JPH1011325A - Programmable controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily detect a software run away and speedily take measures against trouble after disconnecting a faulty system immediately. SOLUTION: A sequence engine 22 always judges whether or not trouble occurs on a handshake basis. The sequence engine 22 if detecting trouble inhibits an MPU 1 from accessing an I/O memory 5 by using a bus controller 21. Then the sequence engine 22 judges whether or not write address is needed to stops software PLC itself and ends the process when the write access is not necessary, and further judges whether or not I/O update is needed when the write access is necessary. The sequence engine 22 when judging the I/O update is necessary updates the I/O memory 5. When it is judged that the I/O update is not necessary, on the other hand, the software PLC itself is stopped and the process is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a programmable controller, and more particularly, to a programmable controller for controlling an external device using a personal computer operated under the control of a general-purpose OS.

[0002]

2. Description of the Related Art A dedicated programmable controller is used to control an external device. In recent years, a programmable controller using a general-purpose personal computer has been used.
That is, a soft programmable controller (hereinafter, referred to as a soft PLC) has begun to be used.

This software PLC is used not only when a personal computer is used in a stand-alone type but also in a network type. In addition, a general-purpose OS (Operating System) used in a conventional personal computer, for example, WINDOWS
The external device is controlled under the management of.

[0004]

However, in such a conventional soft PLC, as described above, a general-purpose OPC is used.
Since S is used, the reliability is lower than that of a dedicated OS used for a normal PLC, and there is a possibility that software runaway may occur.

[0005] Once software runaway occurs, external devices cannot be controlled for scanning within a predetermined period of time, causing not only malfunction of the external devices but also hang-up of the entire system.

[0006] As described above, when software runaway occurs, it has a very serious effect on external devices,
In a conventional soft PLC used under a general-purpose OS, there is a problem that failure detection due to software runaway, disconnection of a failure system, and failure countermeasures are not performed promptly.

For example, in a stand-alone type soft PLC, it is impossible to detect even a fault due to a software runaway, and in a network type soft PLC, only a fault can be detected. Failure measures are not taken promptly.

In view of the above-mentioned problems, the present invention quickly detects a software runaway in a software PLC operating under the control of a general-purpose OS, immediately disconnects a faulty system, and quickly takes countermeasures against the fault. It is an object of the present invention to provide a programmable controller that performs the operation.

[0009]

According to one aspect of the present invention, there is provided a programmable controller for controlling an external device using a personal computer operated under the control of a general-purpose OS. Has an expansion board, the expansion board has runaway detection means for detecting software runaway, and I / O protection means for disconnecting a predetermined external device when the runaway detection means detects software runaway transmission. The I / O protection means includes an I / O updating means for causing an external device to execute a preset process when a predetermined external device is disconnected.

According to a second aspect of the present invention, in the first aspect of the present invention, the runaway detecting means includes code storage means for storing a predetermined code at predetermined time intervals by an MPU provided in the personal computer; And a timer for measuring time. The timer reads a code stored in the code storage means each time a predetermined time elapses, and the read code is not a predetermined code stored by the MPU. In this case, the software determines that runaway has occurred, while if the read code is the predetermined code stored by the MPU, the software determines that runaway has not occurred, and Is cleared.

According to a third aspect of the present invention, in the first aspect of the present invention, when the software runaway is detected by the runaway detection means, the I / O protection means transmits the MPU provided in the personal computer to the MPU. On the other hand, access to an I / O memory in which data indicating the operation of an external device is stored is prohibited.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the I / O updating means has fail-safe data storage means for storing fail-safe data when software runaway is detected. After rewriting the fail-safe data stored in the fail-safe data storage means to an I / O memory storing data indicating the operation of the external device, the I / O memory is rewritten to the MPU. The feature is that access to the memory is permitted.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the expansion board has a sequence engine.

According to the present invention, when the expansion board mounted on the personal computer detects a software runaway, a predetermined external device is disconnected, thereby preventing the malfunction of the external device due to the software runaway.

Then, when a predetermined external device is disconnected,
Since the external device executes the preset processing, the external device system does not stop.

In particular, every time the timer elapses a predetermined time,
The code stored in the memory is read, and if the read code is not the predetermined code stored by the MPU, it is determined that the software is out of control.
If the read code is a predetermined code stored by the MPU, the software determines that no runaway has occurred.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a soft PLC according to the present invention will be described.
Will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a soft PLC according to the present invention.

