JP3978760B2 - Control device for duplicated equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to control of a duplexed device, and particularly provides a control device for a duplexed device that can set a service right to a side to be surely serviced without setting a request order. There is.
[0002]
[Prior art]
In the process control apparatus, in order to improve the reliability, two devices having the same function are provided, and these devices are operated alternately.
[0003]
Such a duplex control apparatus is shown in FIG. In FIG. 4, 5 is a duplex control device. Reference numerals 61 and 62 denote duplexing control units, which receive an ENA request signal (signal requesting a service right) from the host 9. Reference numeral 7 denotes a priority determination unit which receives service signals SERV1 and SERV2 from the duplex control units 61 and 62, respectively. Reference numerals 81 and 82 denote duplicated output units, and the priority determination unit 7 selects one of these output units. Reference numeral 9 denotes a host which outputs an ENA request signal to one of the duplexing control units 61 and 62.
[0004]
The priority determination unit 7 includes AND gates 71 and 73 and inverters 72 and 74. The service signal SERV 1 of the duplex control unit 61 is input to one input terminal of the AND gate 71, and its output is input to the output unit 81 and is inverted by the inverter 72 and is input to one input terminal of the AND gate 73. Entered. The service signal SERV2 of the duplex control unit 62 is input to the other input terminal of the AND gate 73, and the output thereof is input to the output unit 82, and is inverted by the inverter 74 to be input to the other input of the AND gate 71. Input to the terminal.
[0005]
That is, the AND gates 71 and 73 and the inverters 72 and 74 constitute a flip-flop. When the service signal SERV1 is at a high level and the SERV2 is at a low level, the output of the AND gate 71 is at a high level and the output of the AND gate 73 is at a low level, and this state is maintained even if the level of the SERV2 changes. Similarly, when SERV2 is at a high level and SERV1 is at a low level, the output of the AND gate 73 is at a high level and the output of the AND gate 71 is at a low level, and this state is maintained even if the level of SERV1 changes. That is, the outputs of the AND gates 71 and 73 are determined by the signal of SERV1 and SERV2 that has become high level earlier.
[0006]
The output unit 81 which is one of the duplicated devices is composed of a current signal generation unit 811 and an output control unit 812. The current signal generator 811 generates a 4-20 mA current signal, and this current signal is input to the output controller 812. The output of the AND gate 71 is input to the output control unit 812. When this signal is at a high level, the internal transistor 8121 is turned off and a current signal is output to the outside. When the output of the AND gate 71 is at a low level, the transistor 8121 is turned on and the current signal is bypassed by this transistor and is not output to the outside.
[0007]
The output unit 82 includes a current generation unit 821 and an output control unit 822. Since the operation is the same as that of the output unit 81, description thereof is omitted.
[0008]
Next, the operation of this duplex control device will be described. When the host 9 outputs an ENA request signal to the duplex control unit 61, the duplex control unit 61 asserts the service signal SERV1 to make it high level. At this time, if SERV2 is at a low level, the output of the AND gate 71 becomes a high level, the output of the AND gate 73 becomes a low level, and the current signal of the current signal generator 811 is output to the outside. Similarly, when the host 9 outputs an ENA request signal to the duplex control unit 62, the current signal of the current signal generation unit 821 is output to the outside. In this way, the host 9 outputs an ENA request signal to the duplexing control unit on the side to be operated, thereby operating any device among the duplexed devices (output unit) and disabling the other. Can be in action.
[0009]
[Problems to be solved by the invention]
However, such a duplex control device has the following problems.
As described above, the duplex control apparatus of FIG. 4 operates with the service right obtained by the device that has received the ENA request signal. Therefore, in order for the host 9 to pass the service right to the device on the specific side of the duplexed device, there is a problem that the timing for issuing the ENA request signal has to be controlled.
[0010]
For example, in order to first pass a service right to one device and then pass a service right to the other device, first output an ENA request signal to the duplexing control unit on the side that passes the service right, and then In addition, there is a problem that it is necessary to control to output an ENA request signal to the other duplex control unit.
