JP2000152350A - Duplicate transmission control method and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide duplicate transmission control, such as decision of an active system/a standby system and system changeover on the occurrence of faults without intervention of application on a controller. SOLUTION: The identical address is decide for duplicate control devices 2A, 2B and an identification number that can definitely identify each control device is decided, and an identification number of its own device and an opposite device is stored in the control devices 2A, 2B. When a control device rises, after a check frame to which an address and an identification number are added is broadcast, and when a response with respect to the check frame cannot received within a prescribed time, the device itself acts like an active system. Furthermore, when a control device acts as an active system and receives the frame from the other control device, the control device sends a check frame to the network as a response. When a control device receives a transmission response before becoming the active system and when the response includes an identification of the responded control device in pairs with the control device, the control device acts as a standby system, and when the response does not include the identification number, no transmission control is conducted afterwards.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplex transmission control method when a control device connected to a network is duplicated, and a control device therefor.

[0002]

2. Description of the Related Art In a petrochemical plant system for extracting gasoline, light oil, heavy oil, etc. by heating crude oil and increasing the heating temperature in stages, a temperature and quantity of crude oil at a certain point are set in a tank. And heating and post-processing according to each step are performed. For example, in the gasoline take-out step, the crude oil is heated to the gasoline volatilization temperature, the vaporized gasoline is led out through a pipe to a gasoline dedicated tank different from that for crude oil, and cooled to take out liquefied gasoline. When the amount of crude oil falls below a certain level, it is determined that gasoline has been taken out, and the heating temperature is raised to proceed to the next light oil take-out step. At this time, feedback control for constantly monitoring the temperature in the tank and keeping the heating temperature constant, and control for shifting to the next step are performed by the controller.

In such a plant system, control devices such as a temperature sensor, a crude oil amount sensor, and an output device for transmitting temperature information from a controller to a heating device are connected to a network, and exchange data with the controller via the network. Do. Control of each device when operating the above-mentioned plant is performed by an application program installed in the controller. In order to ensure the safety and reliability of the oil plant system, sensors are duplicated and installed in the tank, so that even if the service sensor fails, the temperature can be detected from the standby sensor and control can be continued. To Also, the temperature output device is duplicated,
Even if the service device fails, the standby device transmits temperature information to the heating device so that control can be continued.

[0004] When the control device is duplicated in this way, it is necessary to perform the duplication control, which is usually performed by a program on a controller (or a host computer). −318946
And Japanese Patent Application Laid-Open No. 10-21156.

[0005]

As in the above oil plant system, control devices and controllers such as sensors and temperature output devices are connected to a network, and data is transmitted between the control devices or between the control device and the controller via the network. Is a system for exchanging data.
When the redundancy control is performed by the application program on the controller, the equipment operating in a single
The application is changed even when the system is locally changed, such as the need for redundancy, and a problem arises in that the plant control must be temporarily stopped.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and eliminate the need for changing an application by changing a device configuration such as a duplex configuration. An object of the present invention is to provide a duplex transmission control method and a control device thereof, in which system switching can be performed without an application being conscious.

[0007]

According to the present invention, a controller is connected to a controller via a network, is provided for each control target device, and performs data transfer processing between the corresponding control target device and the controller. A duplex transmission control method in a duplex control device comprising two control devices, wherein two control devices of one duplex control device are given the same address on a network, Each control device has its own identification number that can be identified.
Each device of one redundant control device stores the identification numbers of its own device and the other device together, and when starting up the control device,
After broadcasting the address duplication check frame including the address of the own device and the identification number of the own device to the network, an address duplication check frame including the same address as the own device was not received from the other control device within a predetermined time. In some cases, the operation mode of the own device becomes a normal system, and then, when an address duplication check frame having the same address as the own device is received from another control device, an address duplication check frame including the address of the own device and the identification number of the own device is responded. The present invention discloses a duplex transmission control method characterized in that it is broadcast to a network.

Further, according to the present invention, an address duplication check frame including an address of the own device and an identification number of the own device is broadcast to the network when the control device is started up, and then the address duplication including the same address as the own device is performed within the set time. When a check frame is received, check whether the identification number included in the received address duplication check frame is the identification number of the control device paired with the own device, and check the identification number of the control device paired with the own device. In the case of, it is determined that the control device forming the pair has already started up as a normal system and has returned the response, and the own device enters an operation mode as a standby system and discloses a duplex transmission control method.