The soft PLC according to this embodiment includes an MPU
1, an expansion board having a fail-safe function and a ladder accelerator function described later 2, a system program memory (SM) storing a general-purpose OS, and a user storing a ladder program (sequence program) for controlling an external device system. Program memory (U
M) 4, an external device, for example, an I / O memory 5 for storing data for activating a counter or a timer, and an input / output circuit 6 for transferring the data of the external device to and from the system bus. 10 are connected.

The expansion board 2 detects a software runaway (failure detection) by using the MPU 1 and a handshake method described later, disconnects a predetermined external device on the system from the system (I / O protection), and then performs I / O protection. The memory 5 is refreshed. The bus controller 21, the sequence engine 22, the user memory 23 for storing a sequence program for processing the fail-safe function and the ladder accelerator function, and the external device disconnected after detecting a software runaway A data memory (DM) 24 for storing fail-safe data for restoring the device, a timer 25 for measuring time, and a handshake memory (H
M) 26.

The bus controller 21 includes a system bus 1
0 to control the use of the bus 10, and when software runaway is detected, the right to use the bus 10 is
1 and the extension board 2 holds it.

The sequence engine 22 processes a fail-safe function and a ladder accelerator function. Here, the ladder accelerator function means MP
This is a function for processing a part or all of the processing executed by U1 at high speed. Since this function has no direct relation to the present invention, further description is omitted.

The handshake memory 26 is used in a handshake process which will be described later.
The extension board 2 itself stores predetermined codes at predetermined intervals.

Here, a method of detecting a software runaway by the handshaking method of the soft PLC of this embodiment will be described with reference to FIG.

As shown in the figure, the MPU 1 operates for a predetermined time t.
The predetermined contents A are written into the handshake memory 26 on the extension board 2 at one interval (see and in the figure).

Thereafter, the sequence engine 22 checks the contents stored in the handshake memory 24 when the timer 25 elapses a predetermined time t2 (t1 ≦ t2).

If the data stored in the handshake memory 26 is A (see the figure), the sequence engine 22 determines that the software has been executed normally, and Is rewritten to 0 (and in the figure).

On the other hand, when the value stored in the handshake memory 26 is 0 (see FIG. 3), the sequence engine 22 does not execute the scan of the sequence program as predetermined, and software runaway occurs. Judge that you have done.

Next, a method for disconnecting an external device from the system by the soft PLC of this embodiment will be described.

As described above, when the runaway of the software is detected by the handshake method, the sequence engine 22 issues an instruction to the bus controller 21 to deprive the MPU 1 of the right to use the line of the bus 10 and sends the instruction to the expansion board 2. Get the right to use the line.

The sequence engine 22 is an extension board 2
Obtains the line use right, the MPU 1 prohibits the access to the I / O memory 5 in order to disconnect a predetermined external device based on the sequence program stored in the user memory 23 in advance.

The MPU 1 uses the data stored in the I / O memory 5 to prohibit, for example, a statistical process or the like, from prohibiting write access to the I / O memory 5 and performing only read access. May be performed.

When it is necessary for the system administrator to strictly manage data when performing write access to data, the write command is complicated, that is, a complicated write procedure is provided, and the write command is complicated. May be prohibited.

Here, access control is performed by the I / O memory 5.
A register may be provided in the bus interface circuit of the above, and the interface circuit may be controlled by setting the register.

Next, read / write access to the I / O memory 5 of the MPU 1 after the soft PLC of this embodiment disconnects an external device will be described in a DM write format and a ladder execution format.

In the case of DM writing format When the sequence engine 22 prohibits the access to the I / O memory 5 of the MPU 1 by using the bus controller 21 roller, the sequence engine 22 converts the fail-safe data stored in the data memory 24 into I / O Rewrite and update in the memory 5.

For example, when a predetermined external device is an input device and the operation of this device is stopped, the corresponding data in the I / O memory 5 is changed. More specifically, the opening / closing data of the contact (a contact or b contact) may be changed so as not to be input to the input device.

Thereafter, the sequence engine 22 instructs the bus controller 21 to pass the right to use the bus 10 from the expansion board 2 to the MPU 1.

Then, the MPU 1 resumes control of the external device based on the sequence program stored in the user program memory 24 and the data stored in the I / O memory 5 again.

In the case of the ladder execution format In this case, the sequence engine 22 has an accelerator function, and when the external device is disconnected as described above, the expansion board 2
Instead, a sequence program (ladder program) stored in the user program memory 23 is executed. Therefore, in this case,
Only limited processing is performed.

Next, the operation of the soft PLC of this embodiment will be described with reference to the flowchart of FIG.

After the power is turned on, the software PLC main body and the expansion board are initialized, and control processing of the external device is started (step 110).

Thereafter, the sequence engine 22 constantly determines whether or not a failure has occurred by the shake hand method as described above while controlling the external device (step 120).

