JPH0430602B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a sequence control device (sequencer),
In particular, the present invention relates to a method for backing up a sequence control device that enables good backup when a momentary power outage occurs.

[Background of the invention]

The power supply to the sequence control device may experience a momentary power outage. There are two methods to deal with such instantaneous power outages. The first method is to use a smoothing capacitor that forms part of a rectifier circuit that supplies DC power. In this case, the smoothing capacitor is set to have a larger capacity than a normal smoothing capacitor. During a power outage, this smoothing capacitor is charged by the DC power supply. The rated power supply (voltage) maintenance time using a smoothing capacitor after a power outage is
Can be set to about 30msec. Therefore, this 30msec
During the power supply maintenance interval, the voltage charged in the smoothing capacitor is used as the power supply for the sequence control device. After 30 msec, the charge in the smoothing capacitor is discharged and falls below the rated value, so it cannot be used as a power source for the sequence control device. Therefore, during the period when the charging voltage of the smoothing capacitor is used as a power source, the sequence control device performs calculations and control in the same manner as before the power outage.

The second method is to stop the calculation at the same time as a power outage occurs, and restart the calculation when the power is restored.

Among the above methods, the first method continues calculation and control even when the controlled object malfunctions during a momentary power outage, which may cause incorrect external input to be taken in, which may cause processing errors. It has the disadvantage of

The second method is that even if the controlled object endures a momentary power outage and outputs a regular external input signal to the sequence control device,
Because the sequence controller has stopped calculation,
This method has the drawback of causing incorrect processing even if the calculation is restarted after recovery. Furthermore, in the second method, if the period in which the external input signal from the controlled object is not established due to a momentary power outage becomes long, the external input signal is not established even after the power is restored and the sequence control device resumes calculation. It's also possible.

In recent years, as sequence control has become faster and more computationally efficient, malfunctions due to the instantaneous power failures described above have become more prominent, causing abnormal stoppages in sequence control and errors in position control. Moreover, instantaneous power outages themselves are not necessarily frequent phenomena, so
In many cases, problems are difficult to reproduce, and countermeasures require time and effort. Furthermore, when designing the control system of a sequence control device, costs are also becoming an issue, as redundant equipment such as interlock circuits and uninterruptible power supplies are added to prevent instantaneous power outages.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a backup method for a sequence control device that enables countermeasures to be taken in consideration of the influence of the instantaneous power failure on input signals from a controlled object when a power failure occurs.

[Summary of the invention]

In order to achieve the above object, in the present invention, the input signal of the controlled object is established from the time when the power supply is restored for a period of time during which the input signal of the controlled object is not affected by the instantaneous power outage. and the remaining power maintenance time for the sequence control device during momentary power outage at set times T1, T2, and T3.
predetermined as

If the power is restored within the set time T1 from the moment when the power fails, the sequence logic operation of the sequence control device continues, and if the set time T1 is exceeded, the sequence control device Continue sequence logical operations. If the power is restored within the set time T3 after exceeding the set time from the instantaneous power outage, the set time T3 will continue from that point onwards.
2, the sequence logic operation of the sequence control device is stopped, and after this time T2 has elapsed, the sequence logic operation of the sequence control device is restarted.

In addition, in the case of an instantaneous power outage that exceeds the set time T3,
Reset the sequence controller.

[Embodiments of the invention]

FIG. 1 shows an embodiment of a sequence control device according to the present invention. When an instantaneous power outage occurs, this sequence control device temporarily stops the sequence calculation and turns off the power supply if the input signal is unstable due to the influence of the instantaneous power outage, depending on the state of the external input signal at the same time as the momentary power outage occurs. After the return, the system waits for the establishment of an input signal and restarts the calculation. The sequence control device 20 includes a calculation section 1, a program memory 2, an output circuit 3, an input circuit 4, a power supply section 5, and a soft timer 11. This soft timer 11 waits for the backup mechanism. The sequence control device 20 controls the control target 1
4, the input circuit 4 and the output circuit 3 communicate signals. These signals include status signals, command signals, etc. in addition to data.

