JP3380957B2 - Redundant communication controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device used for fieldbus communication, and more particularly to a dual communication control device capable of duplex communication.

[0002]

2. Description of the Related Art Conventionally, in order to control a plant or the like,
It was done by analog transmission. However, in recent years, digital transmission has been required for communication between the control device and the field device, and the transmission method is being standardized. This transmission is called a fieldbus. This fieldbus is described in "Fieldbus Basic Book", Tadada Kai Kai, Ohmsha, etc.

The specifications of the above field bus are determined as follows. 1) A plurality of field devices are connected on a pair of electric wires. 2) Communication between the field devices and between the host (control device) and the field device is controlled by the LAS (link active scheduler) function. 3) The LAS is determined from the LM (link master) device on the fieldbus according to the procedure defined by the standard.

The LAS is generally executed by an interface device with the host. Since LAS controls all fieldbus communications, high reliability is required for the interface device on which it is executed.

Here, the fieldbus communication control section roughly includes the following two functions. 1) A function of transferring cascade data (control data) between the functional blocks of the control device and the functional blocks of the field device. 2) A function to transfer the data acquisition and data setting request for the internal parameter of the functional block of the field device from the operator's station.

Such a device is shown in FIG. In the figure, 1 is an operator's station (OPS), which has an operator's operation panel and a CRT. A control station (FCS) 2 is provided with a plurality of stations and is operated by the OPS 1. 3 is a fieldbus communication control device, F
It is connected to CS2 via an internal communication bus to control the communication of the fieldbus 4 and to interface the FCS2 to the field device 5 connected to the fieldbus. Here, the field device 5 indicates, for example, a sensor, a valve, or the like.

The fieldbus communication control device 3 will be described in more detail with reference to FIG. In the figure, 31 is a host interface processing means, which receives communication data from the FCS 2 and receives communication data from the fieldbus 4 by F
Send to CS2. A fieldbus protocol processing unit 32 processes the communication data received by the host interface processing unit 31 into the fieldbus protocol and processes the communication data from the fieldbus 4 from the fieldbus protocol. A LAS processing unit 33 controls communication on the fieldbus 4. Specifically, the communication authority is sequentially given to each device. Reference numeral 34 denotes a transmission / reception circuit, which receives the communication frame from the fieldbus 4 and also the fieldbus protocol processing means 32.
The data is received from and transmitted to the fieldbus 4.
The transmission / reception circuit 34 also transmits a communication frame from the LAS processing means 33, which gives the communication authority, to the field bus 4. An address filtering processing unit 35 receives a communication frame received by the transmission circuit 34, and when the communication frame is a data frame or an address addressed to itself,
The communication frame is transmitted to the fieldbus protocol processing means 32.

The operation of such a device will be described below.
The LAS processing means 33 outputs to the transmission / reception circuit 34 a communication frame composed of an address corresponding to each device and a communication authority in an order defined by the standard for all devices including itself connected to the fieldbus 4. To do. The transmission / reception circuit 34 transmits this communication frame to the field bus 4.

If the address is addressed to itself, the transmission / reception circuit 34 receives this communication frame from the field bus 4 and sends it to the address filtering processing means 35. The address filtering processing means 35 sends it to the field protocol processing means 32 because it is an address addressed to itself.

At this time, the FCS 2 has already transmitted the control data for the field device 5 and the address of the field device 5 to be controlled to the host interface processing means 31. The host interface processing means 31 processes this data by the fieldbus protocol processing means 32.
Send to.

Since the fieldbus protocol processing means 32 has been given the communication authority by the LAS processing means 33, the protocol processing is performed on the communication data from the host interface means 31, and the address of the fieldbus communication control device 3 is set. Is added to send a communication frame to the transmission / reception circuit 34. The communication frame created here is
It consists of control information (frame type), destination address, source address, parameters, application layer data, and additional data for error detection. The transmission / reception circuit 34 transmits the received communication frame to the field bus 4. Then, the field device 5 performs control only when the destination is the address addressed to itself and the source address is the address stored inside the local station, that is, the address of the fieldbus communication control device 3 matches. Data is written and processing corresponding to the control data is executed.

When the field device 5 receives the communication authority from the LAS processing means 33, the field device 5 adds its own address as the source address to the data to be transmitted to create a communication frame, and transmits the communication frame to the field bus 4. To do.

Then, the transmission / reception circuit 34 receives this communication frame and sends it to the address filtering processing means 35. Since the communication frame is a data frame, the address filtering processing means 35 sends the communication frame to the fieldbus protocol processing means 32. The fieldbus protocol processing means 32 performs protocol processing on the communication frame and sends the communication data to the host interface processing means 31. The host interface processing means 31 sends communication data to the FCS2.

