JPH0863206A - Programmable controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a programmable controller that correctly stores data in a non-volatile storage unit even if a power failure occurs at any point during instruction execution. [Configuration] When the programmable controller 101 detects that the power failure detection signal ESG has reached a value indicating a power failure, the execution is completed if there is an instruction being executed in process F1, and then the next process should be executed in process F2. The instruction is read, and it is determined whether the instruction read out in the process F3 is in the same instruction group as the sequence control instruction group to which the executed instruction belongs. If it belongs to the same instruction group, the instruction read out is read out. After executing, return to process F2, and if they are not in the same command group, store the address of the storage means in which the command read out in process F5 was stored in the area of the non-volatile storage means. Equipped with 314.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to data for recording the state of a controlled object when a power failure of a power supply to its own circuit occurs,
The present invention relates to a programmable controller (abbreviated as PC in the following description) having means for storing these data in a non-volatile storage means in order to prevent the loss of data representing the progress of sequence control.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a PC having a function of preventing loss of data for recording the state of a controlled object and data for indicating the progress of sequence control when a power failure occurs.
In the following description, a binary signal corresponding to "0" or "1" is simply called a signal. In FIG. 4 (a), 1 is a PC, and PC1 is a control calculation means 2, a program storage means 3, a non-volatile storage means 4, a volatile storage means 5, a signal input circuit 6 (in the following description, simply an input circuit. 6), a signal output circuit 7 (hereinafter simply referred to as output circuit 7), a power supply circuit 8, a power failure detection circuit 9, and a display means 10.

The program storage means 3 is an IC ROM or a non-volatile RA whose power source can be switched to a battery in case of power failure.
It is made of M and stores a system program 31 and a sequence control program 32. The control calculation means 2 is a system program stored in the program storage means 3.
31 and the sequence control program 32 are executed, and the calculation result at the time of execution of the sequence control program is calculated by the calculation register 21 inside the control calculation means 2 (ACC21 in the following description
Abbreviated as). The system program 31 is a general system program that controls input / output and display,
It is a basic program including a program for initializing settings for sequence control and supporting execution of sequence control instructions. Sequence control program 32 is a PC
It is a control target sequence control program controlled by 1, and is constituted by one or more units of a unit sequence control instruction group consisting of two or more sequence control instructions. The non-volatile memory 4 is a RAM that can freely store and read data, and the power source for holding the memory is switched to a power source such as a battery in the event of a power failure, so that the memory is retained even when a power failure occurs. The volatile storage means 5 is a RAM
Although it is composed by, it is lost in memory in case of power failure. The signal SG input from the outside is input via the input circuit 6 under the control of the control calculation means 2, and the data represented by the signal SG is stored in the volatile storage means 5. The data output to the outside is stored in the output data area provided in the volatile storage means 5, and then output via the output circuit 7 under the control of the control calculation means 2. The power supply circuit 8 is a circuit that is supplied with power from a commercial AC power supply 11 and supplies DC power to the elements that make up the PC 1, and the power outage process in the PC 1 is completed even after the power supply from the AC power supply 11 is lost. It has the ability to supply power only for a sufficient period of time. The power failure detection circuit 9 is a circuit capable of detecting a power failure of the AC power supply 11 within a half cycle. In the case of a power failure, the power failure detection signal ESG is set to a value indicating the power failure detection within the latter half cycle of the power failure.

FIG. 4B is a diagram showing the division of data stored in the volatile storage means 4 and the non-volatile storage means 5. As shown in the figure, in the volatile storage means 5, an input data area 51 for storing the data indicated by the input signal, an internal relay area 52, an output relay area 53, and a general data area.
50 and are provided. The internal relay is a storage area with a 1-bit storage capacity that is used in the sequence control program as a function similar to an electromagnetically-operated relay, and the output relay holds 1-bit data output as a signal to the outside. This is the storage area for The non-volatile storage means 4 is provided with a keep relay area 41 and an area 40 of data that needs to be retained even in the case of a general power failure. The keep relay is a 1-bit storage area that stores 1 of a binary signal by a set signal and 0 by a reset signal, and has a function similar to that of a set / reset flip-flop or an electromagnetic operation keep relay.