The power supply section 5 waits for the power outage detection section 6 and automatically detects the power outage. The calculation unit 1 performs necessary calculations according to instructions stored in the program memory 2. The program memory 2 stores a sequence program. The input circuit 4 takes in state signals, various measurement signals, etc. from the controlled object 14 via the line 12, and sends them to the calculation unit 1 as input. Output circuit 3
receives the calculation output and control commands from the calculation unit 1 and outputs them to the controlled object 14 via the line 13.

The power outage detection section 6 generates a power outage detection signal 7 at the same time as a power outage occurs. This power outage detection signal 7 is
Input to soft timer 11 and set timer time T
1, T2, and T3. Further, the power outage detection signal 7 is input to the calculation unit 1 as an interrupt signal IRQ.

The timer time T1 in the soft timer 11 is
This is the time to decide how long after the instantaneous power outage occurs, the calculation will be put into a temporary halt state (hereinafter referred to as halt). The timer time T2 is a time period for holding the halt state. The timer time T3 is a time for monitoring the entire instantaneous power failure time and determining a range in which the operation of the sequence control device is guaranteed, that is, a remaining power supply maintenance time. T ₃ > T ₁ .

The soft timer 11 refers to a timer activated by software processing by the calculation unit 1. A timer starting program for starting the soft timer 11 is incorporated into a part of the program stored in the memory 2. This timer activation program is activated when a power failure detection signal from the power failure detection unit 6 is input to the calculation unit 1 as an interrupt signal IRQ.

The timer activation program is activated by the interrupt signal IRQ and sends the basic clock of the calculation unit 1 to the soft timer 11. Soft timer 1
1 counts this basic clock 15 and measures timer times T1, T2, and T3.

This soft timer 11 is an on-delay timer. That is, when the set elapsed time T1, T2, T3 has elapsed, a flag indicating that the time has expired is set, and the flag remains set until it is reset (so-called time-up state). It is a timer to

The operation will be explained below based on the time chart in FIG. 2 and the flow chart in FIG. Incidentally, the entire process shown in FIG. 3 can also be called a momentary power failure processing program. The reason why the processing division between the soft timer 11 and the arithmetic unit 1 is not clearly defined is because it is considered at a software level. In concept, the soft timer 11 and the calculation section 1 can also be collectively referred to as a calculation unit. At this time, the arithmetic processing in this arithmetic unit becomes the processing shown in FIG. Note that when referring to arithmetic processing, there are both sequence arithmetic processing and instantaneous power failure processing. Figure 3 shows the instantaneous power outage process as a whole.
Flows F11 and F13 are sequence calculation processes, and other flows are flows for instantaneous power failure processing.

Furthermore, FIG. 2 shows three cases of instantaneous power failure modes A, B, and C. (A section) < (B section) < (C two sections). Both are representative cases.
Therefore, although A, B, and C have the order of occurrence of A→B→C, this is for illustration only; the order may be in any combination, or only in a single mode (for example, A). may occur. In general, there are many cases of the latter.

This will be explained based on FIGS. 2 and 3.

Simultaneously with the occurrence of a momentary power outage, a power outage detection unit 6 detects this and outputs a detection signal 7. The detection signal 7 is input to the calculation unit 1 as an interrupt signal IRQ, and is also input to the soft timer 11. Arithmetic unit 1 receives an interrupt signal
It is determined that the IRQ is an interrupt due to power outage detection signal 7 (F2), and the timer activation program is activated.
As a result, soft timers T1 and T3 are activated (F3). The soft timers T1 and T3 count the basic clock 15 when activated.

The following operations will be explained in the order of instantaneous power failure modes A, B, and C.

(1) Regarding instantaneous power failure mode A.

