changing the program,
This means that the data handled by the program is a global variable that can be referenced by a plurality of programs. This is a case where only the relevant program is handled, and there is no local variable that is a variable that cannot be referenced from other programs.

A program that handles only such global variables is inconvenient to use in an engineering apparatus. Local variables have the effect of increasing the independence of each program, and are distinguished from global variables.
If multiple programs can access the same variable,
There is a problem that which program has rewritten which variable, and it takes time for debugging.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and provides a control device capable of changing a program during operation even in a program written in a programming language that handles local variables. That is the primary purpose. It is a second object of the present invention to provide a control device that can cope with a case where address modification is performed on a local variable or a case where a data width is different.

It is a third object of the present invention to provide a control device capable of continuously using the values of local variables used by the program before the change. It is a fourth object of the present invention to provide a control device that can use a program created in a conventional programming language that does not handle local variables and a program created in a programming language that handles local variables in a mixed manner.

[0008]

In the control device according to the present invention, a program area for storing a program, a local variable area for storing a local variable used only by the program, and a page in which the program is allocated to the program area. , A local variable page usage information section in which a page in which local variables are allocated to the local variable area is stored, a program input from an engineering device for editing the program, and only this program A receiving unit that receives a local variable to be used, and a rewriting unit that rewrites the program area by a program received by the receiving unit and rewrites the local variable area by the local variable received by the receiving unit. Things.

In addition, a local variable page management information section referred to when a logical address of a local variable described in the program is changed to a physical address is provided, and the rewriting section is adapted to rewrite the local variable page in accordance with the rewriting of the local variable. It rewrites the management information section. Also, the validity of the logical address of the local variable is checked by using the local variable word number information section for storing the number of words of the local variable transferred from the engineering device and the local variable word number information section when executing the program. It has an unauthorized address detection unit.

Furthermore, the rewriting section rewrites the local variable area so that the value of the local variable before rewriting is inherited.

A program described in a first language which is a program used in the control device;
An identification unit that identifies a program described by a second language different from the first language, and a second local variable area that stores a local variable in the program described by the second language, The rewriting unit does not rewrite the local variable stored in the second local variable area for the program identified as the second language by the identification unit.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing Embodiment 1 of the present invention. In FIG. 1, reference numeral 8 denotes a control device that implements a control program. 9
Is an engineering device used for creating a program to be executed by the control device 8 and monitoring variables of the control device 8.

The control device 8 is configured as follows. A program / local variable area 10 stores a program and variables used only by the program. A program area 11 stores a program, a local variable area 12 stores a local variable, and a program used to allocate a program storage area.・ Page usage information 1
3 and local variable / page usage information 14 used for allocating a storage area for local variables. Reference numeral 15 denotes a program execution control unit that controls the execution of the program. The program / page management information 16 manages which page each program is assigned to, and the page to which the local variables used by each program are assigned. Variable / page management information 17 for managing
And an instruction execution unit 18 that reads a program from the program area 11 and executes the program under the control of the program execution control unit 15. Reference numeral 19 denotes an engineering device request processing unit that processes a request from the engineering device 9, a program rewriting unit 20 that rewrites a program, a receiving unit 21 that receives data from the engineering device 9, and transmits data to the engineering device 9. It has a transmission unit 22.

FIG. 2 is a diagram for explaining the role of the local variable / page usage information 14 of the control device shown in FIG. In FIG. 2, the local variable / page usage information is expressed as a set of bits having a value of 1 or 0. Each bit is associated with each page of the local variable area 12 sequentially from the least significant bit of the lower address. Here, the page of the local variable has a fixed number of words (1 word is 1 word).
6 bits), which is a unit for allocating local variables. As shown in FIG. 2, the page of the local variable in which the value of the bit of the local variable / page usage information 14 is 1 indicates that the page has been allocated, that is, is in use. The program rewriting unit 20 can recognize the free area of the local variable area 12 by searching the local variable / page usage information 14. To secure a free area, 1 is written to the corresponding bit. In FIG. 2, the relationship between the local variable / page usage information 14 and the local variable area 12 has been described, but the relationship between the program page usage information 13 and the program area 11 is also the same.