Further, according to the present invention, an address duplication check frame including an address of the own device and an identification number of the own device is broadcast to the network when the control device is started, and then the address duplication including the same address as the own device is performed within the set time. When a check frame is received, check whether the identification number included in the received address duplication check frame is the identification number of the control device paired with the own device, and check the identification number of the control device paired with the own device. If not, it is determined that another duplex control device having the same address as the address of the duplex control device including the own device exists and is already operating, and the own device performs transmission control. A redundant transmission control method is disclosed.

Further, the present invention is connected to a controller via a network, and is provided for each device to be controlled.
A control device constituting a redundant control device for performing a data transfer process between the corresponding control target device and the controller, and stores an address on the network having the same value as the paired control device. Register for storing the identification numbers of the own device and the control device forming a pair when an identification number having a different value is given to each control device, and a start-up of the own device First means for occasionally broadcasting an address duplication check frame including the address and identification number of the own device to the network, and the same address as that of the own device within a predetermined set time after broadcasting of the address duplication check frame by this means. A second means for outputting a received signal when an address duplication check frame including the received address duplicated check frame is received; A third means for setting the own device to a normal operation mode when not input, and an address of the own device when receiving an address duplication check frame including the same address as the own device after becoming a normal system. A fourth means for broadcasting an address duplication check frame including an identification number to the network as a response, and when the second means outputs "received", the identification number included in the received address duplication check frame is automatically transmitted to the network. A fifth means for checking whether or not the identification number of the control device forming a pair with the machine, and outputting the first signal if the identification number is a identification number of the control device forming a pair with the own machine; Sixth means for setting the own device as an operation mode as a standby system when one signal is output, and setting the own device to a normal system when the first signal is not output from the fifth means. A seventh means to avoid in standby, discloses a control apparatus having a.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows the second embodiment of the present invention.
This shows a schematic configuration example of a system to which the multiplex transmission control method is applied, and includes input devices 201A, 202B,.
20nA, 20nB, output devices 211A, 211B,.
.. 21nA and 21nB are connected to the network 3 as control devices, and perform input / output of data between the controller 1 and plant devices (not shown). Here, input devices 201A and 202B, 20nA and 20nB, output device 2
11A and 211B, 21nA and 21nB are 2
It is assumed that a heavy system is configured. Input device, output device,
Each of the controller and the controller has a built-in arithmetic processing unit and a storage device for data storage in order to perform communication according to a predetermined communication protocol. The controller 1 is, for example, a computer (a control process computer, a workstation, a personal computer, or the like) or a PC (programmable controller). Although the network 3 is shown as a bus type, it may be any type of network, or may use wireless or other communication means.

FIG. 1 shows a configuration of a duplicated control device. The control devices 2A and 2B are devices having the same control function,
For example, the input devices 201A and 201B or the output devices 211A and 211B in FIG. 2 are shown. Each of the control devices 2A and 2B has a display device 21 for displaying whether or not the transmission control is being performed, and when performing the transmission control, whether it is a normal system or a standby system.
A and 21B are registers 22 for storing addresses and the like.
A and 22B are provided respectively. The pair of control devices have the same address X in a predetermined communication protocol.
And the identification codes A and B unique to each device are stored in the respective registers 22A and 22B, and the control device side uses this to determine the working system / standby system and switch the system described later. Thus, the application program for controlling the devices mounted on the controller 1 is configured to transmit a data request frame to the address X and receive and process a response to the data request frame when acquiring data, for example. Control devices 2A, 2B
You do not need to be aware of which is operating as a regular system. Of course, the function of system switching control is not necessary for the application program.

FIG. 3 shows a format of an address duplication check frame (hereinafter abbreviated as ACF) which each control device broadcasts to the network when each control device starts up in the dual system. Here, it is assumed that the DeviceNet protocol is used as the communication protocol. As a feature of this DeviceNet protocol, each frame has an arbitration field consisting of 11-bit data for acquiring a bus right at the head of each frame, and when a bus right conflict occurs between stations connected to the network 3, A system that transmits a frame with a small value in the arbitration field acquires a bus right, and employs a method generally called CSMA / NBA. Each device sets its own address at a predetermined position in the arbitration field, and in the actual data section, sets an identification code consisting of a vendor ID indicating the vendor who produced and sold the device and a serial number given to the device individually. Broadcast a duplicate check frame on the network.

