JPH0325202Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sequence control device, and particularly to a sequence control device that controls a sequence control object such as a machine tool or an assembly machine in a stepwise manner.

Conventionally, this type of control device has a configuration as shown in FIG. In FIG. 1, 1 is an input circuit that receives position input signals taken out from limit switches, proximity switches, etc. provided in the mechanical system to be controlled, and 2 is an input condition storage circuit that stores input conditions corresponding to each successive step. , 3 is a comparison circuit composed of a step storage section 3A that stores the currently executed step number indicated by the input signal that has arrived, and an input condition comparison section 3B that compares the stored contents with the output of the input condition storage circuit 2. , 4 is an input condition storage circuit 2 as an output corresponding to each step.
An output storage circuit stores the output of , and 5 is an output circuit. Note that a system in which the input condition storage circuit 2, the comparison circuit 3, and the output storage circuit 4 are realized by computer software has also been used in the past.

The above configuration constitutes the control device main body 6,
An operation panel 7 is provided for this main body 6. The operation panel 7 has an operation circuit 7A for operating the sequence control device main body 6, a single-action operation circuit 7B, and an interlock circuit 7C.

Next, the operation will be explained. When the input condition corresponding to the sequence step read from the input condition storage circuit 2 at time _t0 matches the content of the input signal _S1 arriving at that time, the input condition for the next step is read from the input condition storage circuit 2. A step output _S2 representing the next step number is read out and output to the output storage circuit 4, and the output signal _S3 is sent from the output circuit 5 to the mechanical system as a drive output _S4 . This state is then maintained until the input condition corresponding to the step in question matches the content of the input signal _S1 at time _t1 , and when they match, the drive output _S4 for the next step is sent out from the output circuit 5. In this way, this sequence control device sequentially completes the step operations of the controlled object.

If the order control by the input condition storage circuit 2 is not used, only the necessary operation is designated and inputted by the operation circuit 7A of the operation panel 7, and the controlled object is caused to execute it.

As described above, conventional sequence control equipment obtains a judgment on the input conditions and incoming input signals at each step and moves to the next control step, so it cannot be used in a power-down state such as during a power outage or emergency stop. As a countermeasure against this, it was necessary to set up a power outage hold state and memorize the step number when the power went down. However, even with this power outage hold function, if the mechanical system to be controlled moves from its stopped position for some reason during a power outage, it may cause malfunctions and, in some cases, may lead to a runaway situation. There was a risk of damage to the controlled object. Similar problems occur not only when the power is down, but also when the operation panel 7 is temporarily stopped during step automatic operation.
A similar malfunction may occur when single-acting operation is performed.

Generally, when a control device is configured to perform individual operations using a single-acting switch on the operation panel 7, an interlock is also required for this single-acting switch. An interlock circuit using a relay must be added. For this reason, each sequence control device must be redesigned each time a machine to be controlled is manufactured, and even though the same sequence control device main body 6 can be used even if the controlled objects are different, The number of design man-hours and production man-hours did not decrease at all.

The present invention was made to eliminate the drawbacks of the conventional sequence control device as described above, and by providing an interlock circuit for output in the sequence control device, it is possible to prevent damage to the controlled object at all times. It can be easily controlled without fear, and
The present invention provides a sequence control device that does not require redesign or change of external wiring even if the controlled object changes.

An embodiment of the invention will be described below with reference to FIG. 2, in which parts corresponding to those in FIG. 1 are denoted by the same reference numerals. In this case, between the output storage circuit 4 and the output circuit 5, the step output sent from the comparison circuit (step compatible comparison circuit) 3 is received via the output storage circuit 4, and the interlock release condition corresponding to the step output is set. is read from the output corresponding input condition storage circuit 12 and compared with the input signal of the controlled object inputted through the input circuit 1, and when they match, a drive command is sent out from the output storage circuit along with the step output. An output-corresponding input condition comparison circuit 11 is provided, and the output-corresponding input condition storage circuit 12 stores interlock release conditions for the driving mechanical system and the controlled object as the transmission permission condition for the drive command corresponding to each step output. is memorized.

That is, an input condition storage circuit (step corresponding input condition storage circuit) 2 which stores corresponding input conditions for determining the next step's step motion for each step in sequence control, and input conditions from the controlled object via the input circuit 1 are provided. The input signal input from the step is compared with the input condition stored in the input condition storage circuit (step compatible input condition storage circuit) 2, and the step output is stored until they match, and when they match, the step output of the next step is The pair with the comparison circuit (step-compatible comparison circuit) 3 that sends out the output constitutes the step operation determination section for the next step, whereas the output-compatible input condition storage circuit 12 and the output-compatible input condition comparison circuit 11 The pair constitutes an interlock release determination section for the interlock release condition as the drive command transmission permission condition for the next step. This comparison circuit 11 receives the output signal S ₃ of the output storage circuit 4,
When the output corresponding input condition signal S ₁₁ of the output corresponding input condition storage circuit 12 and the output signal S ₁₂ of the input circuit 1 match, or when the output corresponding input condition signal S 12 of the output corresponding input condition storage circuit 12 matches, or the matched output signal S ₃ of the output storage circuit 4
is sent to the output circuit 5 as a drive command _S13 .