FIG. 3 is a diagram for explaining the role of the local variable / page management information 17 of the control device shown in FIG. In FIG. 3, a module means a program execution unit (and therefore also a rewrite unit). The local variable / page management information 17 is for storing pages of the local variable area 12 used by each module. In FIG. 3, module 0 has pages 2, 3, 7
Shows that the module 2 uses pages 8 and 9. When the value of the local variable / page management information 17 is FF (hexadecimal number), it indicates that the page is not used any more. The values of the local variable / page management information 17 of the module 1 are all FF. This is the case when the module 1 is not defined, or in a very rare case, the module 1 completely stores the local variable area 12. Indicates that it is not used. In FIG. 3, the relationship between the local variable / page management information 17 and the local variable area 12 has been described.
The same applies to the relationship between the program areas 11.

FIG. 4 is a diagram for explaining the conversion from a logical address to a physical address using the local variable / page management information 17 of the control device shown in FIG. Here, the logical address is used to designate a variable and is written in an actual program. On the other hand, the physical address indicates the address of an actual variable on the memory. For example, even if the logical address is the same, the physical address is different if the module is different.

As shown in FIG. 4, the logical address is
It consists of a logical page number and an offset within the page. The intra-page offset is common to the logical address and the physical address. By combining the logical page number and the module number, an offset from the base address of the local variable / page management information 17 described with reference to FIG. 3 can be calculated. The value of the local variable / page management information 17 corresponding to this offset is the page number to be accessed. The physical address is composed of the page number read in the above procedure and the offset within the page. The conversion of the local variable from the logical address to the physical address in FIG. 4 is performed by the instruction execution unit 18 when the local variable needs to be accessed. FIG. 4 illustrates the conversion of a logical address from a physical address to a physical address in a local variable, but the same applies to the conversion of a logical address into a physical address in a program.

FIG. 5 is a diagram showing a transfer format of data transferred from the engineering device to the control device according to the first embodiment of the present invention. The transfer data of FIG. 5 includes a module number indicating the uniqueness of a module which is an execution unit of the program, the number of words of the transferred program, the number of words of the transferred local variable, the contents of the program, and the contents of the local variable. It is.

FIG. 6 is a flowchart illustrating the operation of the control device according to the first embodiment of the present invention. FIG.
FIG. 4 is a diagram for explaining an operation result of the control device according to the first embodiment of the present invention. FIG. 8 shows Embodiment 1 of the present invention.
FIG. 6 is a diagram for explaining the effect of the control device according to FIG.

Next, the operation will be described with reference to FIG. When the receiving section 21 of FIG. 1 receives the transfer data shown in FIG. 5, the program rewriting section 20 of FIG. 1 operates.
The flowchart of FIG. 6 shows the operation of the program rewriting unit 20 at this time. Program rewriting unit 20
Calculates the required area from the number of program words and the number of local variable words of the transfer data, searches the program page usage information 13 and the local variable / page usage information 14, and checks whether there is an empty area. (S1
-1). If there is no free area, the abnormal end is notified to the engineering apparatus 9 and the processing is terminated (S1-1).
1). If there is a free area, the area is acquired (S1-
2) Copy the contents of the program of the transfer data to the area acquired for the program (S1-3). Next, the contents of the local variables of the transfer data are copied to the area obtained for the local variables (S1-4).

Next, the execution state of the module to be rewritten is checked (S1-5). If the target module is running, wait until the execution is completed. In the flowchart, when the module state is being executed, the description indicates that an in-loop occurs. However, in practice, a CPU time is allocated to each of a task for executing a program and a task of the program rewriting unit 20. So there is no in-loop. If the module is not being executed or the module being executed is completed, the module state is changed to rewriting (S1-6), and the program area 11 and the local variable area 12 used by the module before the change are released. (S1-7). Here, the process of releasing an area is a process of obtaining a page number with reference to the page management information of a target module, and setting a bit of the corresponding page use information to 0 (returning it to unused). Each is performed on a local variable.

Next, the execution management information of the module is changed (S1-8). A process of writing the page number of the secured area into the page management information is performed. Next, the state of the module that is being rewritten is changed to executable (S1-9).
This completes the rewriting. Finally, the normal end is transmitted to the engineering apparatus 9 (S1-10), and the process is ended.