FIG. 4 is a diagram showing a normal system when the control device starts up.
In the flowchart of the standby system determination processing, each control device executes this. Now, it is assumed that the control device 2A has started up first. When the control device starts up, it first broadcasts the above-mentioned address duplication check frame (ACF) on the network (step 401). Thereafter, it monitors whether or not the ACF having the address X has been received from another device for a predetermined time T (steps 402 and 403). Here, the AC having the address X is received from the control device 2B or another device.
If F has not been received, the control device 2A starts operating as a dual system at time T (step 404). After becoming a normal system, if the ACF of the address X is received from another device (Yes in step 405), the AC with the address of the own station and the identification code is placed.
F is broadcast to the network (response transmission: step 406), and the operation as a normal system is continued.

When the control device 2B starts up after the control device 2A starts operating as a regular system, the control device 2B first transmits an ACF (step 401) and monitors the reception of an ACF from another device (step 401). Steps 402 and 40
3). The ACF from the control device 2B is received in step 405 of the control device 2A, and a response is transmitted (step 40).
Since 6) is performed, if T is set so that the time until this signal is received by the control device 2B is shorter than the fixed time T, the control device 2B detects the reception in step 402, and Proceed to 407. Here, the address of the received ACF is X, but since the serial number in the identification code in the received ACF matches the serial number in the identification code A of the control device 2A as the partner, the partner becomes a regular system. Is determined (Yes in step 407).
s) The operation as a standby system is started (step 408).
Thereafter, in the transmission control state as the standby system, the ACF reception check from another device and the response transmission at the time of the reception are performed (steps 409 and 410).

When the control device 2A starts up and transmits the ACF, and after the control device B starts up and transmits the ACF while monitoring the reception of the ACF from another for a fixed time T after transmitting the ACF, the control device 2A In step 402, the AC from the control device 2B having the identification code B of the control device 2B
F is detected. Therefore, in step 407, it is known from the serial number in the identification code B that the ACF is from the control device 2B, and the control device 2A becomes a standby system (step 408). On the other hand, the control device 2B does not receive the ACF from the control device 2A (starts up after it is broadcasted), and therefore, if there is no other ACF, the own station becomes the regular system (step 404).

Next, when the same address as the address X of the control devices 2A and 2B has been given to other devices,
The network is confused if they are simultaneously operating, but the flowchart of FIG. 4 also handles this. First, it is assumed that the control device 2A or 2B starts up when a device having an address X other than the control devices 2A and 2B (device 2C) is already operating as a normal system. At this time, the control device 2A or 2B receives the ACF from the control device 2C in which the address X is set as a response to its own ACF (step 40).
2) It detects that the serial number in the ACF is different from its own station and that of the other station (N in step 407).
o), an alarm indicating that there is a control device having the same address is output to the display device (step 411), and thereafter the transmission control is not performed (step 41).
2). Also, when the control device 2C starts up while the control devices 2A and 2B are operating in the normal / standby system, the control device 2C does not perform the transmission control as in the case described above. Thus, a plurality of service systems having the same address X are prevented from simultaneously entering the operating state.

In the above, the method of determining the service system / standby system at the time of startup in the control device of the present invention has been described. Next, the method of switching between the service system and the standby system of the duplexed control device will be described. The case where the control device is an input device and the case where it is an output device will be described separately. The switching here is based on the assumption that the communication function of the control device is the main cause of the failure, and specifically assumes the failure of the photoelectric converter in the case of a network using optical communication. Is known.