[0014]

Duplication of communication is essential for process applications that require high reliability. However, as a fieldbus specification, which is an open network protocol, LAS to another device when the LAS function stops due to some factor
The transfer procedure is specified, but for the following reasons,
It was difficult to duplicate the fieldbus communication controller.

1) On the fieldbus, each device is assigned a unique address. As for the control data transmitted to the field device, only the communication frame from the predetermined address is permitted to be written in the field device. That is, the field device accepts communication only from the determined device.

2) Since the fieldbus 4 is an open protocol, it is not possible to add a unique protocol to solve the above.

Therefore, an object of the present invention is to realize a fieldbus communication control device capable of duplicating communication without adding a unique protocol.

[0018]

SUMMARY OF THE INVENTION The present invention is a duplicated communication control device for communicating with a field device which is connected to a field bus and permits only control data from a specific address to be written. The specific
The control side fieldbus communication control unit that communicates by address and the address different from this control side fieldbus communication control unit.
When the control side fieldbus communication control section is unable to communicate, the address of the control side fieldbus communication control section is added to the communication frame as the source address to create a communication frame, which is then added to the fieldbus. And a standby side fieldbus communication control section for transmitting and receiving a communication frame on the fieldbus by using the address of the control side fieldbus communication control section as its own address.

In the present invention as described above, the control side field communication control section normally communicates with the field device. When the control-side field communication unit cannot communicate, the standby-side fieldbus communication control unit adds the address of the control-side fieldbus communication control unit to the communication frame as a source address to create a communication frame, Send to. Further, the standby side field communication control unit receives the communication frame on the fieldbus with the address of the control side fieldbus communication control unit as its own address.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. 7 that are the same as those in FIG.

Reference numeral 6 is a standby side fieldbus communication control unit,
When the fieldbus communication control unit 3 cannot communicate, the address of the fieldbus communication control unit 3 is added to the communication frame as a source address to create a communication frame, and the communication frame is transmitted to the fieldbus 4. Then, the standby side fieldbus communication control unit 6 receives the communication frame on the fieldbus 4 with the address of the fieldbus communication control unit 3 as its own address.

A specific configuration of the standby side fieldbus communication control unit 6 will be described below with reference to FIG. A host interface processing unit 61 receives communication data from the FCS 2 and sends the communication data from the fieldbus 4 to the FCS 2. A fieldbus protocol processing unit 62 adds the address of the fieldbus communication control unit 3 as a source address to the communication data from the host interface processing unit 61 to create a communication frame, and also transmits the communication data from the fieldbus 4 to the communication data. Fieldbus protocol processing is performed and communication data is sent to the host interface processing means 61. Reference numeral 63 is a LAS processing means for monitoring the operation of each device on the fieldbus 4,
If the LAS processing means 33 is not operating, LA
Instead of the S processing means 33, communication control of the fieldbus 4 is performed. Specifically, the communication authority is sequentially given to each device. The operation confirmation and switching of other LAS processing means are determined by the fieldbus specifications. Reference numeral 64 denotes a transmission / reception circuit, which is connected to the fieldbus 4 to exchange data with the fieldbus protocol processing means 62 and to receive and transmit a signal from the LAS processing unit 63. 6
Reference numeral 5 is a status display processing means, and LAS processing means 63 is
It is detected whether or not it is in operation, and the state holding means 66 holds it. Reference numeral 67 is a duplication storage means for storing whether or not duplication is performed. An address filtering processing unit 68 receives a communication frame received by the transmission / reception circuit 64, and a communication frame for requesting transmission from the fieldbus 4 to its own address and an address of the fieldbus communication control unit 3 and a data communication frame. To the fieldbus protocol processing means 62.

The operation of such a device will be described below.
First, the receiving operation will be described. FIG. 3 is a flowchart showing the operation of the address filtering processing means 68. FIG. 4 is a flow chart showing the receiving operation of the host interface processing means 61.

The transmitting / receiving circuit 64 receives the communication frame from the field bus 4 and sends the communication frame to the address filtering processing means 68. It is confirmed whether the communication frame is a data communication frame or a transmission request communication frame addressed to itself (S1).

In the case of a data communication frame or a communication frame of a transmission request addressed to itself, the communication frame is sent to the fieldbus protocol processing means 62 (S5).

If the frame is not a data communication frame or a communication frame of a transmission request addressed to itself, it is confirmed whether or not duplexing is in progress (S2).

When the duplication is in progress, the state holding means 66 confirms whether or not the LAS processing means 63 is operating. If it is operating, it is confirmed whether the communication frame matches the address of the control side fieldbus communication control unit 3 (S4). If they match, the communication frame is sent to the fieldbus protocol processing means 62 (S5). If they do not match, the communication frame is discarded (S6). If it is not duplexing, the communication frame is discarded (S6).