[0011]
In such a case, particularly when a device corresponding to a gateway communicating asynchronously with the host 9 is interposed between the host 9 and the duplex control units 61 and 62, the host 9 sends an ENA request signal. Since it is difficult to control the transmission order of the devices, there is a problem that the service right cannot be practically given to a specific device.
[0012]
Therefore, the problem to be solved by the present invention is duplicated, in which even if it is difficult for the host to control the transmission order of the ENA request signal, the service right can be surely passed to a specific device. It is to provide a control device for equipment.
[0013]
[Means for Solving the Problems]
In order to solve such a problem, the present invention has the following configuration.
[0014]
According to the first aspect of the present invention, the output state is determined by the two duplex control units that output the service signal when the selection request signal is input, and the service signal that is input the service signal and is input first. And the duplexer control unit outputs a service signal as soon as a selection request signal is input, and selects a predetermined time. The service signal is output even if the request signal is not input. It is not necessary to consider the order in which the selection request signals to be input to the duplex control unit are transmitted. By using a flip-flop as the priority determination unit, the priority determination unit can be configured easily.
[0016]
The invention according to claim 2 is the invention according to claim 1 , wherein the timer unit whose operation and non-operation are controlled by the duplex control unit is used, and the selection request signal is not input to the duplex control unit. When the timer unit is operated and the timer unit outputs a time-up signal, the duplex control unit outputs a service signal.
[0017]
The invention according to claim 3 is the invention according to claim 1 or 2 , further comprising: a signal generation unit; and an output control unit to which an output signal of the signal generation unit is input. The output control unit is controlled to output or not output the output signal of the signal generation unit.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a duplex control apparatus according to the present invention. The same elements as those in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 1, reference numeral 1 denotes a duplex control device. Reference numerals 21 and 22 denote duplexing control units, which have substantially the same functions as the duplexing control units 61 and 62 in FIG. 4 except for control of timer units 23 and 24 described later. That is, the ENA request signal is input from the host 9 and the SERV1 signal or the SERV2 signal is output to the AND gate 71 or 73. 23 and 24 are timer units, which continue the timer operation while the trigger signals from the duplex control units 21 and 22 are active, and when the timer unit operates for a predetermined time, the time-up signal is sent to the duplex control unit 21, 22 for output.
[0019]
Next, the operation of this embodiment will be described with reference to the flowchart of FIG. In addition, since the group of the duplexing control unit 21 and the output unit 81 and the group of the duplexing control unit 22 and the output unit 82 have the same function, the former will be mainly described. When the ENA request signal 1 becomes active, the duplex control unit 21 immediately sets the output signal SERV1 to the high level. If the ENA request signal 1 is not active, the trigger signal output to the timer unit 23 is activated. Thereby, the timer unit 23 performs a timer operation. When the time-up signal is output from the timer unit 23, the SERV1 signal is set to the high level. The time from when the timer unit 23 starts to operate until the time-up signal is output is set to a time sufficiently longer than the maximum interval between the two sets of access described above.
[0020]
Next, the operation of this embodiment will be described with reference to the time chart of FIG. In this figure, ENA request signals 1 and 2 are selection request signals input from the host 9 to the duplex control units 21 and 22, respectively. SERV1 and SERV2 are services output from the duplex control units 21 and 22, respectively. Represents a signal. The current output is a 4-20 mA signal output from the output control units 81 and 82, and the time indicates the passage of time.
[0021]
Prior to time t1, since the ENA request signals 1 and 2 are both at a low level, the outputs of the AND gates 71 and 73 are also at a low level. Therefore, neither current signal of the output units 81 and 82 is output. During this time, the timer units 23 and 24 are operating. Since the output of the ENA request signal 1 becomes active (high level) at time t1, SERV1 also becomes high level, and the current signal from the output unit 81 is output. Further, the timer unit 23 stops the timer operation.
[0022]
At time t2, the timer unit 24 times out and a time-up signal is output to the duplex control unit 22. In response to this signal, the duplex control unit 22 sets SERV2 to the high level. However, the output state of the priority determination unit 7 does not change, and the output unit 81 continues to output a current signal. After that, when the ENA request signal 1 becomes low level and SERV1 changes to low level, since SERV2 becomes high level at time t2, the current output of the output unit 81 is turned off, and the current signal of the output unit 82 Is output.
