JPH09212201A - Control circuit for production equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a control circuit for production facilities which never breaks a metal mold, etc., of an injection molding machine at the time of system abnormality and is equipped with a safety function by forcibly stopping the facilities irrelevantly of a control signal from a processor and maintaining the state. SOLUTION: A holding circuit 5 holds a 1st reset signal outputted by a watchdog timer 2 and is composed of an inverter 13 and a D flip-flop 14. Further, a forcible stopping circuit 6 forcibly holds a load in a stop state with the held 1st reset signal and are composed of AND circuits 15 and 16. At the time of system abnormality, the injection molding machine holds the processor 1 in a reset state, forcibly stops the load such as a hydraulic motor, and holds the state. Consequently, the system is prevented from being restarted and the control circuit with the safety function which never breaks the metal mold, etc., can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for production equipment, such as an injection molding machine, which is provided with a safety function in a control equipment used for production equipment.

[0002]

2. Description of the Related Art Conventionally, for example, when a system abnormality occurs during the operation of an injection molding machine, a detection circuit such as a watchdog timer detects a runaway and resets the processor to restart the system. I was going.

FIG. 6 is a block diagram of a production equipment control circuit having such a conventional general safety function, and FIG. 7 is a timing chart when the system is abnormal.

In FIG. 6, 1 is a processor, 2 is a watchdog timer, 3 is an interface circuit, and FIGS. 7A and 7B show waveforms of respective parts.

The operation of the conventional production equipment control circuit having the above-mentioned safety function will be described below.

As shown in FIG. 7A, the processor 1 keeps issuing the clear pulse (a) to the watchdog timer 2 at regular intervals Ta. The processor 1 also writes data in the data latch circuit 11 of the interface circuit 3 to set the operation and stop of a load such as a hydraulic motor incorporated in the injection molding machine. Watchdog timer 2 even if Ta has passed for a certain period due to program runaway, etc.
Clear pulse (a) is not input to the
As shown in (b), when the runaway detection time Tb preset by the watchdog timer 2 is exceeded, the watchdog timer 2 outputs a reset signal (b) and OR
Reset the processor 1 through the circuit 4A. After releasing the reset, the processor 1 starts to operate again from the initial state,
It is configured to reboot the system.

[0007]

However, in the conventional configuration of the control circuit for the production equipment having the safety function, the system is restarted and resets normally after the reset by the watchdog timer only by the program runaway, but the processor etc. If there is an abnormality such as a hardware failure, the program may be operating normally, but depending on the hardware situation, it may be in an unpredictable mode after the system restarts. In the worst case, the mold could be damaged. Therefore, the safety of the device when a system abnormality occurs is required.

The present invention solves the above-mentioned conventional problems,
An object of the present invention is to provide a control circuit for a production facility having a safety function, which does not damage a mold or the like in an injection molding machine when the system is abnormal.

[0009]

In order to solve this problem, the production equipment control circuit according to the present invention forcibly stops the operation of the equipment regardless of the control signal from the processor and maintains the state. It has such a structure.

According to the present invention, it is possible to obtain a control circuit for a production facility having a safety function which does not damage a mold or the like in an injection molding machine when a system malfunction occurs.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention outputs a signal for controlling the above equipment based on data obtained by detecting the operating state of the equipment based on a preset program. Detects the processor, the watchdog timer that outputs a signal that resets the processor when a system error occurs, such as program runaway of this processor or hardware failure of the processor, and the first reset signal that is output from this watchdog timer. A holding circuit that holds the processor in a reset state by a detected signal, an interface circuit that outputs a control signal that operates equipment based on a control signal from the processor, and a first reset held by the holding circuit. Signal and a second reset signal input to the reset terminal of the processor Depending on the state of the above, it consists of a forced stop circuit that outputs a signal for forcibly stopping the equipment to the interface circuit regardless of the control signal from the processor, holds the processor in the reset state when the system is abnormal, and stops the equipment, It is configured to maintain that state.In the injection molding machine, the processor is held in the reset state, the operation of the load such as the hydraulic motor is forcibly stopped, and the system is restarted by holding the state. And has the effect of preventing damage to the mold and the like.

According to a second aspect of the present invention, in the first aspect of the present invention, the processor has a watchdog timer inside, and when the system is abnormal, a first reset signal output from the watchdog timer and at the time of power-on. And a delay circuit for delaying the reset signal when the power is turned on and transmitting it to the determination circuit. Has the same effect.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a block diagram showing a configuration of a production equipment control circuit according to Embodiment 1 of the present invention.

Since the embodiment shown in FIG. 1 has basically the same configuration as the conventional technique shown in FIG. 6, the same components are designated by the same reference numerals and detailed description thereof will be omitted. To do.

The holding circuit 5 holds the first reset signal output from the watchdog timer 2 and comprises an inverter 13 and a D flip-flop 14. The forced stop circuit 6 forcibly keeps the load in a stopped state by the held first reset signal, and is composed of AND circuits 15 and 16.