FIG. 5 is a diagram for explaining a method of switching between duplicated input devices, in which a controller 2A as an input device operates in a normal system and a control device 2B as an input device operates in a standby system. I do. During normal operation, the controller 1 sends a data request frame F
When the control device 2A of the ordinary system receives this, it adds the data fetched from the control target 4 to the data response frame F2 and transmits it to the controller 1. On the other hand, the standby control device 2B notifies the built-in timer 23 that the service control device 2A is transmitting and receiving the request frame F1 and the response frame F2 via the network 3.
Monitoring using B. That is, the data request frame F
The timer 23B is started by detecting 1 and the timer 23B is reset by detecting the data response frame F2. If the set time of the timer is set to be longer than the time required for the control device to receive the frame F2 and issue the frame F2, the timer is reset before the timer expires in a normal operation. However, the timer 23B
Is not reset, the control device 2B determines that the control device 2A cannot transmit the fetched data to the controller 1 due to a failure in the communication system, and sends the response frame F2 in place of the control device 2A. The data is transmitted to the controller 1 and the device itself thereafter operates as a normal system.
In addition, the cause of the expiration of the timer 23B may be simply due to the transmission delay of the frame F2 instead of the communication system failure of the control device 2A. Therefore, both the control devices 2A and 2B operate in the normal system. To prevent this, the control device 2A is connected to a station other than itself, here, the control device 2B.
Detects that the control device 2B has transmitted the frame F2 to the controller 1, determines that the control device 2B has performed the system switching, and thereafter operates itself as a standby system.

In FIG. 6, it is assumed that the output devices are duplicated, the control device 2A as the output device operates in the normal system, and the control device 2B as the output device operates in the standby system. During the normal operation, the controller 1 transmits the output data frame F3 to the device at the address X at a constant cycle. The control device 2A of the service system receives the frame F3 and outputs the data added to the frame F3 to the control target 5. The response from the control target 5 to this is transmitted to the controller 1 as a response frame F4. In order to monitor the operation of the control device 2A, a timer 24 is provided to the control devices 2A and 2B.
A and 24B are provided, and the timer 24A starts when the response frame F4 is transmitted to the controller, and resets when the output data frame F3 is received from the controller in the next cycle. Timer 2
4B starts when the output data frame F3 is detected, and is reset when the response frame F4 is detected. The set times of the timers 24A and 24B are T1 and T2, respectively.

When the timer is expired without being reset by the elapse of the set time T1 after the start of the timer 24A, the controller 2A of the service system cannot receive the frame F3 from the controller 1 due to a failure of its own communication system. Then, the data output operation to the control target 5 is stopped, and the apparatus itself thereafter operates in the standby system. When the timer 24B is started and the timer expires without being reset by the elapse of the set time T2 after the timer 24B is started, the control device 2A of the normal system becomes inactive due to a failure in the communication system. It determines that data cannot be received from the control device 1 and outputs the data of the frame F3 to the control target 5 in place of the control device 2A, and the device itself thereafter operates as a normal system.

FIG. 7 is a time chart of the above switching operation. The time T0 = t2-t1 in the figure is the time from when the controller 1 receives the response frame F4 to when the controller 1 transmits the output data frame F3 in the next cycle. Now, assuming that the communication system of the control device 2A breaks down between the times t1 and t2, the control device 2A receives the output data frame F3 from the controller 1 at the time t2, and transmits the response frame F4 at the time t3. Is not performed, the timer 24A times out after a time T1 has elapsed from the time t1. Further, the timer 24B starts counting from time t2 to T2.
After the time elapses. At this time, the control device 2A,
Since 2B does not output data to the control target 5 at the same time, T1 and T2

It is necessary to satisfy T0 + T2> T1. Further, assuming that the allowable value of the time during which no data is output to the control target 5 is T3, the time T0 + T2 from when the service system fails to return the response frame at time t1 to when the timer 24B times out is the allowable time T3.
Must be smaller. That is

## EQU2 ## T0 + T2 <T3 Here, as shown in FIG.

T4 = T3-T1 (Equation 2)

## EQU4 ## Since T0 + T2 <T1 + T4, the timer 24A is calculated from (Equation 1) and (Equation 4).
The set times T1 and T2 of 24B are

## EQU5 ## It is determined that the condition 0 <(T2-T1) + T0 <T4 is satisfied.

As described above, the switching process when a failure occurs can be executed without relying on the controller, and there is no need to change the application program of the controller for updating the system. In the above description, the DeviceNet protocol has been described as an example of the ACF. However, in other communication protocols, when the control device starts up, the control device broadcasts a frame to which the address and an identification number other than the address are added on the network. It is needless to say that similar effects can be obtained when another control device performs an appropriate reception process.

[0024]

According to the present invention, it is possible to determine the service system / standby system on the control device side and switch the system in the event of a failure without the application on the controller being conscious of the system. Since it is not necessary to change the application and to stop the system control accompanying the change of the device configuration, the change of the system configuration including the device duplication can be realized easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a control device according to the present invention.