The fieldbus protocol means 62 protocol-processes the communication frame received from the address filtering processing means 68.

Then, the host interface processing means 61 determines whether or not it is duplicated by the duplicated storage means 6.
Confirm by 7 (S1).

When the LAS is duplicated, the operating state indicating whether the LAS is operating is received from the state holding means 66,
It is added to the communication data received from the fieldbus protocol processing means 62 (S2). Then, the added data is sent to the internal communication bus (S3).

If not duplicated, the communication data received from the fieldbus protocol processing is sent to the internal communication bus (S3).

Next, the transmission operation will be described. FIG. 5 is a flowchart showing the transmission operation of the host interface processing means 61.

The host interface processing means 61 is
It is confirmed by the duplicated storage means 67 whether or not it is duplicated (S1).

In case of duplication, LAS processing means 6
The state holding means 66 confirms whether or not 3 is in operation (S2). When the LAS is operating, the communication data from the FCS2 is sent to the fieldbus protocol processing means 62 (S3). If the LAS operation is not in progress, the process ends.

When the communication data from the FCS2 is not duplicated, the fieldbus protocol processing means 62 is used.
To (S3).

Then, the fieldbus protocol processing means 62 performs protocol processing on the communication data and sends it to the transmission circuit 64. Then, the transmission circuit 64 performs a transmission operation.

In this way, when the control side fieldbus communication control section 3 becomes unable to communicate, the standby side fieldbus communication control section 6 adds the address of the control side fieldbus communication section 3 at the time of transmission to The communication frame is transmitted to the device 5. Then, at the time of reception, it receives the communication frame of the transmission request of the address of the control side fieldbus communication unit 3 and the address addressed to itself. As a result, even when the field device 5 receives a communication frame having only a fixed transmission source address, the communication can be duplicated.

Since the fieldbus communication control units 3 and 6 are provided with the LAS processing means 33 and 63, respectively, the LAS processing means 63 is always operated by the other LAS processing means 3.
In order to monitor 3, the control side fieldbus communication control unit 3
You can instantly know that you can no longer communicate. That is, even if the control side fieldbus communication control section 3 cannot communicate, the standby side fieldbus communication control section 6 can immediately take the place.

Next, another embodiment will be described with reference to FIG. 7 that are the same as those in FIG. In the figure, 7 is a LAS processing unit that monitors the operation of each device on the fieldbus and
Communication control. Specifically, the communication authority is sequentially given to each device.

Reference numeral 8 is a control side fieldbus communication control section,
It communicates with the field device 5 on the field bus 4.
The difference from the fieldbus communication control unit 3 of FIG.
This is that the S processing unit 33 is not executed.

Reference numeral 9 is a standby side fieldbus communication control unit,
It has a monitoring means 91 and a live list 92, and when the control side fieldbus communication control section 8 is inactive in the live list 92, the address of the control side fieldbus communication control section 8 is added to the communication frame as a source address. Then, a communication frame is created and transmitted to the fieldbus 4, and the communication frame on the fieldbus 4 is received with the address of the control side fieldbus communication controller 8 as its own address. Then, the monitoring unit 91 monitors the operation monitoring signal of each device on the fieldbus 4 by the LAS processing unit 7, and describes in the live list 92 whether each device is currently operating.

The operation of such a device will be described below.
The LAS processing unit 7 gives communication authority to each device on the fieldbus 4. Then, the LAS processing unit 7 communicates with each device at regular intervals and confirms whether each device is operating. The monitoring means 91 monitors this signal and describes in the live list 92 whether or not each device is operating.

The standby side fieldbus communication control section 9 confirms whether the control side fieldbus communication control section 8 of the live list 92 is operating. If it is in operation, nothing is done. If it is not operating, the standby side fieldbus communication control unit 9 starts the operation, and when transmitting, the address of the control side fieldbus communication control unit 8 is added to the communication frame as a source address to create a communication frame. , Fieldbus 4. When receiving, a communication frame on the fieldbus 4 is received with the address of the control side fieldbus communication control unit 8 as its own address.
When receiving, if the communication frame is data, the data will be transmitted by broadcast,
The standby side fieldbus communication control unit 9 receives it.

[0044]

The present invention has the following effects. According to claims 1 to 4, when the control-side fieldbus communication unit cannot communicate, the standby-side fieldbus communication control unit adds the address of the control-side fieldbus communication unit at the time of transmission and adds the address to the field device. Send a communication frame. Then, at the time of reception, the communication frame is received with the address of the control side fieldbus communication unit as its own address. As a result, even if the field device receives a communication frame having only a fixed transmission source address, the communication can be duplicated.