As an example of the sequence control using the data stored in the volatile memory 5 by the PC 1 described above, FIG. 5 shows start / stop control of the motor M by the PC 1. FIG. 5A is a diagram showing the relationship between the PC1 shown in FIG. 4 and the external signals input / output to / from the PC1, in which 1 is PC, 21 is ACC, 5 is volatile storage means, and 51. Is an input data area, 53 is an output relay area, 6 is an input circuit,
Reference numeral 7 denotes an output circuit, which has the same reference numeral as shown in FIG. A signal for starting the motor M is input to the terminal F of the input circuit 6 from the normally open contact of the push button switch ST (hereinafter simply referred to as switch ST), and the terminal G is input to the push button switch SP (hereinafter referred to as the push button switch SP). In the description, a signal for stopping the motor M is input from the normally open contact of the switch SP).

An operation signal of the electromagnetic contactor Mt for opening and closing the motor M is output from the terminal Y1 of the output circuit 7, and signals from the terminals F and G are stored in the input data area 41 of the volatile storage means 4, respectively. Bitwise data areas F and G
(In the following description, the contents of the data area F will be referred to as data F, and the code attached to the data area will be used as the code of the data) and used as sequence control data. Further, the signal output from the terminal Y1 is an output relay area Y1 in 1-bit units of the volatile storage means 4 (in the following description, the code attached to the output relay area is used as the code of the data of the relay. ) Is a signal representing the same data.

FIG. 5B shows a PC1 for controlling the motor M.
NEMA (N representing the sequence control program stored in
ational Electrical Manufactures Association US
It is a sequence control diagram of an expression format called a ladder diagram, which is based on the expression according to A). In the figure, code F and code
The graphic symbol indicated by Y1A indicates that the data indicated by the symbol attached to the graphic symbol is to be processed, and the graphic symbol indicated by the symbol G is the inversion of the data indicated by the symbol attached to the graphic symbol. Indicates that the data of the processed value is to be processed, and the graphic symbol indicated by the symbol Y1 stores the processing result 1
It represents a bit data area, and the content of processing is represented by a diagram connecting the graphic symbols. The diagram showing the parallel connection shows the processing of the OR operation, and the diagram showing the series connection shows the processing of the AND operation. The processing sequence starts with the processing of the graphic data shown in the upper left corner, proceeds to the right, stores the processing result, and ends the series of processing. The sequence control program shown in this figure is executed by the PC 1 in the following itemized order. 1) The contents of data E are input and stored in ACC21 (see (a) in FIG. 5). If the switch ST is pressed, the normally open contact of the switch ST is closed, and the signal 1 indicating the closed circuit is input, so the data E becomes 1 and the AC
The content of C21 is also 1. 2) The data Y1A identical to the output data Y1 and the contents of ACC21 are OR-operated, and the operation result is stored in ACC21. If the switch ST is pressed, the contents of ACC21 are still one. 3) The data obtained by inverting the data G and the contents of ACC21 are AND-operated, and the result is stored in ACC21. switch
If SP is not pressed, the normally open contact remains open, the data G is 0, and the inverted data of this data becomes 1, so the result of the operation with the contents 1 of ACC21 before the AND operation is also 1 The content of ACC21 becomes 1. 4) The contents of ACC21 are stored in output relay Y1. AC
If the content of C21 is 1, the content of the output relay Y1 will also be 1.

The PC 1 also executes a sequence control program other than the above sequence control program, and executes the program.
At the end of execution, the contents of the output relay area 53 (see FIG. 4) are output to the outside. When the switch ST is pressed, the content of the output relay Y1 is 1 as described above, and thus the signal indicating this content causes the electromagnetic contactor Mt to close the power supply circuit of the motor M and the motor M is started. . When the output of the output relay ends, the PC1 returns to the beginning again and repeatedly executes the sequence control program. The time required to complete one cycle of this sequence control program is called cycle time, and the cycle time is usually several milliseconds. When the program of the sequence control diagram shown in Fig. 5 (b) is executed after the second round, the data Y1A is also 1 because the content of the output relay Y1 is 1, and the data E and data Y1A The result of the OR operation is 1 even if the normally open contact of the switch is opened and the data E becomes 0, and the following operation result does not change, so a so-called self-holding circuit is formed and the motor M
Is started by pressing the start push button switch ST once, and continues to rotate even after the operation of the switch ST is completed. When the rotation of the motor M is stopped, the switch SP is pushed. As a result of this operation, the data G becomes 1,
The result of the AND operation between ACC21 shown in Fig. 5 (b) and the data obtained by inverting the data G becomes 0, and this value is the output relay.
Since it is stored in Y1, a signal for opening the power supply circuit of the motor M is output from the terminal Y1 to the electromagnetic contactor Mt, and the motor M stops.

When a power failure occurs, the power failure detection circuit 9 (see FIG.
(Refer to (a)), the value of the power failure detection signal ESG is set to 0.
When this signal is input, the PC 1 completes the execution of the sequence control instruction currently being executed, stores the address of the next instruction to be executed in the non-volatile memory 4, and stops the execution of the instruction. After restarting the power supply, the PC1
Clears the content of the volatile storage means 5 (sets it to 0), refers to the address of the instruction to be executed first after the power failure stored in the non-volatile storage 4, reads the first instruction after the execution is restarted, Execution resumes from this instruction. In the execution cycle of the sequence control program after the restart, since the output relay area is provided in the volatile storage means 5, the content of the output relay Y1 is also 0, and the OR operation result of the data E and ACC21 is The value becomes 0, the motor M does not start unless the switch ST is operated, and the safety at the start of sequence control after a power failure is secured.

FIG. 6 shows an example of the sequence control by the PC 1 using the data stored in the nonvolatile memory 4.
FIG. 6A is a diagram showing the control purpose and the control means, and S0
Is a sensor that detects the starting position of the guided vehicle TC and sends a pulse signal SG0, Si (i is a number from 1 to 4 representing the sensor number,
In the figure, up to S3 is shown), the carrier TC is the section Ai (i
Is a sensor that detects a traveling end point of a section number (1 to 4) and transmits a pulse signal SGi (i is a signal number transmitted by the sensor Si). FIG. 6 (b) is a diagram showing the control contents, and indicates the remaining traveling strokes of the guided vehicle TC detected by the above-mentioned pulse signal SGi by the indicator lamp LAi (i are the indicator lamp numbers 1 to 4, It corresponds to the section number). When the guided vehicle TC starts, all the sections remain in the travel process, so all of the indicator lights LAi light up as a result of detection of the rising edge of the pulse signal SG0 sent by the sensor S0, and the guided vehicle TC goes to the section A2. In some cases, since the section A1 has already traveled, it is determined that the rising edge of the pulse signal SG1 transmitted by the sensor S1 is detected, the indicator light A1 is turned off, and the section A3
In the same way, the indicator lights A1 and A2 are turned off in the same way until the section A2 has been driven, and in the case of the section A4, the section A3
Until then, the indicator lights A1, A2, A3 are turned off.

FIG. 6C is a sequence control diagram for performing the above-mentioned display control. In the figure, Si is a volatile storage means 5.
It is data represented by the signal of the sensor Si stored in the input data area 51 (see FIG. 4). [SET Ki] (Ki is the keep relay, i is the number of this relay) is the program operation indicated by this symbol. When the value 1 is written in the keep relay Ki area, the contents of the keep relay Ki Indicates that the value becomes 1, and [RST Ki] is the arithmetic operation in the program shown by this symbol. When the value 1 is written in the area of the keep relay Ki, the contents of the keep relay Ki become 0. Is shown. When the content of the keep relay Ki becomes 1, this content is transferred to the output relay (not shown) for output, and the indicator light LAi lights up, and when it becomes 0, this content is transferred to the same output relay and output for output. LAi goes out.

A program for executing the contents of the sequence control diagram shown in FIG. 6C is executed by the PC 1 (see FIG. 4) as shown in the next itemized form. 1) The data SO is loaded into ACC21 (see Figure 4). The carrier vehicle TC departs from the starting point and uses the signal S0 as the signal SG.
Therefore, if the pulse signal SG0 is input to PC1, the data SO is 1, and the content of ACC21 becomes 1. 2) The contents of ACC21 are stored in keep relay K1. 3) Subsequently, the contents of ACC21 are stored in the keep relay K2. 4) Subsequently, the contents of ACC21 are stored in the keep relay K3. 4) Continuing on, the contents of ACC21 are kept relay.
Stored in K4. 5) Data S1 is loaded into ACC21 (see Figure 4),
Then, the contents of ACC21 are reset input of keep relay K1.
Although it is given as [RST K1], since the data S1 is 0 while the transport vehicle TC is in the section A1, the relay K1 is not reset and the content of the relay K1 is still 1. 6) Similarly, reset input to keep relay K2 [RST K2]
Is given as 0, and the content of the output relay K2 is still 1. 7) Similarly, reset input to keep relay K3 [RST K3]
Is given as 0, and the content of the output relay K3 continues to be 1.
Is. 8) Similarly, reset input to keep relay K4 [RST K3]
Is given as 0, and the content of the output relay K4 is still 1. As described above, as a result of executing the sequence control shown in (c) of FIG. 6, while the transport vehicle TC is in the section A1, the indicator light LAi
Lights up.

When the sensor S1 detects passage of the transport vehicle TC through the section A1, the content of the data S1 becomes 1 by the pulse signal SG1 input as the signal SG from the sensor S1. Since this signal is given as the reset input [RST K1] of the output relay K1, the relay K1 is reset and the content of this relay becomes 0, so that the indicator light LA1 is turned off and the transport vehicle TC has passed the section A1. I understand. Similarly, after each passage of the section, the indicator light representing the section goes out.

When a power failure occurs, since the data Si is stored in the volatile memory 5, it is cleared to 0 when the sequence control is restarted after the power is restored, but the keep relay Ki is a nonvolatile memory means. Since it is stored in No. 4 and holds the data before the power failure, this data is transferred to the output relay (not shown) and the position of the transport vehicle TC is correctly displayed.

[0015]

As described above, in the conventional programmable controller, the address of the sequence control instruction to be executed next to the last executed sequence control instruction at the time of power failure and the memory should be continued even at the time of power failure. Data and data are stored in the non-volatile storage means, and at the time of restart after a power failure, the execution of the instruction is restarted from the instruction next to the last sequence control instruction executed at the time of the power failure while referring to the data stored in the non-volatile storage means. . However, in the sequence control example shown in FIG. 6 (c), the content of the data S0 is 1, that is, the transport vehicle TC is in the section A1, and a power failure occurs during the process of writing the value 1 to [SET K2]. In case, keep relay
The contents of K1 and K2 are 1, but the contents of keep relays K3 and K4 remain 0, and the execution of the instruction is stopped. When the sequence control is restarted after the power is restored, the carrier SO has already started at this stage, so the data SO is 0, and the AC
The contents of C21 are also 0, so keep relays K3 and K4
1 is not written in. In other words, when the power is restored after a power failure, the indicator TC LA
3 and LA4 do not light up and display incorrectly.

In view of the above-mentioned circumstances, the present invention provides a programmable controller that correctly resumes sequence control after the power is restored no matter what stage of sequence control the power failure of the programmable controller during sequence control occurs. The purpose is to provide.

[0017]

In order to achieve the above-mentioned object, according to the present invention, a system program including a program for performing a process at the time of power failure, and a sequence control instruction in units of two or more sequence control instructions. It has a program storage means for storing a sequence control program consisting of one or more units of the group, a control calculation means for executing the program stored in the program storage means, and a function of holding the stored data even in the case of a power failure. A non-volatile memory means, a volatile memory means that does not have a function to retain the stored data in the event of a power failure, an input circuit, an output circuit, and a circuit for detecting a power failure. A programmable controller with the function of receiving a power failure detection signal and performing processing at power failure If a power failure is detected during execution of the program, the sequence control instructions at the time of the power failure detection are sequentially read until the next instruction of the sequence control instruction group at the time of the power failure detection that constitutes the sequence control program is read. Execute all sequence control commands included in the group, then store the address of the command to be executed first after the power is restored in the non-volatile storage means,
It is characterized in that the execution of the sequence control program being executed is stopped.

At the boundary between two consecutively executed sequence control instruction groups, the first instruction of the two instruction groups to be executed later loads the data into the arithmetic register of the control arithmetic means. It is preferable to determine by the fact that it is an instruction. Further, it is preferable to detect the last instruction of one control instruction group by determining that the instruction executed subsequently to this instruction is an instruction other than the sequence control instruction.

Further, when a power failure is detected during the execution of the program, it is determined whether or not the instruction related to the execution of the program at the time of the power failure detection is a sequence control instruction. Judging based on the address of the means, if this command is not a sequence control command, the address of the command that should be executed after the last executed command after the detection of power failure is executed first after the power is restored. Stored in the non-volatile storage as the address of the instruction,
It is preferable to stop the execution of the program.

[0020]

The programmable controller of the present invention, when a power failure is detected during execution of the sequence control program,
If an instruction is being executed at the time of power failure detection, the execution of this instruction is completed, the next instruction is read when the instruction execution is completed, and the sequence control instruction to which the instruction executed at the time of the power failure detection belongs It is determined whether or not the instruction belongs to the same instruction group as the group. If the instruction belongs to this sequence control instruction group, the read instruction is executed, and thus the read instruction is sequentially executed until an instruction not belonging to the sequence control program group at the time of power failure detection is read. When an instruction that does not belong to the sequence control program group at the time of power failure detection appears, the address of the program storage means in which this instruction is stored is stored in the non-volatile memory area and the execution of the instruction is stopped.

Further, if the instruction sequentially read by the programmable controller after the power failure is detected becomes an instruction to load the data into the arithmetic register of the control operation means, this instruction is added to the sequence control instruction program group which is being executed when the power failure is detected. Judge as the first instruction of the following sequence control instruction program group. Further, after the power failure is detected, it is determined whether or not the instruction sequentially read by the programmable controller belongs to the sequence control instruction. If the instruction does not belong to the sequence control instruction, the instruction before this instruction is executed when the power failure is detected. Judge as the last instruction in the sequence control instruction program group.

Furthermore, if a power failure is detected during execution of the program, the address at which the instruction relating to the execution of the program at the time of the power failure is stored is the address of the instruction belonging to the sequence control instruction. If this instruction is not a sequence control instruction, the storage address of the instruction that should be executed after the last executed instruction after a power failure is detected is the address of the instruction that is executed first after the power is restored. As a result, the program is stored in the non-volatile storage means and the program execution is stopped.

[0023]

【Example】

(Embodiment 1) FIG. 1 is a diagram showing a programmable controller 101 (abbreviated as PC 101 in the following description) of one embodiment of the present invention. PC101 is PC1 shown in FIG.
1 and FIG. 1 are the same except that the contents of the system program stored in the program storage means are different.
Only the type of system program in the PC 101 is shown in (a), and other parts will be described with reference to FIG.
In the figure, 312 is a general processing system program, 313 is a sequence control system program having the same specifications as the program stored in the system program 31 of the PC 1 shown in FIG.
The power failure processing program 314 is different from the program stored in the above-mentioned system program 31. 311 is a program including a program 314 for processing during power failure, a system program 313 for sequence control, and a system program 312 for general processing, and 301 is a system program 31.
1 is a program storage means for storing a sequence control program (not shown) and is the same except that the program storage means 3 shown in FIG. 4 and the stored system program are different.

FIG. 1 (b) is a flow chart showing the operation of the PC 101 when a power failure is detected by executing the power failure processing system program 314. Referring to this figure, P
The operation of C101 will be described. The PC 101 is a signal input from the power failure detection circuit 9 (see (a) in FIG. 4) during execution of the sequence control command that constitutes the sequence control program.
When the ESG detects a power failure and reaches 0, in process F1,
If there is a sequence control command that is being executed at that time, the execution of this command is completed, and when the execution of one command becomes a break, the next command to be executed is read in process F2 and read out in process F3. It is determined whether the specified instruction belongs to the same sequence control instruction group as the previous instruction. If they belong to the same program group, in the process F4, the read command is executed, after execution of this command, the process returns to the process F2 to read the next command, and the same process as the above-mentioned process is performed. If the instruction read out does not belong to the same sequence control program group as a result of the process F3, the address in the program storage means 301 in which this instruction is stored is stored in the nonvolatile storage means 4 ((b) in FIG. 4). (See (4) in Fig. 4), and stores it in the area 42 (see (b) in Fig. 4) that stores the address of the first instruction.
Stop program execution.

FIG. 2 is a diagram showing an example of a method of determining whether or not the read-out instruction belongs to the same sequence control instruction group as the previously executed sequence control instruction in the above-mentioned processing 3. is there. The figure shows an example of sequence control,
It is the figure expressed in the format of the ladder diagram mentioned above. In the ladder diagram, the sequence control program is shown in one frame from loading data to the operation register, performing the operation, and storing the operation result, as shown in boxes B1 to B4 surrounded by dotted lines in this example. A frame B1 surrounded by a dotted line is expressed as a set of sequence control instruction groups with the series of instruction groups
A group of sequence control instructions indicated by one of B4 to B4 is called one circuit. Sequence control instruction group B1 is shown in FIG.
By the same rules as described by Data A
Is first loaded into ACC21 (see FIG. 4), the result of the AND operation of the contents of ACC21 and the inverted data of data B1 is loaded into ACC21, and the contents of ACC21 are written into keep relay K1. Similarly, in the sequence control instruction group B1, the AND operation result of the contents of the data A and the inverted data of the data C is written to the keep relay K2 via the ACC21, and the contents of the data A and the data of the data D are written. The AND operation result with the inverted data is written in the keep relay K3 via the ACC21 to complete the instruction of this instruction group. In the sequence control instruction group B2 below, ACC
The sequence control instruction group B3 starts with an instruction to load the data ACC into the ACC21, and the sequence control instruction group B4 starts with an instruction to load the ACC21 with the data K.
As in this example, the first sequence control instruction of one sequence control instruction group is an instruction to load data into ACC21 without fail, and the instruction to load data into ACC21 does not appear in the second and subsequent sequence control instructions. Therefore,
PC21 when the instruction following the executed instruction is read out
Can determine the final instruction of the instruction group being executed by determining whether or not the read instruction is an instruction for loading data into ACC21.

When all of the sequence control instruction group is completed, as described above, the termination processing program BE for performing processing at the end of the sequence control cycle, such as outputting data of the output relay, based on the execution result of the sequence control instruction group. To execute. The beginning of this program is an instruction other than the sequence control instruction such as an instruction for loading data to be output to the outside and an instruction for shifting the execution of the instruction to the subroutine of the termination processing program BE. Therefore, the instruction read out after the sequence control instruction group is an instruction other than the sequence control instruction, for example, an instruction to load data, an instruction to change the execution order of the instruction to an order different from the storage address order of the instruction, etc. In this case, execution of the sequence control instruction group is completed, and it is determined that the next instruction is entered.

As an operation example when the PC 101 detects a power failure while executing the sequence control program, FIG.
During the execution of the program shown in the sequence control diagram shown in Fig. 4, the data S0 is stored in ACC21, the storage of ACC21 in the keep relay K1 is completed, and the power failure is detected while the contents of ACC21 are stored in the keep relay K2. To do. PC101 completes the execution of the instruction to store ACC21 in keep relay K2,
Then, as the next instruction, an instruction to store the contents of ACC21 in the keep relay K3 is read. This command ACCs data
Since it is not the instruction to load it into PC 21, the PC 101 executes the instruction to store the contents of ACC 21 in the keep relay K3. Similarly, an instruction to store the contents of ACC21 is executed for keep relay K4, and an instruction to load data S1 into ACC21 is read out as the next instruction. As described above, the PC 101 determines that the instruction for reading the data S1 into the ACC21 belongs to the next sequence control instruction group. Therefore, the address of the program storage means 3 (see FIG. 4) in which the read instruction is stored is determined. It is stored in the non-volatile storage means 4 (see FIG. 4), and execution of the instruction is stopped. Therefore, even if a power failure occurs during execution of this sequence control instruction group, the key relay
The same data is stored in K1 to K4, and keep relay K1 to K4
There is no inconsistency in the data of K4.

When all the processing of the sequence control instruction group is completed, the execution shifts to the termination processing program BE. PC101
If the instruction following the sequence control instruction after completion of execution is an instruction that belongs to the termination processing program BE such as an instruction to load data, the instruction immediately before this instruction is set as the last instruction of the sequence control instruction group. judge. (Embodiment 2) FIG. 3 shows another embodiment of the present invention. In the figure, 102 is the PC of the present embodiment, and PC 102 is shown in FIG.
The PC 101 is the same as the PC 101 shown in FIG. 1A, except that the PC 101 shown in FIG. 1A and a program storage means 302 storing a system program 315 having a system program 316 for processing during power failure are provided.

FIG. 3B is a flow chart showing the operation of the PC 102 when a power failure is detected by executing the power failure processing system program 315. The operation of the PC 102 will be described with reference to this figure. When the signal ESG input from the power failure detection circuit 9 (see (a) in FIG. 4) during execution of an instruction reaches the value 0 at which a power failure is detected, the PC 102 determines that the instruction being executed at the time of power failure detection in process F0. If there is, the execution of this instruction is completed, and when the execution of one instruction becomes a break,
Next, the address of the program storage means 3 (see (a) of FIG. 4) which stores the address of the instruction to be executed is referred to. processing
In F01, it is determined from the instruction address referred to whether the next instruction to be executed is an instruction belonging to the initial setting, and if it is an instruction belonging to the initial setting, the address of the program storage means in which this instruction is stored is determined. It is stored in the nonvolatile storage means 4 (see (a) of FIG. 4) as an instruction address to be executed first after the power is restored. If it is in the instruction area of the sequence control instruction, execution of the instruction is shifted to the process F3 shown in FIG. 1 (b).

[0030]

As described above, according to the present invention, a system program including a program for processing a power failure and one or more units of a sequence control instruction group including two or more sequence control instructions as a unit are selected. A program storage means for storing the sequence control program, a control calculation means for executing the program stored in the program storage means, a non-volatile storage means having a function of holding the stored data even in the case of a power failure, In the event of a power failure, it is equipped with a volatile storage means that does not have a function for holding the stored data, an input circuit, and an output circuit, and has a circuit that detects a power failure. Input the power failure detection signal transmitted by this power failure detection circuit. Executes a sequence control program in a programmable controller that has the function of performing processing in the event of a power failure When a power failure is detected in the sequence control program, the sequence control program is configured to sequentially read the instructions until the next instruction after the sequence control instruction group at the time of the power failure detection is included in the sequence control instruction group at the time of the power failure detection. All sequence control commands are executed, then the address of the first command to be executed after power recovery is stored in the non-volatile memory, and the execution of the sequence control program being executed is stopped. After the execution of all the sequence control instruction groups is completed, the instruction execution is stopped, and after the power is restored, the execution of the instruction is restarted from the next sequence control instruction group. Therefore,
Provided is a programmable controller that always stores the same data in a data area in which the same data should be stored during normal operation regardless of a power failure.

Further, according to the second aspect of the present invention, the boundary between the two sequence control instruction groups to be executed in succession is set at the beginning of the instruction group to be executed later in the two instruction groups. Since the instruction is determined by the instruction to load the data to the arithmetic register of the control arithmetic means, even if the existing program created based on the ladder diagram representation is executed as it is, the programmable program that operates correctly when a power failure occurs A controller is provided.

Further, according to the invention described in claim 3 of the present invention, the last instruction of one control instruction group is an instruction executed subsequent to this instruction is an instruction other than the sequence control instruction. Since the detection is performed by making a determination, a programmable controller is provided that operates correctly even when a power failure occurs other than when the sequence control instruction is executed. Further, according to the invention described in claim 4 of the present invention, when a power failure is detected during execution of the program, whether or not the instruction related to the execution of the program at the time of the power failure detection is a sequence control instruction. Whether or not this command is an instruction that does not belong to the sequence control command, it should be executed following the last executed command after the power failure is detected. The address of the instruction is stored in the non-volatile storage means as the address of the instruction to be executed first after the power is restored, and the execution of the program is stopped, so that it can operate correctly even if a power failure occurs during the initialization prior to sequence control. A controller is provided.

[Brief description of drawings]

1A and 1B are diagrams showing an embodiment of a programmable controller according to the invention described in claim 1, wherein FIG. 1A is a diagram showing contents of a system program of the programmable controller, and FIG. Flow chart showing the operation

FIG. 2 is a diagram showing a structure of a sequence control program executed in the programmable controller shown in FIG. 1 and a delimiter of a sequence control instruction group.

3A and 3B are diagrams showing an embodiment of a programmable controller according to the invention described in claim 3, wherein FIG. 3A is a diagram showing contents of a system program of the programmable controller, and FIG. Flow chart showing the operation

FIG. 4 is a diagram showing an example of a conventional programmable controller having a function of preventing data loss at the time of power failure, (a) is a block diagram of the programmable controller,
Figure (b) shows the contents of the data area of the programmable controller.

5A and 5B are diagrams showing an example of a program using data stored in a volatile storage means, FIG. 5A is an external connection diagram of the programmable controller shown in FIG. 4, and FIG. Sequence control diagram

6A and 6B are diagrams showing an example of a program using data stored in a non-volatile storage means, FIG. 6A is a diagram showing a control target, and FIG. 6B is a diagram showing signals used for sequence control and control. Diagram showing the relationship between the objectives, (c) is a sequence control diagram to achieve the control objective shown in (b)

[Explanation of symbols]

 101 Programmable controller 301 Program storage means 311 System program 314 Power failure processing system program 312 Sequence control system program 313 General processing system program

Claims (4)

[Claims] 1. A program storage means for storing a system program including a program for processing at the time of power failure, and a sequence control program consisting of one or more units of a sequence control instruction group including two or more sequence control instructions as a unit. A control calculation means for executing a program stored in the program storage means, a non-volatile storage means having a function of retaining stored data even in the case of a power failure, and a retention of data stored in the case of power failure. It is equipped with a volatile memory that does not have a function, an input circuit, and an output circuit, and is equipped with a circuit that detects a power failure. It has the function of receiving a power failure detection signal transmitted from this power failure detection circuit and performing processing during a power failure. In the programmable controller, if a power failure is detected while executing the sequence control program, Sequential instructions are read until the next instruction of the sequence control instruction group at the time of power failure detection, which constitutes the sequence control program, is read,
All sequence control instructions included in the sequence control instruction group at the time of the power failure detection are executed, and subsequently, the address of the instruction to be executed first after power recovery is stored in the non-volatile storage means, and the sequence in execution A programmable controller characterized by stopping the execution of a control program. 2. The programmable controller according to claim 1, wherein the boundary between two consecutively executed sequence control instruction groups is controlled by the first instruction of the instruction group to be executed later in the two instruction groups. A programmable controller characterized by being judged by an instruction to load data into an arithmetic register of an arithmetic means. 3. The programmable controller according to claim 1, wherein the last instruction of one control instruction group is determined to be an instruction other than the sequence control instruction, the instruction executed subsequently to this instruction. , A programmable controller characterized by detecting. 4. The programmable controller according to claim 1, wherein when a power failure is detected during execution of the program, whether or not the instruction involved in executing the program at the time of power failure detection is a sequence control instruction. , This instruction is judged based on the address of the storage means in which it is stored. If this instruction does not belong to the sequence control instruction, the instruction to be executed following the last executed instruction after the power failure is detected. A programmable controller characterized in that an address is stored in a non-volatile storage means as an address of an instruction to be executed first after power is restored, and execution of a program is stopped.