FIG. 2 shows a timing chart when a system abnormality occurs in the first embodiment, which corresponds to the waveforms of the respective parts (a) to (e) of FIG. In FIG.
(A) is a first reset signal (hereinafter referred to as a reset signal) output from the watchdog timer 2, (b)
Is a signal for detecting the reset signal (a) (hereinafter referred to as a reset detection signal), (c) is a signal output from the holding circuit 5 (hereinafter referred to as a reset holding signal), and (d) is a reset terminal of the processor 1. A second reset signal (hereinafter referred to as a system reset signal) input (e) is a signal output from the forced stop circuit 6 (hereinafter referred to as a forced stop signal).

The operation of the production equipment control circuit of the present embodiment configured as described above will be described below.

When the system is abnormal, the watchdog timer 2 outputs the reset signal (a) at "Lo" and resets the processor 1 by setting the reset terminal of the processor 1 to "Lo" through the OR circuit 4. At the same time, when the reset detection signal (b) obtained by inverting the reset signal (a) by the inverter 13 rises from “Lo” to “Hi”, the D flip-flop 14 outputs the reset hold signal (c) thereafter. "Lo". The reset hold signal (c) thus held is input to the processor 1 via the OR circuit 4 with the system reset signal (d) set to "Lo" to release the reset signal (a). After that, the reset state of the processor 1 can be maintained.

The forced stop circuit 6 is the interface circuit 3
In contrast, when the output of the AND circuit 15 is set to "Hi" to make the equipment operable, and when the output is set to "Lo" to make the equipment stop, when the system is abnormal, as described above. Since the reset hold signal (c) output from the D flip-flop 14 is held at "Lo",
The output of the ND circuit 16 becomes "Lo", and therefore the output of the AND circuit 15 also becomes "Lo".
The equipment will be forcibly stopped regardless of the data setting of 1. When the power is turned on, the system reset signal (d) is "Lo" and the output of the AND circuit 16 is "Lo". Therefore, the equipment can be stopped as in the case of the system abnormality.

Conversely, when the system is normal, the system reset signal (d) is "Hi" and the output of the D flip-flop 14 is also "Hi", so the output of the AND circuit 16 is "Hi". By setting the data of 11 to "Hi", both inputs of the AND circuit 15 become "Hi", so the output of the AND circuit 15 becomes "H".
i ”and the equipment is ready for operation.

As described above, according to the present embodiment, when the system abnormality occurs in the injection molding machine, the processor is held in the reset state, and the load such as the hydraulic motor is forcibly stopped, and the state is held. It is possible to realize a control circuit with a safety function that prevents the system from restarting and does not damage the mold or the like.

(Embodiment 2) FIG. 3 is a block diagram showing a configuration of a production equipment control circuit according to Embodiment 2 of the present invention.

Since the present embodiment shown in FIG. 3 has basically the same configuration as that of the first embodiment shown in FIG. 1,
The same components are assigned the same reference numerals and detailed description thereof will be omitted.

In FIG. 3, the processor 1 has a watchdog timer 2 inside and outputs a first reset signal to the inside and outside of the processor 1 when the system is abnormal. The delay circuit 7 delays the third reset signal when the power is turned on for a certain period of time, and an integrator circuit including resistors 21a and 21b and a capacitor 22 and inverters 23a and 23a.
b. The discriminating circuit 8 discriminates whether the power is turned on or not when the system is abnormal, and includes an AND circuit 24.

FIG. 4 shows a timing chart when an abnormality occurs in the present embodiment, which corresponds to the waveforms of the respective parts (a) to (f) of FIG. In FIG. 4, (a) is a system clock, (b) is a third reset signal when the power is turned on (hereinafter referred to as a power-on reset signal), and (c) is input to or output from the reset terminal of the processor 1. First reset signal (hereinafter referred to as system reset signal), (d) is a power-on reset delay signal,
(E) is a discrimination circuit output signal, and (f) is a reset hold signal. Further, FIG. 5 shows a timing chart when the power is turned on in the present embodiment.

The operation of the control circuit for production equipment of the present embodiment configured as described above will be described below.

Since the reset terminal of the processor 1 also serves as an input / output, it is necessary to input the power-on reset signal (b) when the power is turned on to the processor 1 by using an element of the open collector type.

In FIG. 3, power ON reset signal (b)
Is "Lo", the system reset signal (c) is also "L".
In order to achieve "o", the open collector type inverters 4a and 4b are used. Also, when the system is abnormal, the watchdog timer 2 inside the processor 1
The reset signal outputted from the processor 1 resets the inside of the processor 1 and also resets the external peripheral system by setting the system reset signal (c) to "Lo". At this time, the system reset signal (c) is held outside the processor 1 and is input to the processor 1 again. When holding the system reset signal (c), "Lo" is held both when the system is abnormal and when the power is turned on. Therefore, it is necessary to discriminate them so that they are not held when the power is turned on. Therefore, the discrimination circuit 8 is provided so that the holding circuit 5 operates only when the system is abnormal.

