JPS62100805A - Programmable controller - Google Patents

Abstract

PURPOSE:To disable an outsider who knows no key word from reading a user program by permitting the reading of the user program only when the coincidence is obtained between an input keyword and a registered one. CONSTITUTION:The password data is supplied from a program console 7 with operation of a key and a collation key is pushed for collation at the side of a CPU 1 between the registered password data and the password data supplied by the operation of a key. If the coincidence is obtained between both data, a prescribed password coincidence flag is set at '1' and otherwise reset at '0' respectively. Under such conditions, the corresponding address of a user program is supplied with operation of a key. Thus the user program of the corresponding address is displayed on a display device of the console 7 as long as the password coincidence flag is set at '1'. While no user program is displayed if said coincidence flag is set at '0'. This prevents the surreptitious use of the user program.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a programmable controller having a function of preventing unauthorized theft of a user program.

(Summary of the Invention) The present invention includes an input means for inputting a keyword, a collation means for collating the input keyword with a registered keyword, and a device that permits reading of a user program from a user memory on the condition that the input keyword matches a registered keyword. The system is equipped with a permission means to prevent a third party who does not know the keyword from reading out the user program.

(Prior art and its problems) Recently, as programmable controllers have been incorporated into the control centers of various machines, user programs have come to include a considerable amount of know-how such as the operation sequence of the target machine. There is a growing desire to prevent such programs from being read by end users or competitors.

Conventionally, in order to meet these demands, a special key was given only to those authorized to handle programmable controllers, while a key-insertion type switch was installed on the controller body, making it impossible to operate this switch. Measures have been taken to allow reading of user programs only in certain cases.

However, this method has the problem that if the key itself distributed to the operator is stolen or lost, the key is of no use.

(Object of the Invention) An object of the present invention is to provide a programmable controller in which a user program cannot be read by anyone other than those who have been previously permitted to read the program.

(Structure and Effects of the Invention) In order to achieve the above object, the present invention includes an input means for inputting a keyword, a collation means for collating the input keyword with a registered keyword, and, on the condition of a collation match, The present invention is characterized by comprising a permission means for permitting reading of a user program from a user memory.

According to such a configuration, by not informing the keyword to anyone other than those who have been permitted to read the program in advance, the user program can be read only by a limited number of people, and unauthorized plagiarism of the user program can be prevented. can be reliably prevented.

(Description of Embodiments) FIG. 1 is a block diagram showing the overall hardware configuration of a programmable controller to which the present invention is applied.

In the figure, a CPU 1 is mainly composed of a microprocessor, and by executing various system programs stored in a system program memory 2, it performs various service functions in addition to its basic functions as a programmable controller. has been made possible.

The basic functions of a programmable controller include an input function that writes the input data taken in from the input converter 3 to the input canister of the input/output memory 4, and an input function that refers to the data of the input/output canister of the input/output memory 4. , an output update function that sequentially executes the user program stored in the user program memory 5 and rewrites the output data of the input/output memory 4 with the execution results, and the output data of the input/output memory 4 that has been rewritten as a result of instruction execution. This is an output update function that is sent from the output converter 6 to the outside.

Typical service functions include a program writing function that writes a user program input through key operations on the program console 7 to the user program memory 5, and a program writing function that writes the input/output data of the input/output memory 4 and the user program memory. Examples include a monitor function that displays the operating state of a designated circuit on the program console 7 with reference to the designated user program No. 5.

Note that the work memory 8 is used as a temporary storage area for various variable data when the above system program is executed.

Program console 7 is system bus 9 in this example.
It can be attached and detached freely from the CP.
This can be confirmed on the U1 side.

For example, the attachment/detachment status is determined by sensing, on the CPUI side, the conduction status of a connector that connects the program console 7 and the system bus 9.

As shown in FIG. 2, the front panel of the program console 7 includes a display 7a using a liquid crystal or the like.

A mode designation switch 7b and a keyboard 7C are provided for switching the operation mode to a run mode, a monitor mode, and a program mode.