[0023]
Note that the configuration of the priority determination unit does not necessarily have a flip-flop configuration as shown in FIG. The point is that the output state may be changed only by the signal that has been activated first.
[0024]
In addition, the configuration of the device has been described as outputting a current signal in FIG. 1, but any device can be used as long as operation and non-operation can be controlled by input.
[0025]
【The invention's effect】
As is clear from the above description, the following effects can be expected according to the present invention .
[0026]
According to the first aspect of the present invention, the output state is determined by the two duplex control units that output the service signal when the selection request signal is input, and the service signal that is input by the service signal and that is input first. And the duplexer control unit outputs a service signal as soon as the selection request signal is input, for a predetermined period of time. The service signal is output even if the selection request signal is not input. There is an effect that the service right can be handed over to the side to be arbitrarily serviced without considering the order of sending the selection request signals to be input to the duplex control unit. In addition, since the flip-flop is used as the priority determination unit, the priority determination unit can be easily configured.
[0027]
If a device such as a gateway that operates asynchronously with the host is interposed between the host that outputs the selection request signal and the duplex control unit, the order of transmission of the selection request signal cannot be controlled on the host side. Is particularly effective. In addition, the host activates the selection request signal on the service side and deactivates the selection request signal on the standby side, so that even after an instantaneous power failure occurs, the host is independent of the transmission order of the selection request signal. There is also an effect that it can be started in the state immediately before the momentary power failure.
[0029]
According to the second aspect of the present invention, in the first aspect of the invention, the timer unit whose operation and non-operation are controlled by the duplexing control unit is used, and no selection request signal is input to the duplexing control unit. When the timer unit is operated and the timer unit outputs a time-up signal, the duplex control unit outputs a service signal. By using the timer, there is an effect that it can be operated easily and reliably.
[0030]
According to a third aspect of the present invention, in the first or second aspect of the present invention, as the configuration of the output unit, the output of the signal generation unit is controlled to be output or not output by the output control unit. There is an effect that the configuration of the output unit is simplified.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the present invention.
FIG. 3 is a time chart for explaining the operation of the present invention.
FIG. 4 is a configuration diagram of a conventional duplexing control device.
[Explanation of symbols]
1 Duplexing control device 21, 22 Duplexing control unit 23, 24 Timer unit 7 Priority determining unit 71, 73 AND gate 81, 82 Output unit

Claims (3)

In a control device for a duplexed device that sets a service right for the duplexed first and second devices,
A first duplex control unit that receives a first selection request signal for requesting a service right of the first device and outputs a first service signal;
A second duplex control unit that receives a second selection request signal for requesting a service right of the second device and outputs a second service signal;
A priority determining unit that receives the first and second service signals and outputs a selection signal for setting a service right in one of the first or second devices;
It said first and second duplex control unit outputs the service signal as soon as the selection request signal is input, and outputs the service signal when the selection request signal is not input after a predetermined time,
The priority determination unit includes first and second AND gates and first and second inverters,
The first service signal is input to one input terminal of the first AND gate, and an output thereof is output to the first device and is inverted by a first inverter to be input to the second AND gate. Is input to one of the input terminals of
The second service signal is input to the other input terminal of the second AND gate, and an output thereof is output to the second device, and is inverted by a second inverter to be the first AND gate. Is input to the other input terminal of
An apparatus for controlling a duplexed device, wherein the selection signal is output to a device corresponding to a service signal input first among the first and second service signals. It has a timer unit whose operation and non-operation are controlled by the duplex control unit, and when the selection request signal is not input to the duplex control unit, the timer unit is operated and the timer unit outputs a time-up signal then, the duplex controller control apparatus duplexed device according to claim 1, characterized in that so as to output a service signal. As the configuration of the equipment, a signal generator,
An output control unit for controlling the output signal of the signal generation unit to output or not to the outside,
Output control unit is duplicated according to claim 1 or 2, wherein the outputting the service right is set by the selection signal outputted from the priority determining unit the output signal to the outside Equipment control equipment.

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