Here, the output corresponding input condition storage circuit 12 outputs to the comparison circuit 11 an output corresponding input condition signal _S11 corresponding to the output signal of the output storage circuit 4 which is sequentially inputted to the comparison circuit 11, and at this time, the comparison circuit 11 When the output signal S ₃ of the step to be executed this time is received from the output storage circuit 4, the output corresponding input condition signal S ₁₁ whose content is the input condition corresponding to the output signal is read out, and the input signal S ₁₂ that has arrived is read out. The contents are compared, and if they match, or if they match, the drive command _S13 to be executed this time is sent to the output circuit 5. However, unless the content of the input signal S ₁₂ matches the output corresponding input condition signal S ₁₁ of the storage circuit 12, or the output signal S ₃ of the output storage circuit 4 which does not match is not sent to the output circuit 5.

In the above configuration, the input condition storage circuit 2
For example, when transferring a part from conveyor A to conveyor B by hand, the step is lowered and the part is lowered to conveyor B. The step part is released and goes up. The step part is moved onto step conveyor A. On step conveyor A. In the sequence of descending to pick up the step part, ascending by grasping the step part, and moving onto the step conveyor B, the condition signal of the lower end of the hand is the input condition in the step, and the condition signal of the higher end of the hand is the input condition in the step. In the step, the status signal of the hand backward end is the input condition, in the step, the status signal of the hand falling end is the input condition, in the step, the status signal of the hand rising end is the input condition, and in the step, the status signal of the hand forward edge is input It is a condition.

The input condition storage circuit 2 stores these input conditions for each step. Therefore, the step memory circuit 3A memorizes the step at that time (for example, being at a step), and determines whether the step has been completed by input condition memory circuit 2.
Compares the contents of the current input with the step output.
S ₂ is output to the output storage circuit 4.

Further, the output corresponding input conditions stored in the output corresponding input condition storage circuit 12 have the following contents. In other words, if the output S ₃ output from the output storage circuit 4 or the output S ₁₇ output from the single-acting switch input circuit 13 is output as is, there is usually no problem, but for example, in the above sequence, if the output S 3 is If a placed part still remains without being ejected, or if a part is dropped and lost, output must be stopped (blocked) even during normal operation.

Of course, simple interlocks, such as only the rising edge when the hand moves forward, also need to stop outputting. The interlock release condition as a permission condition for sending a drive command to the next step, for example, in the above sequence, when the hand is lowered, a status signal indicating that the hand is at the forward end and there is no work on conveyor B is used. , or a status signal indicating that the hand is at the backward end and the hand is open (note that a status signal is not required as an interlock release condition when the hand is raised or transferred between conveyors) for each output. Input condition memory circuit 1
2, and outputs the final output as _S13 from the output corresponding input condition comparison circuit 11 only when the input matches the contents of this output corresponding input condition storage circuit 12.
The driving output 4 is output through an output circuit 5.

Further, at this time, the input condition comparison circuit 3B and the output corresponding input condition comparison circuit 11 respectively perform the following input condition matching comparison. That is, the input condition comparison circuit 3B only compares the input corresponding to the output _S3 output from the output storage circuit 4. For example, in the above sequence, if the input indicating that the hand has retreated in the step is be compared. In other words, whether the hand backward end input is turned ON or, depending on the case, whether the hand forward end input is turned ON is compared. Further, the output corresponding input condition comparison circuit 11 compares whether or not it is possible to output the output S ₃ output at that step as S ₁₃ as it is based on the state of the machine.

Therefore, although the output-corresponding input conditions are eventually called for each step during automatic operation, the input conditions corresponding to the output are called only when outputting the output.

Therefore, in normal operation, the output is performed as usual.

That is, in the above format, the contents of the step input condition output _S18 of the input condition storage circuit 2 are compared with the output _S12 of the input circuit 1 in the comparator circuit 3,
The steps are stored in the step memory circuit 3 until they match.
The step output S ₂ stored in A is output to the output storage circuit 4, and the output signal S ₃ is output to the output corresponding input condition comparison circuit 11.

At this time, the output corresponding input condition comparison circuit 11 reads out the output corresponding input condition signal _S11 containing the output corresponding input condition from the output corresponding input condition storage circuit ¹² based on the output signal _S3 , Compare with the content. If the results match, the comparison circuit 11
gives the output signal _S3 of the output storage circuit 4 to the output circuit 5 as a drive command _S13 . Therefore, the controlled object executes the step, and as a result, the content of the input signal _S1 changes, which is fed back to the input circuit 1, and the content of this input signal _S1 is used as the step input condition output S of the input condition storage circuit 2. ₁₈ , the step in the step memory circuit 3A is updated by one step, and the comparator circuit 3 no longer sends out the output _S2 .
Finish controlling this step.