This keyboard 7C has number keys from O to 9.

LD required by programmable controller instructions.

Command keys corresponding to OR, AND, OUT, etc., write,
Operation keys for giving commands such as reading and verification are provided respectively.

By using the display B7a and the keyboard 7C, it is possible to perform various interactions with the programmable controller.

Next, the process for registering a password in the programmable controller will be explained with reference to the flowchart in FIG.

When registering a password for the programmable controller, first connect the program console 7 to the system bus 9 (step 301). Then, the CPU
On the 1st side, the program console 7 is in a standby state ready to receive key data from the program console 7.

Next, enter the predetermined key for password registration into the key port 7.
The operation is performed at C (step 302).

Then, the CPU 1 side enters a state of waiting for processing for password registration.

In this state, key in the password data (step 303), and then operate the write key (step 3).
04). Then, the keyed-in password data is
It is written and registered at a predetermined address in a preset user program memory (step 305).

In this way, in a state where no password has been registered yet (for example, at the time of shipment), arbitrarily set password data can be registered at a predetermined address in the user program memory by performing a predetermined key operation for password registration. can do.

In particular, in this example, it is assumed that in a state where a password has not been registered yet, data oooo indicating unregistered is registered in the password registration area in the user program memory 5.

This registration may be performed, for example, at the time of shipment from the factory.

Next, details of the password verification process will be explained with reference to the flowchart shown in FIG.

Assume now that some password has already been registered in the programmable controller. In this state, when the program console 7 is connected to the system bus 9 (steps 401N, 402), a message requesting the password input is displayed on the display 7a of the program console 7 (step 401N, 402). 403).

In this state, enter the password data by performing a predetermined key operation on the keyboard 7C (step 4).
04), and when the collation key is operated again, step 405
), the CPU 1 side compares the registered password data with the keyed-in password data (step 4).
06).

Then, if a match is confirmed (step 40
7 (Yes), a predetermined password match flag is set to "1", whereas if no match is confirmed (Step 407: No), the password match flag is reset to 11011 (Step 409).

In this way, when the program console 7 is connected to the system bus 9 in a state where a password has already been registered, a message requesting a password is displayed on the display 7a of the program console 7. Only when the correct password is keyed in, the password match flag can be set to "1".

The state of this password match flag is automatically reset when the program console 7 is removed from the system bus 9 (step 402, negative) or the power is turned off (step 409).

Further, the state of the password match flag is automatically set to 111 II when the password registration is not yet completed, that is, when the password data is not oooo (No in step 401), without waiting for the match verification determination.

Therefore, as will be described later, anyone can read and write to the user program memory without registering a password.

Next, the details of the program reading and writing process performed on the condition that the passwords match will be explained with reference to the flowchart of FIG.

The password match flag explained in Figure 4 is set to "1'" once.
After it is set to "1", it continues to be set to "1" unless the program console is removed or the power is turned off.

In this state, when the corresponding address data of the user program is keyed in to read the user program (step 501), the password match flag is set to '1''.
only if set to (step 5024)
, the user program at the corresponding address is displayed on the display 7a (step 503).

On the other hand, if the password match flag is not set to "1pa" (No in step 502), the program at the corresponding address will not be displayed, but instead the buzzer built into the program console 7 will sound, allowing the user to Program plagiarism is prevented.

Further, if the password match flag is set to 411 tt (step 502 affirmative), after keying in the address data (step 501), keying in the command word (step 505), and operating the write key. Then (step 506), a user command is written to the corresponding address in the user program memory 5 (step 507).

On the other hand, similarly, this write process will not be performed if the password match flag is reset to "Out" (step 502, negative), and therefore there is a risk that the user program may be altered by careless write operations. It is also possible to prevent this from happening.

As described above, according to the embodiments shown in FIGS. 3 to 5, if anyone wants to freely read and write to the user program, there is no need to register any password data. On the other hand, if the user program includes the know-how of the target machine, it is sufficient to register an arbitrarily set password in advance using a predetermined key operation. Unless confirmed, read and write operations to the user program memory can be reliably prohibited.