FIG. 7 is a diagram for explaining how the program area 11 and the local variable area 12 are changed by the operation described above. In FIG. 7, the module to be rewritten is module 0, and uses page 0 and page 1 of the program area 11 and page 0 of the local variable area 12 before rewriting. The program corresponding to the module 0 is changed, and the program area 11 is changed.
When three pages are required and two pages are required as the local variable area 12, the transfer data is downloaded to the control device 8 according to the format. In the control device 8, FIG.
The rewriting process is performed based on the flowchart of FIG. After rewriting, the module 0 stores page 5 of the program area 11.
And pages 6 and 9 and pages 1 and 7 of the local variable area 12 are used, and the areas used before rewriting are released.

FIG. 8 is a diagram for explaining the effect of the first embodiment of the present invention. In the first embodiment, by rewriting the local variables in the program rewriting unit 20, each module can handle a local variable uniquely accessed, and a highly independent module (program) can be executed by the control device. Is now possible. In the conventional example, only variables that can be commonly accessed by each module are prepared, so even if a program is created with the intention of module-specific variables, other modules will access it and unexpected behavior will occur there is a possibility. On the other hand, in the control device 8 including the program rewriting unit 20 according to the first embodiment, other modules cannot access local variables unique to the module. The high independence of the program is specifically as described above, and there is an effect that the program productivity can be improved by reducing the time required for debugging.

Further, even if the logical address is the same, the local variable is mapped to a different physical address if the module is different, so that there is an effect that the diversion by copying the program is improved and the program productivity is improved. . Further, in the conventional example, it was necessary to initialize the variables by a program. However, in the first embodiment, the initialized values of the local variables can be transferred from the engineering device 9. There is no need to create it, and productivity can be improved.

Embodiment 2 FIG. FIG. 9 is a block diagram showing a control device according to a second embodiment of the present invention. Compared with the block diagram shown in FIG. 1, an illegal address detection unit and local variable / word number information are added. 9, 8 to 22 are the same as those in FIG.
Reference numeral 23 denotes an illegal address detection unit that checks the validity of a logical address of a variable accessed when executing an instruction. Reference numeral 24 denotes local variable / word number information.
3, and holds the value of the number of words of the local variable shown in FIG. 5 for each module. The process of copying the value from the transfer data of FIG. 5 to the local variable / word number information 24
Can be carried out in S1-8 of the flowchart of FIG.

FIG. 10 is a diagram for explaining address modification of the control device according to the second embodiment of the present invention. FIG. 10 shows that the logical address of the local variable is the sum of the logical address written in the program and the modifier. If the qualifying element is not appropriate, the logical address after the qualification may be incorrect, so a check is required. FIG. 11 is a flowchart illustrating an operation of the control device according to the second embodiment of the present invention.

Next, the operation will be described with reference to FIG. FIG. 11 shows a process performed by the illegal address detection unit 23 when the instruction execution unit 18 needs to access a local variable. First, it is checked whether address modification is performed (S2-1). When performing address modification, a qualified logical address is calculated (S
2-2). If you do not do address qualification, do nothing,
Move to S2-3. Next, the value of the logical address is copied to a comparison variable (S2-3). Here, the comparison variable is a variable for comparison with the local variable / word number information 24. Next, the data width of the local variable to be accessed is checked (S2-4). Here, 16 bits, 32 bits,
It is assumed that a data width of 64 bits is handled. If the data width is 16 bits (one word), nothing is performed, and S2-
Move to 7. If the data width is 32 bits, it becomes 2 words, so 1 is added to the comparison variable (S2-5). If the data width is 64 bits, the data length is 4 words, so 3 is added to the comparison variable (S2-6). Next, the comparison variable is compared with the word number of the corresponding module stored in the local variable / word number information 24 (S2-7). Here, it is checked that the logical address is not a negative number and that the comparison variable is not more than the number of words of the corresponding module stored in the local variable / word number information 24. If it is invalid, the detection of the illegal address is recorded (S2-10), and the process is terminated. If normal,
The logical address is converted to the physical address (S2-8),
The local variable is accessed (S2-9), and the process ends.

Next, the effect of the second embodiment will be described. The address modification as shown in FIG. 10 is used for accessing an array variable. In the base logical address,
Accessing array variables starting from the base logical address by repeating the operations of adding a qualifier, accessing a variable, incrementing a qualifier, adding a qualifier to a logical address, and accessing a variable can do.

The provision of the illegal address detection section 23 in the control device 8 has an effect that array variables can be handled while maintaining the framework of module-specific local variables. Also, the unauthorized address detection unit 23
Since a check mechanism according to the data width is provided, the present invention can be applied even when the data width is different.