Let t _a be the section of instantaneous power failure mode A, and t _a <T1. In this mode A, soft timer T1,
T3 never times up, and the power is restored at point P1 before the time-up. Therefore,
By flow F12, the previously set timer T
1, T3 is reset. In this mode A section, the sequence calculation is continued as is (F13). Therefore, a temporary stop (halt) state of the sequence operation does not appear.

(2) Regarding instantaneous power failure mode B.

The section of instantaneous power failure mode B is also t _b , and T1<t _b <
It is assumed that no power interruption occurs after T3 and T2.

Under this mode B, T1 always times up, and this can be detected in flow F5. When T1 times up, the sequence calculation is temporarily stopped (halt) (F6). The instantaneous interruption section is T1
This is because it was determined that the reliability of the sequence calculation was unacceptable because it continued until the time-up state. However, although the sequence calculation is temporarily stopped, the operating system as a computer is kept running. As a result, as is clear from Figure 3, the power outage process continues even after the sequence halt process (F7, F
8, F9, F10, F14, F15).

If the power is restored (P2) after the T1 time-up and before the T3 time-up, the timer T
1 and start timer T2 (F
7, F8). Until the timer T2 times up, the halt state of the sequence calculation continues. If the power is not cut off before this timer T2 times up,
At the time of T2 time up, the sequence operation is returned from stop to operation. That is, if there is no power interruption during the T2 interval, it is considered that there is no problem in terms of accuracy even if the sequence calculation is restarted after the T2 interval has elapsed.

(3) Regarding instantaneous power failure mode C.

It is assumed that the interval t _c of mode C is t _c >T3. Therefore, before timer T3 times out,
Power is not restored.

Now, the timers T1 and T3 are activated due to the power failure (F3), and the timer T1 times up while the power failure is being detected (F4). Sequence calculation stops (halt) due to T1 time up (F6)
becomes. After this stop, the power will not be restored, so T
1 reset, T2 startup processing (F8) does not occur.
Instead, the time-up of T3 is monitored (F14), and the sequence calculation continues to be stopped until the time-up of T3 occurs. Since the power has not been recovered yet at the time of T3, the sequence operation is switched from stop to reset at that point, and T1 and T3 are reset (F15).
Resetting a sequence operation means resetting the operation state up to that point, and also means that the sequencer is in a down state.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, sequence control calculations can be performed only while the input signal from the controlled object is established, and erroneous input signals from the controlled object are not taken in. ,
Moreover, it is possible to obtain a backup method for a sequence control device that allows control to continue in the same way as usual during a short-term instantaneous power outage of the sequence control device, and that can cope with a longer-term instantaneous power outage.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a time chart, and FIG. 3 is a processing flow chart. DESCRIPTION OF SYMBOLS 1... Arithmetic unit, 2... Program memory, 3... Output circuit, 4... Input circuit, 5... Power supply unit, 6... Power failure detection unit, 14... Controlled object, 20... Sequence control device.

Claims (1)

[Scope of Claims] 1. A sequence control device that takes in an input signal from a controlled object, performs a sequence logical operation, and sends the result of the operation to the controlled object to perform control, wherein the power supply of the sequence control device is momentarily interrupted. If the power supply is restored within a predetermined time T1 during which the input signal is not affected by the instantaneous power outage, the sequence logic operation of the sequence control device is continued; If the power supply is not restored within a period of time, the sequence logic operation of the sequence control device is stopped from the time when the set time T1 is exceeded, and the sequence logic operation of the sequence control device is stopped from the time when the set time T1 is exceeded from the moment when the momentary power outage occurs, and during the momentary power outage. When the power is restored within a predetermined remaining power maintenance time T3 for the sequence control device, the sequence control device continues to operate for a predetermined time T2 during which the input signal is established from the time of power restoration. A backup of the sequence control device that stops the sequence logic operation, restarts the sequence logic operation of the sequence control device after the set time T2 has elapsed, and resets the sequence control device in the event of a momentary power outage that exceeds the set time T3. Method.