JPH01142801A - Programmable controller backup device - Google Patents

Abstract

PURPOSE:To correct a shear in scanning time at the time of backup operation and to improve control accuracy by providing the title device with a timer means to be reset at the time of executing the copying operation of incomplete data by a pair of data storage means to restart time counting. CONSTITUTION:Incomplete data stored in a data storage device (DM) 15 on a control operation side are successively copied in a DM 25 on a controlled operation side every scanning time (ts) and the timer 5 repeatedly reset simultaneously with the start of copying. When a fault is generated in a CPU 11 or a program memory (PM) 12 in a normal system program controller PA at time t2 after a certain copying time t1, change-over switches S1-S3 are turned to the B side and a holding system programmable controller PB backs up the PA. At that time, the count value (td) of the timer 5 is read out and the time (td) required up to the start of backup operation is added to control data output time t3 to correct and output the incomplete data and control data. Consequently, control accuracy can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Field of Industrial Application) This invention relates to a backup device for a programmer controller.

(Prior Art) A programming controller, which is generally used as an instruction processing unit in a sequence control system, plays an important role in control processing, and therefore, there is a strong demand for reliability in its operation. . However, there is no such thing as a completely programmable controller, and it may become inoperable due to failure, destruction, or other causes, and in such cases, when used alone, there is a problem that the control itself becomes impossible due to the failure. .

Therefore, a standby programmable controller is provided as a backup device for the regular programmable controller as shown in Figure 4, and when an error occurs in the regular system, the bus is switched to the standby programmable controller to continue control. Programmable controller backup devices are known. .

To explain this conventional programmable controller backup device, the central processing unit (CPU) 1
1 and a program storage device (PM) 12 constitute a regular programmable controller PA, and a CPU 21 and PM22 constitute a standby programmable controller PB.
The programmable controller PA in the regular system normally operates, and when the regular system fails, the bus switching device 3 switches the input/output data bus from the bus 13 to the bus 23, and at the same time switches the memory bus from the bus 14 to the bus 24. The system switches to operate the standby system.

That is, normally the changeover switch 81 in the bus switching device 3
．． 82 and 83 are respectively located on the normal-use system contact A side, and the normal-use CPU 11 is coupled to the input/output device (Ilo) 4 via the I10 data bus 13, and performs control operations according to the program of the PM 12.

Further, intermediate data is held in a data storage device (DM) 15 connected via a memory bus 14, and this 0M
15 intermediate data are sequentially copied to the standby system 0M25.

If an abnormality occurs in the CPU 11 or PM 12 of the regular system PA in this state, the changeover switches 81, 32, 83 in the bus switching device 3 are immediately switched to the B side, and the CPLI 21 of the standby system programmable controller PB is switched to the I10 bus 2.
3 to l104 and memory bus 2
Control of the standby PB by the program of PM22 is continued using the normal intermediate data copied to this 0M25 via 0M25, and the operation of the regular PA is backed up by the standby PB. It is.

(Problem to be solved by the invention) In general, programmable controllers can run programs of several 10 m5 to several 1 using sequence commands and sophisticated operation commands.
It is repeatedly executed at a high speed of 0On+s. This repeated execution time is called scanning time (tS), and in the case of the backup device mentioned above, normally the 0M12 program is repeatedly executed at a cycle of After checking, only if there is no such data, the intermediate data of 0M15 is copied to 0M25, so that normal data is always held in 0M25.

Therefore, if we consider the scanning time ts when the backup operation is performed in this state, the fifth
As shown in the figure, control is normally performed at equal intervals by [S, and when control is performed to increase the output in proportion to time, the output changes linearly.

However, if a failure occurs on the PA side at time t2 during control and a backup operation is performed, the normal intermediate data immediately before the failure occurs is copied, and then the first intermediate data after backup is copied. Since the time td up to this point is different from the scanning time ts, the linearity of the output will be lost before and after this backup operation.

In other words, the regular PA transfers the intermediate data of 0M15 to 0M25.
A failure occurred at time t2 while the program of PM12 was being executed, and a backup operation was performed, and the normal intermediate data that had been copied to 0M25 of the standby PB was reversely copied to 0M15. When considering the time up to time t3 when the control is started, (t
3-t2) is constant, but since (j2-j+) is indefinite, td(=t3-t, ) also becomes indefinite.