Embodiment 3 FIG. 12 is a block diagram showing a control device according to Embodiment 3 of the present invention. FIG.
Compared with the block diagram shown in FIG. 7, a local variable / takeover table and local variable / takeover page management information are added. 12, 8 to 24 are the same as those in FIG. 25 is a program execution control unit 1
5 is a local variable / takeover table provided in the program execution control unit 15.
It is takeover page management information.

FIG. 13 is a diagram showing a format of data transferred from the engineering device to the control device according to the third embodiment of the present invention. In FIG. 13, the module number, the number of words of the program, and the contents of the program are as described in the transfer data format of FIG. The format shown in FIG. 13 is intended to make it possible for the program after the change to continuously use the values of all or some local variables used by the module before the change. Further, the changed program can add a new local variable.

FIG. 14 shows a state in which the changed local variables of the control device according to the third embodiment of the present invention are constituted by a part (or all) of the local variables before the change and the added local variables. FIG. Returning to FIG.
The number of words of the local variable after change is the total number of words of a part (or all) of the local variable before change and the number of words of the added local variable. The word number of the local variable before the change is the word number of the local variable used by the module before the change. The word number of the added local variable is the word number of the local variable added this time. The contents of the additional local variables are included in the transfer data. The copy source bit string and the copy destination bit string
It is used to configure local variables after modification as described below.

FIG. 15 is a diagram illustrating a copy source bit string and a copy destination bit string of the control device according to the third embodiment of the present invention. In FIG. 15, each bit of the copy source bit string corresponds to each logical address of the local variable before change. If the value of the bit is 1, it indicates that the variable should be inherited by the changed local variable. If the value is 0,
The variable is discarded. Each bit of the copy destination bit string corresponds to each logical address of the changed local variable.
A bit value of 1 indicates that the copy source is an additional local variable, and a value of 0 indicates that the copy source is a local variable before change.

FIG. 16 is a diagram for explaining the local variable / takeover table 25 of FIG. In FIG. 16, the local variable / takeover table 25 is created based on the above-described copy source bit string and copy destination bit string. The logical address of the local variable before the change is taken as an offset, and the contents are the logical address of the local variable after the change and the inherited bits. If the takeover bit is 1, it indicates that the contents of the pre-change local variable logical address are to be taken over by the post-change local variable, and the post-change local variable logical address specifies its destination. A value of 0 indicates that the pre-change local variable logical address is discarded (in this case, the destination is invalid).

FIG. 17 is a view for explaining the local variable / takeover page management information 26 of FIG. The format in FIG. 17 is the local variable / page management information 17
Is the same as The local variable / takeover page management information 26 includes the changed local variable / page management information 17.
Has the same content as FIG. 18 shows Embodiment 3 of the present invention.
Is a flowchart showing the operation of the program rewriting unit of the control device according to the first embodiment. FIG. 19 is a flowchart showing the operation of the program execution control unit of the control device according to Embodiment 3 of the present invention.

Next, the operation will be described with reference to FIG. Embodiment 3 is realized by the cooperative operation of the program rewriting unit 20 and the program execution control unit 15. Compared to the flowchart of FIG. 6, the processing of S3A-1, S3A-2, and S3A-3 is performed instead of the processing of S1-4. Further, the process of S3A-4 is added. S1
The processes from -1 to S1-11 (except for S1-4) are the same as those in the first embodiment, and a description thereof will be omitted.

In S3A-1, an additional local variable is copied to the obtained area. Each local variable of the transfer data is copied in order from the one at the lower logical address.
The copy destination is determined by the copy destination bit string of the transfer data. If the value of the copy destination bit string is 1, the additional local variable is copied. In S3A-2, the changing flag is turned ON. The changing flag is set in the program execution control unit 1
5 references.

In S3A-3, the local variables before change are copied to the acquired area. The logical address of the copy source is obtained from the copy source bit string whose value is 1.
For the logical address of the copy destination, the value of the copy destination bit string is 0.
Find from what is. Processing is performed in order from the lower logical address of the local variable before change. In parallel with this processing, the local variable / takeover table 25 of FIG. 12 is created. For those that need to be inherited, the inherited bit is set to 1 and the logical address of the local variable is written after the change. For those that do not need takeover, the takeover bit is set to 0. Since the takeover bit is initialized to 0, the takeover bit remains at 0 if the copy has not been completed. In S3A-4, the changing flag is turned off.
In this way, while rewriting the local variables,
The local variable / takeover table 25 is created.