Thereafter, when executing the next step as necessary, the comparison circuit 3 compares the input condition signal _S18 corresponding to the next step number and outputs the next step output _S2 until it matches the input signal _S12 . A control operation similar to that described above is executed.

In this way, the controlled object is sequentially controlled step by step to execute a series of tasks.

However, when the power goes down, the step number being executed at that time is stored in the step storage circuit 3. Therefore, when the power is restored and restarted, the step output S ₂ of this step memory circuit 3A
Based on this, the output storage circuit 4 outputs an output signal _S3 ,
The output corresponding input condition comparison circuit 11 receives the output signal of that step from the output corresponding input condition storage circuit 12.
The output corresponding input condition signal S ₁₁ corresponding to S ₃ is read out and compared with the input signal S ₁₂ of the control object currently being restarted, obtained from the input circuit 1. If they match, the output _S3 of the output storage circuit 4 is sent to the output circuit 5, whereas if they do not match, it is not sent.

Therefore, after the power is restored, if the steps in the sequence control are collapsed compared to the state before the power was turned off, the controlled object will not be activated, and thus the controlled object will not malfunction or run out of control.

In addition, when controlling the controlled object manually using the operation panel 7, the single-acting switch input circuit 13 is turned on using the selection output _S16 of the operating circuit 7A, and the single-acting output signals _S15 and _S2 are switched to single-acting. The operation circuit 7B may supply the output corresponding input condition comparison circuit 11, and the selection output _S15 may turn off the step output _S2 and the output signal _S3 .

In this way, the control target can be reliably manually controlled in the same manner as in the case of power down, and if there is a malfunction on the operation panel 7, the output S ₁₃ will not be obtained from the output compatible input condition comparison circuit 11.
There is no need for the controlled object to operate abnormally. Furthermore, when switching from single-acting operation to automatic operation, the transition can be made reliably.

In FIG. 2, the functions of the input condition storage circuit 2, the comparison circuit 3, the output storage circuit 5, the output-compatible input condition storage circuit 12, and the output-compatible input condition comparison circuit 11 may be executed by software.

As described above, according to the present invention, the input conditions corresponding to the control output are determined before sending the control output from the output circuit to the controlled object, so when restarting from an abnormal state during automatic operation, Alternatively, damage to the machine due to abnormal operation due to bounce of the controlled object during automatic operation can be prevented. In addition, it is possible to prevent abnormal operation at the time of restart due to erroneous operation in single-acting operation operation, and the single-acting operation circuit 7B
Since the interlock can be formed within this sequence control device, there is no need to prepare a separate interlock circuit, and the number of man-hours during design and manufacturing can be greatly reduced. In particular, as mentioned above, circuits 2, 3, 4, 1
The effect is particularly remarkable when 2 and 11 are configured by software. Furthermore, as a result, it is possible to configure a sequence control device that includes the operation panel 7 as a standard internal structure, thereby making it possible to further reduce the size of the overall structure of the sequence control device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional sequence control device, and FIG. 2 is a block diagram showing an example of a sequence control device according to the present invention. 1...Input circuit, 2...Input condition storage circuit, 3
... Comparison circuit, 3A ... Step storage section, 3B...
...Input condition comparison section, 4...Output storage circuit, 5...
Output circuit, 6... Sequence control device main body, 7...
...Operation panel, 7A...Operation circuit, 7B...Single acting operation circuit, 7C...Interlock circuit, 11...Output corresponding condition comparison circuit, 12...Output corresponding input condition storage circuit, 13...Single acting switch input circuit.

Claims (1)

[Claims for Utility Model Registration] (1) In a sequence control device that sequentially provides drive output in steps to a controlled object, corresponding input conditions for determining the step motion of the next step are set for each step in the sequence control. The step-corresponding input condition storage circuit stores the input signal input from the control object through the input circuit and compares it with the input condition stored in the step-corresponding input condition storage circuit, and outputs the step until they match. A step-corresponding comparison circuit that stores the step output and sends the step output of the next step when they match, an output storage circuit that stores the drive command corresponding to each step output, and a step-corresponding comparison circuit that stores the drive command corresponding to each step output. an output-compatible input condition storage circuit that stores interlock release conditions for the driving mechanical system and the controlled object as sending permission conditions; and a step output sent from the step-compatible comparison circuit; The interlock release condition corresponding to the step output is read from the output corresponding input condition storage circuit, and compared with the input signal of the controlled object inputted through the input circuit, and if they match, the step is released from the output storage circuit. An output-compatible input condition comparison circuit that sends out a drive command that is sent out together with the output, and an output circuit that outputs a drive command for the controlled object that is sent out from the output-compatible input condition comparison circuit in response to the step output. A sequence control device characterized by: (2) The sequence control device according to claim 1, which specifies only necessary operations by manually inputting the drive command from an operation panel and directly applying it through a single-acting switch input circuit.