As a result, with conventional programmable controller backup devices, if a backup operation occurs during control such as positioning, an output deviation δ occurs, resulting in a decrease in absolute position accuracy. There was a problem.

The present invention has been made to solve these conventional problems, and provides a programmable controller backup device that can correct the deviation in scanning time ts during backup operation and further improve control accuracy. The purpose is to provide.

[Structure of the Invention] (Means for Solving Problems) The programmable controller backup device of the present invention transfers the input/output data bus and memory bus to the standby programmable controller when the regular programmable controller becomes abnormal. It is connected to a bus switching means for switching to continue the control operation, and to each of the programmable controllers of the regular system and the standby system, the control operation side stores intermediate data, and the non-control operation side stores the data of the control operation side. The apparatus includes a set of data storage means for periodically copying the intermediate data, and a timer means that is reset when the intermediate data is copied in the set of data storage means and restarts time counting.

(Function) In the programmable controller backup device of the present invention, when the regular programmable controller is operating, the data storage means on the control operation side is reset at the time when data is copied to the data storage means on the non-control operation side, By using the timer means to start counting the time again, when a backup operation is performed, the timer means can accurately know the time from the time when the data was copied immediately before the backup operation until the occurrence of a failure, and using this recovery time. The stored data can be corrected.

(Example) Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which the same components as the backup device shown in the conventional example are denoted by the same reference numerals, and the CPU 11 and PM 12 are used as the regular programmable controller PA. provided,
CPU2 as standby programmable controller PB
1. PM22 is provided.

The bus switching device 3 is provided with a switch S1 for switching the I10 data bus 13.23, and switches S2 and 83 for switching the memory bus 14.24.
A timer 5 is provided which is reset at the start of the copy operation of 15.25 and performs a new time counting operation.

The operation of the programmable controller backup device having the above configuration will be described next.

In normal operation, the changeover switch 8 in the bus switching device 3
1, 82, and 33 are located on the A side, and the CPLJll of the regular programmable controller PΔ is coupled to I104 via the I10 bus 13, and control operations are performed according to the program of PM12.

Along with this, as shown in FIG. 2(a), the intermediate data D+
, D2... are held in 0M15 on the control operation side connected via the memory bus 14, and the intermediate data held in this 0M15 is sequentially transferred to DM25 on the non-control operation side every scanning time ts. The timer 5 is repeatedly reset at the same time as the copying starts.

As shown in FIG. 2(b), this timer 5 has a characteristic that when it is reset, it starts the time counting operation from 0. Therefore, as shown in FIG. 2(a), the intermediate data D+
, D2, . . . increase linearly, the scanning time [S]
, . . . are copied from 0M15 to D'M25. Suppose that a failure occurs in the CPU 11 or PM 12 at time t2 after copying time t1.
The selector switch S1゜32.83 is immediately switched to the B side, and as a result, the standby system PB backs up and the CPU2
1 continues control without stopping the system using the latest intermediate data during normal operation stored in 0M25.

At this time, the count value t of timer 5 at the start of backup
d was read and switched to the control operation side.0 The normal intermediate data copied to M25 was switched to the non-control operation side.
Time t3 when copying to M15 and outputting control data
In this step, the intermediate data and control data are corrected by taking into consideration the time td until the start of the backup operation and output.

Therefore, even if a failure occurs at an unspecified time t2, the backup operation time td can be determined by the timer 5, so the output is increased in proportion to the time as shown in FIG. 2(a). When controlling,
Even if a backup operation occurs during control of fl and lJ, the output data can be corrected by changing it linearly without causing the output deviation as shown in the conventional method shown in Fig. 5. This allows for improved accuracy.

FIG. 3 shows another embodiment of the present invention, in which a plurality of regular programmable controllers PA are used.

This is an example in which one standby programmable controller PB is used for a PC.

In this embodiment, each of the regular programmable controllers PA and PC has a central processing unit HffCPU1.
11,112 and program storage device PM121.122
The standby programmable controller PB consists of a CPU 21 and a PM 2 as in the above embodiment.
It is composed of 2.