Next, the operation of the program execution control unit 15 will be described with reference to FIG. Program rewriting and program execution are time-divided in CPU processing. FIG.
Is a process when a store instruction to a local variable occurs. In FIG. 19, it is checked whether the changing flag is ON (S3B-1). When the changing flag is OFF, a normal store instruction is processed (S3B-
7), end the processing. When the changing flag is ON,
It is checked whether the module currently being executed is a module being rewritten (S3B-2). If the module being executed is not the module being rewritten, a normal store instruction process is performed (S3B-7), and the process ends.

If the module being executed is a module being rewritten, it is written to the pre-change local variable logical address (S3B-3). In this case, access is performed using the local variable / page management information 17 of the corresponding module. Next, the value of the takeover bit is checked with reference to the local variable / takeover table 25 (S3B-4).
3B-5). If the value of the takeover bit is 0, the change is not reflected in the local variable, and the process ends. If the value of the takeover bit is 1, the data is written to the changed local variable logical address (S3B-6). In this case, access is performed using the local variable / takeover page management information 26.

Next, the effect of the third embodiment will be described. The third embodiment has an effect that the values of the local variables before the program change can be continuously used after the program change. For example, in the timer instruction used in the control program, the value being counted is held in the local variable, so that the value counted before the change can be continuously used after the change. Since local variables can be added, the program and local variables before the change can be used as they are, and only the newly needed parts of the program and local variables can be added.

Embodiment 4 FIG. FIG. 20 is a diagram for explaining local variable / page usage information when the control device according to the fourth embodiment of the present invention is mixed with a conventional program. In the description of the local variable / page usage information shown in FIG. 2, a conventional program (a program in a second language)
20 does not deal with the local variable area of FIG.
By changing the meaning of the area pointed to by the local variable / page usage information as shown in (1), a local variable area (second local variable area) for a conventional program can be provided. Further, an identification unit for identifying a conventional program from the program of the present invention (program in the first language) is provided. FIG. 21 is a flowchart showing the operation of the program rewriting section of the control device according to Embodiment 4 of the present invention.

Next, the operation will be described with reference to FIG. In FIG. 21, first, the identification unit checks whether the program is a conventional language program (S4-1). In the case of a conventional language program, since local variable assignment processing is unnecessary, only program rewriting processing is performed (S
4-4), the process ends. If the language is not the conventional language, as described in the first embodiment, the program rewriting process (S4-2) and the local variable rewriting process (S4-3)
Is performed, and the process ends.

Next, effects of the fourth embodiment will be described. Since the local variable / page usage information 14 excludes the area of the local variable of the program written in the conventional language, there is an effect that it can coexist with the program in the conventional language. For example, if a part written in a conventional language is used as it is and new functions are added,
You can write programs in languages that handle local variables.

[0046]

Since the present invention is configured as described above, it has the following effects. A program area for storing the program, a local variable area for storing local variables used only by the program, a program page usage information section for storing pages allocated to the program area in the program, and a local variable for the local variable area. A local variable page use information section in which the allocated pages are stored, a program input from an engineering device for editing the program and a receiving section for receiving a local variable used only by the program, and a receiving section for receiving the program. Since the program area is rewritten by the program and the local variable area is rewritten by the local variable received by the receiving section, the rewriting section is provided, so that the program and the local variables can be rewritten during the operation of the program. .

The local variable page management information section referred to when a logical address of a local variable described in a program is changed to a physical address is provided. Since the management information section is rewritten, the physical address of the local variable can be accessed during the execution of the rewritten program. Also, the validity of the logical address of the local variable is checked by using the local variable word number information section for storing the number of words of the local variable transferred from the engineering device and the local variable word number information section when executing the program. With the provision of the illegal address detection unit, the validity of the logical address of the local variable can be checked.

Further, since the rewriting unit rewrites the local variable area so that the value of the local variable before rewriting is inherited, the variable value before rewriting can be used after rewriting.