When the sequence engine 22 detects a failure (Step 120; Y), it uses the bus controller 21 to prohibit data read / write access to the I / O memory 5 of the MPU 1 (Step 13).
0).

Thereafter, the sequence engine 22 determines whether write access is necessary (step 1).
40) On the other hand, if there is no need for write access (step 140, N), the soft PLC itself is stopped and the process is terminated (step 150), while if there is a need for write access (step 140, Y). ),further,
It is determined whether or not the I / O needs to be updated (step 160).

When the sequence engine 22 determines that the I / O needs to be updated (step 160;
Y), update the I / O memory as described above, return to step 120, and perform the same processing as above,
If it is determined that there is no need to update the I / O (step 160; N), the process proceeds to step 150, where the soft PLC itself is stopped and the process is terminated.

The software PLC of the above-described embodiment performs failure detection, I / O update, and I / O protection by mounting one expansion board 2 as shown in model 1 in FIG. , A board for processing failure detection and I / O update, and a board for processing I / O protection (a portion surrounded by a chain line is a single board). Similarly, even when two boards perform fault detection, I / O update, and I / O protection, as shown in model 2, a board that processes fault detection, and I / O update and I / O protection are performed. It may be configured to include a board that processes the / O protection.

Here, the above-mentioned configuration has a PCI bus as an expansion bus, and each board can access another board as a bus master. In addition, transmission of necessary information between the boards is performed by reading and writing to registers mounted on each board.

The above-described embodiment is the case of the model 3.

According to the control device of this embodiment, every time the timer 25 elapses a predetermined time, the code stored in the handshake memory 26 is read out, and if the read out code is not the predetermined code stored by the MPU 1 In order to determine that the software is running away,
Software runaway can be detected quickly.

When software runaway is detected,
Since a predetermined external device is disconnected, malfunction of the external device due to runaway of software can be prevented.

Thereafter, when a predetermined external device is disconnected,
Since the external device executes the preset processing, the external device system does not stop.

[0053]

As described above, according to the present invention, when an expansion board mounted on a personal computer detects a software runaway, a predetermined external device is disconnected, thereby preventing a malfunction of the external device due to a software runaway. can do.

In particular, every time the timer elapses a predetermined time,
The code stored in the memory is read, and if the read code is not the predetermined code stored by the MPU, it is determined that the software is out of control.
Software runaway can be detected quickly.

Further, when a predetermined external device is disconnected,
Since the external device executes the preset processing, it is possible to execute a limited function without preventing the external device system from being completely stopped.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a programmable controller according to the present invention.

FIG. 2 is an explanatory diagram of a handshake method as a method of detecting a failure.

FIG. 3 is a flowchart showing the operation of the programmable controller according to the embodiment.

FIG. 4 is a diagram showing another model.

[Explanation of symbols]

 1 MPU 2 Expansion Board 3 System Program Memory (SM) 4 User Program Memory (UM) 5 I / O Memory 6 I / O Circuit 21 Bus Controller 22 Sequence Engine 23 User Program Memory (UM) 24 Data Memory (DM) 25 Timer 26 Handshake memory (HM)

Claims (5)

[Claims] 1. A programmable controller for controlling an external device using a personal computer operated under the control of a general-purpose OS, wherein the personal computer has an expansion board, and the expansion board detects a software runaway. Detection means; I / O protection means for disconnecting a predetermined external device when the runaway detection means detects software runaway transmission; and when a predetermined external device is disconnected by the I / O protection means,
I / O updating means for causing an external device to execute a preset process. A programmable controller, comprising: 2. The runaway detection means includes code storage means for storing a predetermined code at predetermined time intervals by an MPU provided in the personal computer, and a timer for measuring time. Every time a predetermined time elapses, reads the code stored in the code storage means. If the read code is not the predetermined code stored by the MPU, it is determined that the software is out of control. On the other hand, if the read code is a predetermined code stored by the MPU, the software determines that no runaway has occurred and clears the code. controller. 3. The I / O protection means, when a software runaway is detected by the runaway detection means, an IPU storing data indicating an operation of an external device to an MPU provided in the personal computer. 2. The programmable controller according to claim 1, wherein access to the / O memory is prohibited. 4. The I / O updating means includes fail-safe data storage means for storing fail-safe data when software runaway is detected, and the fail-safe data stored in the fail-safe data storage means. 2. The method according to claim 1, wherein the safe data is rewritten and updated in an I / O memory storing data indicating an operation of an external device, and then the MPU is permitted to access the I / O memory. Programmable controller. 5. The programmable controller according to claim 1, wherein said extension board has a sequence engine.