In addition, bus switching devices 31 and 32 are provided for switching between the regular system programmable controllers PA and PC and the standby system programmable controller PB, respectively. The switching device 31 includes a switch S1 for switching the data bus 131.23 and a switch S2 . for switching the memory bus 141.24. S3 is provided.

11041 is connected to the changeover switch SL.

The data storage device DM151. A DM 251 is connected so as to be switched, and a timer 51 is also provided.

A changeover switch S1 is also installed in the bus switching device 32 for switching between the regular programmable controller PC and the standby programmable controller PB, so that the I10 data bus 132.23 can be switched and connected to the I1042. Further, changeover switches 82 and 83 for changing over the memory buses 142 and 24 are provided, so that the data storage devices DM152 and 252 can be changed over. And for this 0M152.252, timer 52
is provided.

To explain the operation of this second embodiment, during normal operation, the regular programmable controllers PA, P
The CPUs 111 and 11 operate according to the respective programs stored in the PMs 121 and 122.
2 operates, and the intermediate data stored in 0M151°152 is periodically copied to 0M151.252 at each scanning time js+ and ts2.

Now, if an abnormality occurs in one of the regular programmable controllers, such as a PC, and its operation stops, immediately switch 81, 82. S3 is switched to the B side and the standby programmable controller P
B will start a backup operation for the regular PC. Therefore, the CPLI 21 can continue operating based on the intermediate data that has been stored in the 0M252 and can continue control.

In this case as well, the timer 52 is reset every scanning time, and if a failure occurs at a certain point, the timer 52 counts the time starting from the previous copying point until the backup operation is completed, and based on this count value, the CP
U21 performs a correction calculation on the new intermediate data of the control data, supplies it to 0M252, and continues control.

Note that the present invention is not limited to the embodiment in which one standby programmable controller is provided for two regular programmable controllers as described above, and one standby programmable controller may be provided for more programmable controllers. Alternatively, it is also possible to provide one standby programmable controller for each regular programmable controller.

[Effects of the Invention] As described above, according to the present invention, a standby programmable controller is provided to the regular programmable controller so that the data bus and memory bus thereof can be switched and connected, and furthermore, data is transmitted in the middle at each scanning time. In addition to providing a data storage means that can copy the data, a timer that is reset at the time of data copying is provided to increase the time until the standby programmable controller starts backup operation in the event that the regular programmable controller fails. Because we are trying to measure
The count value of this timer can be used to correct intermediate data and perform control operations, making it possible to accurately control the undefined period of time until the regular programmable controller malfunctions after being copied at a certain point, unlike in the past. It is possible to accurately grasp the time required to capture data and start the backup operation, correct the data in the middle, and use it for highly accurate control.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of the above embodiment, Fig. 3 is a block diagram of another embodiment of the invention, and Fig. 4 is a block diagram of a conventional example. , FIG. 5 is an explanatory diagram of the operation of the conventional example. 11.111, 112, 212.21... Central processing unit (CPU) 12.121, 122.22... Program storage device (PM) 13.131, 132.23... Input/output data bus 14 .141, 142.24...Memory bus 15.1
51.152...Data storage device (DM) 25.25
1.252...Data storage device (DM) 3.31.3
2... Bus switching device 4.41.42... Input/output device 2i (Ilo) 5.51
．． 52...Timer 81.82.83...Switch

Claims (3)

[Claims] (1) Bus switching means that switches the input/output data bus and memory bus to the standby programmable controller side to continue control operation when the regular programmable controller becomes abnormal; a set of data storage means connected to the controller, for storing intermediate data on the control operation side and periodically copying intermediate data stored on the control operation side on the non-control operation side; A programmable controller backup device comprising: timer means that is reset during an intermediate data copy operation in a storage means and restarts time counting. (2) Provide one standby programmable controller for multiple regular programmable controllers,
2. The programmable controller backup device according to claim 1, wherein when one of the regular programmable controllers becomes abnormal, the bus switching means switches the connection to the standby programmable controller. (3) Claim 1 further comprises a correction means for correcting the intermediate data copied immediately before the occurrence of the abnormality to create new intermediate data according to the count time until the backup operation starts by the timer. Programmable controller backup device as described.