A program described in a first language, which is a program used in the control device,
An identification unit that identifies a program described by a second language different from the first language, and a second local variable area that stores a local variable in the program described by the second language, The rewriting unit does not rewrite the local variable stored in the second local variable area for the program identified by the identification unit as being in the second language, so that programs in different languages are mixed. Good.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating local variable / page usage information of the control device shown in FIG.

FIG. 3 is a diagram for explaining local variable / page management information of the control device shown in FIG. 1;

FIG. 4 is a view for explaining conversion from a logical address to a physical address using local variable / page management information of the control device shown in FIG. 1;

FIG. 5 is a diagram showing a format of transfer data transferred from the engineering device to the control device according to the first embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation of the control device according to the first embodiment of the present invention.

FIG. 7 is a diagram illustrating an operation result of the control device according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating the effect of the control device according to the first embodiment of the present invention.

FIG. 9 is a block diagram showing a control device according to a second embodiment of the present invention.

FIG. 10 is a diagram illustrating modification of an address of a control device according to a second embodiment of the present invention.

FIG. 11 is a flowchart illustrating an operation of the control device according to the second embodiment of the present invention.

FIG. 12 is a block diagram showing a control device according to a third embodiment of the present invention.

FIG. 13 is a diagram showing a format of transfer data transferred from an engineering device to a control device according to a third embodiment of the present invention.

FIG. 14 is a diagram illustrating a configuration of a changed local variable of a control device according to a third embodiment of the present invention.

FIG. 15 is a diagram illustrating a copy source bit string and a copy destination bit string of the control device according to the third embodiment of the present invention.

FIG. 16 is a diagram illustrating a local variable / takeover table of a control device according to a third embodiment of the present invention.

FIG. 17 is a diagram illustrating local variable / takeover page management information of the control device according to the third embodiment of the present invention.

FIG. 18 is a flowchart showing an operation of a program rewriting unit of the control device according to Embodiment 3 of the present invention.

FIG. 19 is a flowchart showing an operation of a program execution control unit of the control device according to the third embodiment of the present invention.

FIG. 20 is a diagram for explaining local variable / page usage information in the case where the control device according to the fourth embodiment of the present invention is mixed with a conventional program.

FIG. 21 is a flowchart illustrating an operation of the control device according to the fourth embodiment of the present invention.

FIG. 22 is a block diagram showing a conventional control device.

FIG. 23 is a diagram illustrating a conventional control device.

[Explanation of symbols]

8 control device, 9 engineering device, 10 program / local variable area, 11 program area, 1
2 Local variable area, 13 Program page usage information, 14 Local variable / page usage information, 15 Program execution control unit, 16 Program page management information, 17 Local variable / page management information, 18 Instruction execution unit, 19 Engineering equipment request Processing unit, 20
Program rewriting unit, 21 receiving unit, 22 transmitting unit,
23 illegal address detection unit, 24 local variable / word number information, 25 local variable / takeover table, 26
Local variable / takeover page management information.

Claims (5)

[Claims] In a control device configured to control a controlled device by executing a program and to change a program in operation, a program area for storing a program and a local variable used only by the program are stored. A local variable area, a program page use information section storing a page in which the program is allocated to the program area, a local variable page use information section storing a page in which the local variable is allocated to the local variable area, A receiving unit that receives a program input from an engineering device that edits a program and a local variable used only by the program, rewrites the program area by the program received by the receiving unit, and receives the program by the receiving unit. Local variables A rewriting unit for rewriting the local variable area. 2. A local variable page management information section referred to when a logical address of a local variable described in a program is changed to a physical address, wherein the rewriting section is adapted to rewrite the local variable in accordance with the rewriting of the local variable. 2. The page management information section is rewritten.
The control device as described. 3. A local variable word number information section for storing the number of words of a local variable transferred from an engineering apparatus. When executing a program, the local variable word number information section is used to validate a logical address of a local variable. The control device according to claim 1, further comprising an unauthorized address detection unit that checks the address. 4. The control device according to claim 1, wherein the rewriting unit rewrites the local variable area so that the value of the local variable before the rewriting is inherited. 5. A program described in a first language that is a program used in the control device according to claim 1, and a second language different from the first language. An identification unit for identifying a program described by the second language, a second local variable area for storing a local variable in the program described by the second language, the rewriting unit, the second language by the identification unit The control device according to claim 1, wherein the local variable stored in the second local variable area is not rewritten for the program identified as.