Explaining the operation at the time of system abnormality, the system reset signal (c) becomes "Lo" as described above as a method of discriminating at the time of system abnormality, but at this time, the power ON reset signal (b). Is "Hi" since the power has already been turned on, and it is determined that the system is abnormal under these conditions. The power-on reset signal (b) is input to the AND circuit 24 through the inverter 4b and the delay circuit 7, and when the other input of the AND circuit 24 is the system reset signal (c), both are "Lo", so the discrimination circuit output signal ( e) becomes "Hi", which is held at "Hi" in the D flip-flop 25 of the holding circuit 5 at the rising timing of the system clock (a). As a result, the open collector type inverter 4c
Through the reset signal "L" to the processor 1 again.
continue to output "o".

Further, the reset state is maintained even after the release of the reset output from the watchdog timer 2. The operation of the forced stop circuit 6 is similar to that of the first embodiment.

Next, the operation when the power is turned on will be described. As a method for discriminating when the power is turned on, both the system reset signal (c) and the power ON reset signal (b) are "Lo" as described above. Under these conditions, it is determined that the power is turned on. When the power is turned on, the power-on reset signal (b) becomes “Hi” after “Lo” during the reset period, so that the output of the inverter 4b becomes “Lo” after “Hi”.
become. On the other hand, the system reset signal (c) also becomes "Hi" after "Lo" during the reset period, but according to the present embodiment, both are "Lo" due to the delay of the inverter 4a.
It may be input to the D circuit 24, and in that case, the reset state may be retained as described above. Therefore, after the system reset signal (c) becomes "Hi", the power is turned on.
By delaying the signal of the inverter 4b sufficiently by the delay circuit 7 so that the N reset delay signal (d) changes from “Hi” to “Lo”, it is possible to prevent the reset holding state at power-on.

As described above, according to the present embodiment, even if the processor has a built-in watchdog timer, it is possible to realize the same control system for production equipment as in the first embodiment.

[0033]

As described above, the production equipment control circuit according to the present invention detects the operating state of the equipment based on a preset program, and outputs a signal for controlling the equipment based on the obtained data. And a watchdog timer that outputs a signal that resets the processor when a system abnormality occurs, and a holding circuit that detects the first reset signal output from the watchdog timer and that holds the processor in the reset state by the detected signal. ,
An interface circuit that outputs a control signal for operating the equipment based on a control signal from the processor, a state of the first reset signal held by the holding circuit and the second reset signal input to the reset terminal of the processor The interface circuit consists of a forced stop circuit that outputs a signal to forcibly stop the equipment regardless of the control signal from the processor, and if the processor has a watchdog timer inside, it will Discrimination circuit that discriminates the system state from the first reset signal output from the watchdog timer and the third reset signal when the power is turned on, and the third reset signal when the power is turned on is delayed and transmitted to the discrimination circuit Providing a delay circuit prevents the system from restarting when a system error occurs. It can be, for example, a large effect of the use in an injection molding machine can prevent damage such as mold is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a production equipment control circuit according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the production equipment control circuit according to the embodiment.

FIG. 3 is a block diagram showing a configuration of a production equipment control circuit according to a second embodiment of the present invention.

FIG. 4 is a timing chart for explaining the operation of the production equipment control circuit in the same embodiment when the system is abnormal.

FIG. 5 is a timing chart for explaining the operation of the production equipment control circuit according to the first embodiment when the power is turned on.

FIG. 6 is a block diagram showing a configuration of a conventional production equipment control circuit.

FIG. 7 is a timing chart explaining the operation when the system is abnormal.

[Explanation of Codes] 1 Processor 2 Watchdog Timer 3 Interface Circuit 4 OR Circuit 5 Holding Circuit 6 Forced Stop Circuit 7 Delay Circuit 8 Discrimination Circuit 11 Data Latch Circuit 12 Output Buffer 13 Inverter 14 D Flip-Flop 15, 16 AND Circuit

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Tsutomu Sakuma 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A processor that outputs a signal for controlling the equipment based on data obtained by detecting an operating state of the equipment based on a preset program, a program runaway of the processor, and a hardware failure of the processor. A watchdog timer that outputs a signal to reset the processor when a system abnormality occurs, and a first reset signal that is output from this watchdog timer is detected, and the signal that is detected is used to hold the processor in the reset state. A circuit, an interface circuit that outputs a control signal for operating equipment based on a control signal from the processor, a first reset signal held by the holding circuit, and a second reset input to a reset terminal of the processor Depending on the signal status, the above interface circuit On the other hand, it consists of a forced stop circuit that outputs a signal that forcibly stops the equipment regardless of the control signal from the processor, and is configured to hold the processor in the reset state and stop the equipment and maintain that state when the system is abnormal. Control circuit for production equipment. 2. A discriminating circuit in which a processor has a watchdog timer therein and discriminates a system state by a first reset signal output from the watchdog timer and a third reset signal at power-on when the system is abnormal. 2. The control circuit for production equipment according to claim 1, further comprising a delay circuit for delaying the third reset signal when the power is turned on and transmitting it to the determination circuit.