Next, another embodiment of the present invention will be described with reference to FIGS. 6 to 8.

In this example, as shown in Figures 6 and 7, a password registration command is newly defined in the user command, and this password registration command is used in any step in the user program to write password data. I try to keep it that way.

That is, as shown in the command symbol diagram of FIG. 6, a password registration command FUNΔΔ is defined, and subsequently password data 1234 is written. In the user program, this is stored in steps (N+4) and (N+5), respectively, as shown in FIG.

When the user program is executed, this password registration command is processed in the same manner as a NOP command, so that it does not interfere with the circuit operation.

On the other hand, in order to rewrite this password registration command, it is necessary to memorize the corresponding steps in the user program, that is, steps (N+4) and (N+5). Therefore, even if the password data is stolen, the user program Number of registered steps in (N+4>, (N+5>
As long as the information is not known, it will be impossible to determine if there is a match, and further security against theft can be ensured.

FIG. 8 is a flowchart showing details of the password verification process in the cases of FIGS. 6 and 7.

In the same figure, when the program console 7 is connected to the system bus 9 after password data is registered using a password command (step 801 affirmative, 802 portrait), a password request message is displayed (step 80
3) is performed in the same manner as in the previous embodiment.

In this state, when the address data in which the password command is stored is keyed in (step 804), the password data is keyed in (step 806), and the verification key is operated (step 807) in sequence, the input step data and the password command are Only when a match with the stored step data is confirmed (step 8054)
(step 808), the password data is read, and then the registered password data and the keyed-in password data are further compared and verified (step 808).
Only if the two match (step 809N)
, the password match flag is set to 111 I+ (step 810).

On the other hand, if a match between the two is not confirmed (No in step 809), the password match flag is 0''.
will be reset to

Thus, in this embodiment, the program console 7
After inserting into the system bus 9, unless the storage step data of the password command is correctly keyed in in response to the password request command, the password match flag will be set to "'1" even if the password data is correct. Therefore, compared to the case of the first embodiment, it is possible to realize even more theft prevention performance.

In addition, in this embodiment, since the password command is written in the user program, the user memory is
When serially producing a plurality of devices that operate with the same program, the password data can be copied as well, and the trouble of registering a password for each programmable controller product can be omitted.

Furthermore, in the above embodiments, user program data is stored in a device other than the program console.

For example, printer interface, FROM writer, CR
By requiring each tool to set a password when transferring the program to a PC peripheral device such as a T device, it is possible to prevent the program from being printed out or displayed on a CRT screen.

In addition, although the password registration method described above is sufficient to protect the user program from being read or written by a third party, the operating procedure for password registration is made public to the PC purchaser, so it is possible for anyone other than the program creator to do so. It is also possible to register the password again.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall hardware configuration of a programmable controller to which the present invention is applied, FIG. 2 is a front view showing an example of a program console, FIG. 3 is a flowchart showing details of password registration processing, and FIG. 4
The figure is a flowchart showing details of the password verification process.
Figure 5 is a flowchart showing details of program reading and writing processing, Figure 6 is an explanatory diagram showing the layout of password registration commands on a ladder diagram in another embodiment, and Figure 7 is a flowchart showing details of program reading and writing processing.
The figure is a memory map showing the storage step of the password registration command in the user program in Haku's embodiment, and FIG. 8 is a flowchart showing details of the password verification process in another embodiment. 1... CPU 2... System program memory 3... Input converter 4... Input/output memory 5... User program memory 6... Output converter 7... Program console 8... Work Memory 9...System bus 7a...Display 7b...Mode designation switch 7C...Keyboard Figure 1 Figure 2

Claims (1)

[Claims] (1) It is equipped with an input means for inputting a keyword, a collation means for collating the input keyword with a registered keyword, and a permission means for permitting reading of the user program from the user memory on the condition that the input keyword matches the registered keyword. A programmable controller characterized by: