JPH06259113A - Automatic changing device for sequencer ladder circuit - Google Patents

Abstract

PURPOSE:To provide an automatic changing device for sequencer ladder circuit which can early detect the factor of trouble of the sequencer ladder circuit when a production line, etc., are driven by the sequencer ladder circuit. CONSTITUTION:An automatic changing device for sequencer ladder circuit is provided with the reader means 24 and 15 which read the designed sequencer ladder circuits, an inner coil selector means 20 which selects an inner coil out of the device used by the read sequencer ladder circuit, and the circuit changing means 21, 22, 23 and 26 which change the contact of the inner coil used by the sequencer ladder circuit into a conditional contact that decides an ON or OFF state of the inner coil when the selected inner coil satisfies the prescribed conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic change of a sequencer ladder circuit for rewriting a sequencer ladder circuit designed for a sequencer for controlling a manufacturing apparatus of a production line into a form that facilitates finding a failure location when a trouble occurs. It relates to the device.

[0002]

2. Description of the Related Art Conventionally, as a control device for a manufacturing apparatus on a manufacturing line, a sequencer equipped with a microcomputer has been widely used instead of a relay circuit. At this time, a circuit design by a sequencer ladder circuit, which is a software program expressed by using a relay ladder diagram which can directly use the conventional relay circuit design technique, has become mainstream. Since a large number of internal coils can be used in the sequencer ladder circuit, the designer often uses a large number of internal coils when designing the circuit, and the sequencer ladder circuit tends to be complicated.

As a result, the following problems have occurred. When a trouble occurs in the manufacturing equipment on the manufacturing line, it is necessary to investigate the reason why the output coil is not driven by the sequencer. Therefore, when the output coil is displayed on the screen device of the sequencer, the conditional contact for turning the output coil on and off is also displayed on the screen device of the sequencer.
At that time, the on / off state of each contact is displayed on the screen, for example, as shown in FIG.
As indicated by M1 of No. 1, it is indicated by an ON display or the like in the center of the contact point, so that the cause of the trouble can be found by looking at the screen display of the sequencer. If the contact that is the cause is the contact of the internal coil, the conditional contact of the internal coil is further displayed on the screen to pursue the cause contact that the internal coil does not turn on or off. Therefore, when the internal coil has a complicated structure, it is not displayed on the screen at one time, and it is necessary to write a necessary part, and the work is complicated.

As means for solving the problem, for example,
In JP-A-2-35503, a relay coil in a ladder diagram display in which the screen of the output coil and the condition contact circuit screen of the internal coil in question are stored at the same time and can be arbitrarily switched to see both screens Has been proposed.

[0005]

However, the above technique has the following problems. (1) In recent years, the number of internal coils that can be used in a sequencer has dramatically increased as the cost of storage elements such as ROM has decreased, and some designers use a large number of internal coils to make a sequencer ladder circuit. The number of cases of designing is increasing. Designing with a large amount of internal coils
It is extremely convenient to increase the design flexibility and efficiently design the sequencer ladder circuit. That is, when designing a sequencer ladder circuit, it is possible to simplify each condition by making an internal coil that turns on and off according to some conditions and controlling the output coil etc. by the combination condition of the internal coils. is there. However, the designed sequencer ladder circuit tends to be complicated by the use of a large number of internal coils, and when many troubles occur, it is necessary to look at the sequencer screens. It was difficult to find the cause early.

(2) In particular, the sequencer used in the manufacturing line has become more sophisticated, and the trouble caused by the sequencer ladder circuit at a high frequency can be solved relatively easily. However, it is becoming more difficult to find out the cause of the problem, since it is mainly due to infrequent troubles. In addition, in order to investigate low-frequency troubles, the cause is found on the screen of the sequencer while operating the manufacturing line. It was difficult to find out the cause because it was always switched on and off.

(3) Further, in the conventional technique, if all sequencer ladder circuits connected under the AND condition are used, the cause of no output can be investigated, but if the output is performed when the output should not be performed. It was difficult to determine the cause. On the other hand, under all OR conditions, it was difficult to find out the cause of no output. And, when the OR condition and the AND condition are mixed, it is more difficult to investigate the cause.

The present invention has been made in order to solve the above-mentioned problems, and by automatically changing a designed sequencer ladder circuit, a sequencer ladder circuit is used to drive a manufacturing line or the like. It is an object of the present invention to provide an automatic changer for a sequencer ladder circuit that enables early detection of the cause of trouble in the sequencer ladder circuit.

[0009]

In order to achieve this object, an automatic sequencer ladder circuit changing device of the present invention is used in a read-in means for reading a designed sequencer ladder circuit and in the read sequencer ladder circuit. The internal coil selection means for selecting the internal coil from the device and the contact point of the internal coil used in the sequencer ladder circuit when the selected internal coil satisfies the predetermined condition. And circuit changing means for changing to a condition contact to be determined.

The sequencer ladder circuit automatic changing device of the present invention is the above-mentioned device, wherein the predetermined condition is (1) that the circuit for deciding on / off of the internal coil does not include a self-holding circuit, 2) A circuit that determines the ON / OFF of the internal coil is a load instruction, a load inverse instruction, an AND instruction, an AND inverse instruction, an OR instruction, an OR inverse instruction, an AND block instruction, an OR block instruction, a bush instruction, a read instruction, and a pop instruction. 1) or a combination of 2 or more of (3), and (3) the ON / OFF state of the internal coil changes due to different timings of input signals input during one scan of the sequencer ladder circuit. There are no conditions, and (1) and (2) of the three conditions,
Or (1), (2), and (3).

[0011]

The reading means of the automatic sequencer ladder circuit changing apparatus of the present invention having the above-mentioned structure reads the designed sequencer ladder circuit from the floppy disk and stores it in the sequencer ladder circuit storage means. Further, the internal coil selection means selects the internal coil from the device used in the read sequencer ladder circuit. Further, the circuit changing means changes the contact point of the internal coil used in the sequencer ladder circuit to a conditional contact point that determines on / off of the internal coil when the selected internal coil satisfies a predetermined condition. . Then, the sequencer ladder circuit writing means writes the changed sequencer ladder circuit on the floppy disk.

Here, as the means for judging the predetermined condition, there are a holding circuit judging means, a basic instruction judging means and a timing influence judging means. Of these, the holding circuit determination means determines that the circuit that determines the on / off state of the internal coil does not include a self-holding circuit. Further, in the basic command determining means, the circuit for determining the on / off of the internal coil includes a load command, a load inverse command, an AND command,
It is determined that it is composed of only one or a combination of two or more of an AND inverse instruction, an OR instruction, an OR inverse instruction, an AND block instruction, an OR block instruction, a BUSH instruction, a read instruction, and a pop instruction. Further, the timing influence determination means determines that the ON / OFF state of the internal coil does not change due to the difference in the timing of the input signal input during one scan of the sequencer ladder circuit.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram showing the configuration of the automatic changer for the sequencer ladder circuit. In this embodiment, a personal computer is used to configure an automatic changer for a sequencer ladder circuit. CPU that is a computing means
Reference numeral 11 denotes R0M19 for storing a plurality of programs, RAM 13 for temporarily storing data and the like, floppy disk reading device 15, and floppy disk writing device 1.
6 and the CRT 12 displaying the sequencer ladder circuit are connected.

R0M19 has an internal coil selection means 2
0, holding circuit determining means 21, basic instruction determining means 22, timing influence determining means 23, sequencer ladder circuit reading means 24, sequencer ladder circuit writing means 25, and circuit rewriting means 26 are programmed. Also,
The circuit rewriting means 25 includes an OR processing means 27 and an AND processing means 28. Further, the RAM 13 has a sequencer ladder circuit storage means 14 which is a storage area reserved for storing the sequencer ladder circuit.
Information is transmitted between the sequencer ladder circuit automatic changing device and the sequencer 18 by using the floppy disk 17
Via the programmer 18a. here,
The programmer 18a reads the program from the floppy disk 17 and rewrites the internal program of the sequencer 18, writes the program from the sequencer 18 to the floppy disk 17, and creates the program and writes the program to the sequencer 18. It has a function.

Next, the operation of the automatic changer for the sequencer ladder circuit having the above configuration will be described. 1 and 2 are flowcharts showing the basic operation of the automatic changing device. A sequencer ladder circuit for a manufacturing apparatus is designed by a device dedicated to designing a sequencer body or a sequencer ladder circuit. The designed sequencer ladder circuit is stored in the floppy disk 17. The floppy disk 17 is mounted on the floppy disk reading device 15 of the automatic changing device, and the designed sequencer ladder circuit is read by the sequencer ladder reading means 24 and stored in the sequencer ladder circuit storage means 14 (S1).
For example, when the sequencer ladder circuit shown in FIG. 5A is read, the sequencer ladder circuit is read in the form of the program shown in FIG. 5B.

Next, the loaded programs are sorted and
As shown in FIG. 6B, a table of devices, steps and states is created (S2). That is, the used step and the used state for each device that appears in sequence are created as a used device table. For example, show the step 0 and the step 8 where the first device, X1, is used.
Is used, the load (LD) of the a-contact in step 0, and the load (LD) of the a-contact in step 8 are described in the table. Next, as shown in FIG. 5A, a leading step, which is a starting step of a group of circuits, is created as a leading step table as shown in FIG. 6A (S3).

Next, the internal device used as a coil (this is called an internal coil) is taken out from the device table used (S4). This program is the internal coil selection means 20. In the example, M0 is used as the internal coil.
And M1 are retrieved. Next, it is confirmed that the condition contact that determines the on / off state of the taken out internal coil does not include a self-holding circuit (S5). This program is the holding circuit determination means 21. This is because when the self-holding circuit is included, the contact point of the internal coil cannot be changed to a conditional contact point that determines on / off of the internal coil. Therefore, if the internal coil contains a self-holding circuit, in the example M0
In the case of 1, one device is terminated without change and the process jumps to S28 (S6). If the internal coil does not include the self-holding circuit, in the case of M1 in the example, the process proceeds to S7 (S
5).

Next, it is judged whether or not the conditional contact for determining the ON / OFF of the internal coil consists of only one or a combination of two or more basic commands (S7). This program is the basic instruction determination means 22. In the example, X1 in step 8 which is a conditional contact for determining ON / OFF of the internal coil M1 is a load instruction, and X3 in step 10 is an AND inverse instruction, so both are basic instructions.
The internal coil M1 is determined to be a combination of only two basic instructions. Here, the basic instruction is a load instruction,
Load inverse instruction, AND instruction, AND inverse instruction, OR instruction, OR inverse instruction, AND block instruction, OR block instruction, Bush instruction, Read instruction,
The 11 commands of the pop command. The contents of each basic instruction are shown in the sequencer ladder circuit diagram in FIG.

Here, the basic instruction determining means 22 is required for the following reason. That is, recent sequencers can use various types of application instructions in addition to the basic instructions. However, 90% or more of the designed sequencer ladder circuit is usually composed of basic instructions,
This is because in order to achieve the object of the present invention, it is sufficient to rewrite the internal coil having the basic instruction as a conditional contact. On the contrary, if the application instruction is rewritten, the rewritten circuit becomes complicated and it becomes difficult to find the cause of the trouble. Therefore, in this embodiment, the basic command shown in FIG.
Although the twelve kinds of instructions described in (1) are used, the object of the present invention can be achieved by performing the increase / decrease and replacement of the basic instructions in accordance with the symmetrical sequencer ladder circuit. If the conditional contact that determines whether the internal coil is turned on or off includes the application instruction, one device is terminated without change and the process jumps to S28 (S8). If the conditional contact that determines on / off of the internal coil does not include an application command, in the case of M1 in the example, the process proceeds to S11 (S7).

Next, the number of devices at the condition contact that determines the on / off state of the internal coil is counted, and the number of devices is set to n (S11). The number of contacts with the same name as the device used as the internal coil is m (S
30). Next, the set condition number is compared with the above n, and when n is larger than the set condition number, the change is stopped and the process jumps to S28 (S46). This is because if the number of contacts is too large when the internal coil is changed to a contact, the internal screen will not be fully displayed when the internal coil is changed to a conditional contact, resulting in poor usability. In this embodiment, the number of setting conditions can be arbitrarily set to 1-5. The number of set conditions is compared with the above n, and when n is equal to or smaller than the number of set conditions, the process proceeds to S13 (S12).

Next, the circuit rewriting means 2 for rewriting the contact point of the internal coil into the conditional contact point for determining the on / off state of the internal coil.
6 will be described. RAM1 is a block A which is a condition contact that determines the on / off state of the internal coil to be changed.
3 is stored (S13). Next, the contact of the internal coil is searched for, and it is determined whether the contact is the a contact or the b contact (S14). In the case of a-contact, block A is stored as block B. Also,
In the case of the b contact, the logic of the block A is inverted and stored in the RAM 13 as the block B (S15).

Next, it is determined whether the contact point of the internal coil is used as an LD (S16), is used as an OR (S17), or is used as an AND (S19). . If it is neither LD, OR, nor AND instruction, one device is ended without change and the process jumps to S28 (S20). When it is used as an LD, it is left as it is (S16), when it is used as an OR, it is ORed by the OR processing means 27 (S18), and when it is used as an AND, it is ANDed by the AND processing means. Is performed (S21).
A method of OR processing and AND processing is shown in the flow chart of FIG. In the case of LD, it is left as it is because it is not necessary to change it in case of LD.

The OR process will be described. In the description here, the same applies to the a contact and the b contact. When the conditional contact of the block B has a one-circuit configuration including only LD and OR (S31), LD is simply changed to OR (S3).
2). If the final circuit is not AND or ANB (S34), the ORB instruction is only added (S35) unless the circuit is composed of only LD and OR. If the last is not AND or ANB (S34), the last is OR or OR
It is determined whether or not it is the B instruction (S36). If the last is not the OR or ORB instruction, the process is skipped and the process jumps to S26 (S37). If the last is an OR or ORB instruction, it goes back to find ANB or AND, and it is determined whether the immediately preceding ANB or AND found first is not an ORB (S38). If S38 is YES, the ORB is added immediately before the first found ANB or AND (S39), and the process proceeds to S40. If S38 is NO, S
Proceed to 40. In S40, LD is changed to OR.

Next, the AND process will be described. In the description here, the same applies to the a contact and the b contact. The condition contact of block B is LD and AND (or AN
In the case of one circuit configuration of only DI) (S31), LD is set to A
It is only changed to ND (S32). LD and AND
(Or ANDI) is not a single circuit configuration,
If the last is OR or ORB (S34), only an ANB instruction is added (S35). The last is OR or O
If it is not RB (S34), the last is AND or AN
It is determined whether or not it is the B instruction (S36). If the last is not the AND or ANB instruction, the process is skipped and the process jumps to S26 (S37). If the last is an AND or ANB instruction, there is an ORB or an OR if traced back, and it is determined whether the ORB or OR found first is not the ANB (S38). If S38 is YES, the ORB that is found for the first time or ANB is added before the OR (S
39), and proceeds to S40. If S38 is NO, S40
Go to. In S40, LD is changed to AND.

The program subjected to the above OR processing or AND processing is stored in the RAM 13 as a block C. As a result, the operation for substituting the condition contact stored in the block B for determining the on / off state of the internal coil in place of the contact of the internal coil is completed. In the example of the present embodiment, first, the internal coil M1 is used as the a-contact in the circuit of the coil Y1 and is therefore stored in the block B as it is. Next, since the contact is used in AND, A
ND processing is performed. That is, the LD instruction of X1 and X3
Since only one ANI instruction has a single circuit structure, LD is simply changed to AND, and the program is stored in the RAM 13 as a block C.

Next, it is confirmed that the ON / OFF state of the internal coil does not change due to the difference in the timing of the input signal input during one scan of the sequencer ladder circuit (S9). This program is the timing influence determination means 23. The contents are shown in the flow chart of FIG. Before explaining the operation of the flow chart,
A case where the on / off state of the internal coil changes due to different timing will be described with reference to a specific example in FIG. In the case of a direct-type sequencer, the on / off timing of the direct device XA such as an external sensor directly acts on the sequencer ladder circuit.

The on / off state of the internal coil M2 at step A differs depending on the timing at which the device XA is directly turned on. That is, considering the case where the contact M1 is conducting, the internal coil is divided into (1) when the XA is turned on during the A step and B step, and (2) when the XA is turned on after the B step. The on / off state of M2 is different.
In the case of (1), M2 enters the B step in the off state, and XA is on during that time, so XA2 does not conduct and coil Y1 is off. Next, when step A is executed,
Y1A is not conducting and the internal coil M2 is off.
In the case of (2), since XA is not turned on at the time of executing the B step, XA2 becomes conductive and Y1 is turned on.
Next, since XA is turned on by the time step A is executed, both XA1 and Y1A become conductive and M2 is turned on. In particular, when M2 is a holding circuit as shown by the dotted line in FIG. 11, the ON state is held. The same applies to the internal coil instead of the output coil Y1.

As described in the above example, the ON / OFF state of the internal coil may differ due to the difference in the timing of the input signal input during one scan of the sequencer ladder circuit. Normally, 1 scan is 10 ms or more
Although it is 100 ms, this is a problem when a machine or the like on the manufacturing line is controlled at a short timing. Particularly, when the internal coil M2 is a holding circuit, the holding state changes at an instant timing. Therefore, normally, as shown in FIG. 12, the internal coil M10 receives XA once, and the contact point of the internal coil M10 forms a circuit. When the internal coil used for that purpose is rewritten, the ON / OFF state of the internal coil returns to a different state due to the difference in the timing of the input signal input during one scan of the sequencer ladder circuit. In order to prevent this, the circuit is not changed in this embodiment.

Next, the method will be described with reference to the flowchart of FIG. Among the condition contacts that determine the on / off of the internal coil M, the direct device XA that is a direct device excluding internal devices such as the internal coil and is also used as a contact in the circuits of other coils is selected (S41).
At this time, the contact point of XA used in the internal coil M is XA1. Next, the coil Ym of another circuit in which the direct device XA is used as a contact is extracted (S4).
2). At this time, the contact point of XA is set to XA2. Next, it is determined whether or not the contact of the coil Ym is used as a condition contact for determining on / off of the internal coil M, that is, whether or not it is used in the circuit of the internal coil M (S4).
3).

If it is not used in the circuit of the internal coil M, it is memorized that there is no problem in timing. If it is used in the internal coil M, proceed to S44, YmA, XA
It is determined whether or not the state of the Ym coil when 1, XA2 and XA2 are made conductive matches the combination of FIG.
If they do not match the combination, remember that there is no problem with the timing. If the combination matches, the timing caution is stored (S45). The combination shown in FIG.
The algorithm conditions the case where the ON / OFF state of the internal coil differs due to the difference in the timing of the input signal input during one scan of the sequencer ladder circuit. If the timing caution is stored, the change is canceled and the process jumps to S26 (S1
0). If it is stored that there is no problem with the timing, the process proceeds to S23.

Next, the contact of the internal coil is changed to a conditional contact that determines the on / off state of the internal coil. That is, the block A is changed to the block C (S23). FIG. 7 (b) shows a modified version of the program shown in FIG. 4 (b).
Shown in. When this is shown by a sequencer ladder circuit, it becomes as shown in FIG. Next, use device, step,
The state table is changed (S24). Further, the circuit top step table is changed (S25). Next, it is determined whether or not all the contacts whose internal coils are used as contacts have been considered (S26). If not all have been considered, S14
Go to.

When all the contacts are examined, it is checked whether or not all the contacts have been changed as a result, that is, whether there is any contact that has not been changed (S29). When all the contacts of the internal coil are rewritten as contacts that determine the on / off state of the internal coil, one circuit using the internal coil as a coil is deleted (S27). At this time, naturally, the operations performed in S24 and S25 are simultaneously performed. Further, if any one contact that has not been changed remains, one circuit using the internal coil as a coil is left as it is. next,
It is determined whether or not all the internal coils have been checked (S28). Then, if there is an internal coil that is not checked, the process proceeds to S4. When all the internal coils have been checked, the change operation is finished and the program is written on the floppy disk by the program floppy disk writing device 16 of the new sequencer ladder circuit.

The changed program is read into the sequencer 18, and the production line is operated by the sequencer 18. As a result, when a trouble occurs, the sequencer screen is displayed, for example, as shown in FIG. 6 (a), so that the condition contacts that determine the on / off state of the internal coil can be checked simultaneously on one screen, It is not necessary to switch the screen of the sequencer, and it is possible to easily search for a problematic contact point. Thereby, the operating rate of the production line can be increased.

According to this embodiment, the contact of the internal coil used in the designed sequencer ladder circuit and satisfying the predetermined condition is automatically changed to the conditional contact for determining the on / off of the internal coil. When is displayed on the screen of the sequencer, the condition contacts of the output circuit hardly include the contacts of the internal coil, so that it is possible to quickly find a problem contact. Further, since the designer is not restricted in designing, the design efficiency of the sequencer ladder circuit can be increased.

The embodiments of the present invention are not limited to the above-mentioned embodiments, and various applications are possible. The automatic changer for the sequencer ladder circuit of the present invention can be incorporated in the sequencer main body, but in the present embodiment, a personal computer that is separate from the sequencer is used. This is because this device is used only when designing the sequencer ladder circuit and does not need to be used frequently, so that one device is sufficient for a plurality of sequencers. Further, in the present embodiment, all the conditions (1) to (3) are used as the predetermined conditions, but the three conditions may be appropriately combined and used. It is also possible to limit the automatic change depending on the amount of memory and the number of contacts after the change.

[0036]

As is apparent from the above description, according to the sequencer ladder circuit automatic changing apparatus of the present invention,
It is used in the designed sequencer ladder circuit, and the contact of the internal coil that satisfies the predetermined condition is automatically changed to the condition contact that determines the ON / OFF of the internal coil.When the output coil circuit is displayed on the sequencer screen, Since the condition contacts of the output circuit hardly include the contacts of the internal coil, it is possible to quickly find a problem contact when a trouble occurs. This is particularly effective when investigating the cause of trouble in the manufacturing apparatus while operating the manufacturing line, and can increase the operating rate of the manufacturing line. Further, since the designer is not restricted in designing, the design efficiency of the sequencer ladder circuit can be increased.

[Brief description of drawings]

FIG. 1 is a flowchart showing a first half of a basic operation of an automatic changing device for a sequencer ladder circuit which is an embodiment of the present invention.

FIG. 2 is a flowchart showing the latter half of the basic operation of the automatic changer for the sequencer ladder circuit according to the embodiment of the present invention.

FIG. 3 is a flowchart showing OR processing and AND processing.

FIG. 4 is a block diagram showing an overall configuration of an automatic changer for a sequencer ladder circuit.

FIG. 5 is a circuit diagram showing an example of a sequencer ladder circuit before change.

FIG. 6 is an explanatory diagram for explaining a changing method.

FIG. 7 is a circuit diagram showing an example of a modified sequencer ladder circuit.

FIG. 8 is an explanatory diagram showing basic instructions.

FIG. 9 is a flowchart showing the operation of the timing influence determination means.

FIG. 10 is an explanatory diagram showing conditions for timing attention.

FIG. 11 is a circuit diagram showing an example of timing attention.

FIG. 12 is a circuit diagram showing a conventional modified example of timing attention.

[Explanation of Codes] 11 CPU 13 RAM 14 Sequencer Ladder Circuit Storage Means 15 Floppy Disk Reader 16 Floppy Disk Writer 17 Floppy Disk 18 Sequencer 19 ROM 20 Internal Coil Selection Means 21 Holding Circuit Judging Means 22 Basic Command Judging Means 23 Timing Influence Judgment means 24 Sequencer ladder circuit reading means 25 Sequencer ladder circuit writing means 26 Circuit rewriting means 27 OR processing means 28 AND processing means

Claims (2)

[Claims] 1. A reading means for reading a designed sequencer ladder circuit, an internal coil selecting means for selecting an internal coil from a device used in the read sequencer ladder circuit, and the selected internal coil has a predetermined condition. Automatic sequencer ladder circuit characterized by having circuit changing means for changing the contact point of the internal coil used in the sequencer ladder circuit to a condition contact point for determining ON / OFF of the internal coil when Change device. 2. The device according to claim 1, wherein the predetermined condition is (1) that a circuit that determines ON / OFF of the internal coil does not include a self-holding circuit, and (2) ON / OFF of the internal coil. The circuit to be determined is one or more of a load instruction, a load inverse instruction, an AND instruction, an AND inverse instruction, an OR instruction, an OR inverse instruction, an AND block instruction, an OR block instruction, a bush instruction, a read instruction, and a pop instruction. And (3) the ON / OFF state of the internal coil does not change due to different timings of input signals input during one scan of the sequencer ladder circuit. (1) and (2), or (1), (2), and (3), Automatic changing device of Kensarada circuit.