FIG. 2 is a diagram illustrating a schematic configuration example of a system to which a transmission control method according to the present invention is applied;

FIG. 3 is a diagram showing a format of an address duplication check frame (ACF).

FIG. 4 is a flowchart showing start-up processing of a control device.

FIG. 5 is an explanatory diagram of a system switching method of an input device.

FIG. 6 is an explanatory diagram of a system switching method of an output device.

FIG. 7 is a time chart showing a frame transmission state and a timer operation state in system switching of an output device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Controller 2A, 2B Control equipment 3 Network 4 Input control object 5 Output control object 21A, 21B Display device 22A, 22B Register

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Masui, Inventor 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture F-term in the Hitachi, Ltd. Omika Plant F-term (reference) 5K032 BA08 CC09 CC10 DA01 EB06 EC01 EC03 5K048 AA06 BA23 DC01 DC04 EB01 EB11 GA06 GB08

Claims (6)

[Claims] 1. A control system comprising two control devices connected to a controller via a network, provided for each control target device, and performing data transfer processing between the corresponding control target device and the controller. A redundant transmission control method in a redundant control device, wherein the same address on the network is given to two control devices of one redundant control device, and each control device can be identified. An identification number is defined, and the identification numbers of the own device and the partner device are stored in each device of one redundant control device. When the control device is started, the address of the own device and the identification number of the own device are stored. Check the address duplication from another control device that contains the same address as the own device within a preset time after broadcasting the address duplication check frame containing When no frame is received, the operation mode of the own device is set as a normal system. After that, when an address duplication check frame having the same address as that of the own device is received from another control device, the address of the own device and the identification number of the own device are included. A duplex transmission control method characterized in that an address duplication check frame is broadcast to a network as a response. 2. An address duplication check frame including an address of the own device and an identification number of the own device is broadcast to the network when the control device is started up, and an address duplication check frame including the same address as the own device is set within the set time. Upon reception, it is checked whether or not the identification number included in the received address duplication check frame is the identification number of the control device paired with the own device, and it is the identification number of the control device paired with the own device. 2. The apparatus according to claim 1, wherein when the control device of the pair has already started up as a normal system and determined that the response has been returned, the own device enters an operation mode as a standby system.
Duplex transmission control method. 3. An address duplication check frame including the address of the own device and an identification number of the own device is broadcast to the network when the control device is started up, and an address duplication check frame including the same address as the own device is set within the set time. Upon reception, it is checked whether or not the identification number included in the received address duplication check frame is the identification number of the control device paired with the own device, and is not the identification number of the control device paired with the own device. At this time, it is determined that there is another redundant control device having the same address as the address of the redundant control device including the own device and that it is already operating, and the own device does not perform the transmission control. 2. The duplex transmission control method according to claim 1, wherein: 4. The duplex transmission control method according to claim 3, wherein when it is determined that the other duplex control device exists, an alarm to that effect is output. 5. A dual control device connected to a controller via a network, provided for each control target device, and performing a data transfer process between the corresponding control target device and the controller. A first register for storing an address on the network having the same value as a pair of control devices, and a self-device and a pair when a different identification number is given to each control device. A second register for storing an identification number of a control device, and first means for broadcasting an address duplication check frame including an address and an identification number of the own device to a network when the own device is started up. Within the preset time after the broadcast of the address duplication check frame by the A second means for outputting a reception signal when a reception frame is received, a third means for setting the own device to a normal operation mode when the reception signal is not output by this means, A fourth means for broadcasting an address duplication check frame including an identification number to the network as a response when receiving an address duplication check frame including the same address as that of the own apparatus after that; When receiving means is output by the means, it is checked whether or not the identification number included in the received address duplication check frame is the identification number of the control device paired with the own device, and the control paired with the own device is checked. Fifth means for outputting a first signal when the identification number of the device is obtained, and when the first signal is output from this means, the own device operates as a standby system. A sixth means for setting a mode, and a seventh means for preventing the apparatus from being used as a service system or a standby system when the first signal is not output from the fifth means. Control equipment characterized by the following. 6. A first display means for indicating whether the own machine is not a normal system or a standby system, and the same as the other duplex control device when startup is not performed by the seventh means. 6. An apparatus according to claim 5, further comprising at least one of second display means for indicating that an address is given.
The control device according to item 1.