According to claim 3, since the LAS processing means is provided in each of the control side and the standby side fieldbus communication control section, the LAS processing means constantly monitors the other LAS processing means. You can instantly know that the fieldbus communication control unit has lost communication. That is, even if the control-side fieldbus communication control unit cannot communicate, the standby-side fieldbus communication control unit can immediately take over.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration of a standby side fieldbus communication control unit 6.

FIG. 3 is a flowchart showing the operation of address filtering processing means 68.

FIG. 4 is a flowchart showing a receiving operation of a host interface processing means 61.

5 is a flowchart showing a transmission operation of a host interface processing means 61. FIG.

FIG. 6 is a configuration diagram showing another embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional communication control device.

FIG. 8 is a diagram showing a specific configuration of a fieldbus communication control unit 3.

[Explanation of symbols]

3 Fieldbus communication controller 4 fieldbus 5 field devices 6 Standby side fieldbus communication controller 7 LAS processing unit 8 Control side fieldbus communication controller 9 Standby side fieldbus communication controller 61 Host interface processing means 62 Fieldbus protocol processing means 63 LAS processing means 64 transmitter / receiver circuit 68 Address filtering processing means 91 Monitoring means 92 Live List

Claims (6)

(57) [Claims] 1. A duplicated communication control device connected to a field bus and communicating with a field device which permits writing of control data only from a specific address, the control being for communicating with the field device at the specific address. Side fieldbus communication control unit and an address different from this control side fieldbus communication control unit
Is added, and when the control side fieldbus communication control section cannot communicate, the address of the control side fieldbus communication control section is added to the communication frame as a source address to create a communication frame and sent to the fieldbus. Then
A duplex communication control device, comprising: a standby-side fieldbus communication control unit that receives a communication frame on a fieldbus with the address of the control-side fieldbus communication control unit as its own address. 2. A duplicated communication control device which is connected to a field bus and communicates by broadcast with a field device which permits writing of control data only from a specific address, and which communicates with the field device at the specific address. The control side fieldbus communication control part to perform and the address different from this control side fieldbus communication control part
Is added, and when the control side fieldbus communication control section cannot communicate, the address of the control side fieldbus communication control section is added to the communication frame as a source address to create a communication frame and sent to the fieldbus. Then
A duplex communication control device, comprising: a standby-side fieldbus communication control unit that receives a communication frame on a fieldbus with the address of the control-side fieldbus communication control unit as its own address. 3. A specific ad connected to a fieldbus.
A duplex communication control device that communicates with a field device that allows writing only in a communication frame broadcast by a broadcast , and a control side fieldbus communication control unit that communicates with the field device at the specific address, and this control side. Address different from fieldbus communication controller
Is added, and when the control side fieldbus communication control section cannot communicate, the address of the control side fieldbus communication control section is added to the communication frame as a source address to create a communication frame and sent to the fieldbus. Then
A duplex communication control device, comprising: a standby-side fieldbus communication control unit that receives a communication frame on a fieldbus with the address of the control-side fieldbus communication control unit as its own address. 4. A specific add connected to a fieldbus.
Response that allows writing only to the control data from
A redundant communication control device for communicating with a field device, and a device for communicating with the field device at the specific address.
Communication cannot be performed between the local side fieldbus communication control unit and this side fieldbus communication control unit.
The communication side, the control side fieldbus communication will be added to the communication frame.
The address of the communication control unit is added as the source address
Signal frame, send to fieldbus, control side
Enter the address of the fieldbus communication control unit to yourself.
Waiting to receive a communication frame on the fieldbus
The standby side fieldbus communication control section has a machine side fieldbus communication control section, and the standby side fieldbus communication control section has a host interface processing means for communicating with the host device, and a transmitting and receiving circuit for connecting with the fieldbus and transmitting and receiving communication frames. receiving a communication frame transmitting and receiving circuit receives, through
The destination address of the received frame is the address addressed to itself and the control side
At the address of the fieldbus communication control unit, an address filtering processing unit that processes as a communication frame addressed to itself, receives the communication frame from this address filtering processing unit, performs protocol processing, and controls the data from the interface processing unit. 2. The duplex communication control device according to claim 1, further comprising a fieldbus protocol processing means for creating a communication frame by adding the address of the side fieldbus communication control unit as a source address and sending the communication frame to the transmitting / receiving circuit. . 5. The control side fieldbus communication control section and the standby side fieldbus communication control section are respectively provided with link active scheduler processing means, and when the control side field communication control section becomes unable to communicate, standby by switching to the link active scheduler processing means side fieldbus communication controller, duplex communication control device according to any one of claims 1 to 4, characterized in that the switched communications to the stand-by side fieldbus communication controller . 6. waiter Fieldbus communication control unit according to claim, characterized in that the live list the operating state of each device on the field bus is described, switching from the control side fieldbus communication controller 1-4 The duplicated communication control device described in any one of 1 .