JPH10145456A - Duplexing system for communication system control - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable system switching without interrupting communication control by saving information from the communication control equipment of active system into a memory area common for the active system and a reserve system each time a communication protocol starts operating, and continuing the communication control through the communication control equipment of reserve system while referring to saved information at the time of system switching. SOLUTION: A CPU 2 is internally provided with a common memory 21 and communicates with other equipment on a transmission line 0 through communication control equipment 1 connected to a common bus 3. Every communication control equipment 1 is composed of active system communication control equipment 11 and reserve system communication control equipment 12 and excepting for a system switching command for the reserve system communication control equipment 12, the CPU 2 stores the information of command and data to the communication control equipment 1 in the common memory 21 on the CPU 2 so as to hold these command and data even in case of system switching. Each time the command operation is finished, the active system communication control equipment 11 accesses the common memory 21 and fetches the information of the next command and data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplex communication control system.

[0002]

2. Description of the Related Art A dual communication control system in which two communication control devices, an active system and a standby system, are connected to one computer. A system which does not require line reconnection after switching from the active system to the standby system. Is disclosed in Japanese Patent Application Laid-Open No. 63-128839. This prior art system includes an active communication control device, a standby communication control device, and a line switching device. The active communication control device and the standby communication control device each include a transmission control circuit that interfaces with a transmission path. And a transmission control processor for controlling the same, a memory, and a failure monitoring device. When the logical connection with the other communication control device on the transmission line is completed, the active transmission control processor gives the standby transmission control processor the information necessary to hold the line, Send a connection instruction. Upon receiving the instruction, the standby transmission control processor issues a line pseudo connection command to the standby transmission control circuit, and the transmission control circuit pseudo-connects the line based on the information received by the transmission control processor. This eliminates the need for line reconnection processing when a failure occurs in the active system and the line switching device switches from the active system to the standby system.

[0003]

In the prior art, after system switching, the standby communication control device requires a command retry from the computer to resume data transmission / reception processing. However, data transmission is performed on a logical line. In this case, the frames already transmitted by the active communication control device are redundantly transmitted by the standby communication control device, and continuity of communication control cannot be guaranteed.

An object of the present invention is to provide a duplex communication control system capable of performing system switching without interrupting communication control.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a communication control apparatus of an active system which, whenever a functional unit of a communication protocol starts operating, transmits operation information of a communication protocol to a communication control apparatus common to the active and standby systems. The communication control device of the standby system refers to the save information at the time of system switching, and communication control is continued.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of a communication system in which a communication control device according to an embodiment of the present invention is duplicated.
In FIG. 1, a CPU 2 has a common memory 21 therein and communicates with other devices on a transmission line 0 via a communication control device 1 connected to a common bus 3. Each communication control device 1 includes an active communication control device 11 and a standby communication control device 12.
And are connected to the transmission line 0 and the common bus 3, respectively, and are assigned the same station address.

The CPU 2 stores command and data information common to the CPU 2 except for the system switching command for the standby communication control device, so that the command and data for the communication control device 1 can be retained at the time of system switching. The active communication control device 11 accesses the common memory 21 every time the command operation is completed, fetches the information of the next command and data, and performs the processing.

If it becomes necessary to communicate with another device,
The CPU 2 stores the active communication control device 11 in the common memory 21.
Write a logical line connection request command for The active communication control device 11 which has received the command via the common bus 3 sets a logical line connection processing flag, and exchanges information for logical line connection with other devices via the transmission line 0. When the logical line connection is completed, the logical line connection processing operation flag is cleared. After completing the logical line connection, the CPU 2
Writes the transmission request command to the active communication control device 11 and the transmission data in the common memory 21 when it becomes necessary to transmit the data to another device. The working communication control device 11 that has received the command via the common bus 3 creates a transmission frame, confirms the arrival of the frame, manages the transmission order, and transmits the frame to another communication control device on the transmission line 0. I do. At this time, the active communication control device 11 sets a flag indicating that the frame transmission process is in progress, and transmits information about the transmission operation, such as the transmission sequence number, to the CPU 2 via the common bus 3.
Write to the internal common memory 21. Upon completion of the transmission operation, the transmission processing operation flag is cleared.

Next, when data is transmitted from another communication control device, the active communication control device 11 receives the frame via the transmission line 0, and creates and transmits a response frame for confirming the incoming call. , The received frame is reported to the CPU 2 via the common bus 3. At this time, the active communication control device 11 sets a flag during the frame reception processing operation, and transmits information on the reception operation such as the transmission sequence number to the C via the common bus 3.
Write to the common memory 21 inside the PU2. When the reception operation is completed, the reception processing operation flag is cleared.

During this time, the standby communication control device 12 does nothing, but the CPU 2 monitors the active communication control device 11 via the common bus 3 at a fixed time period. When a failure is determined, a system switching command is issued to the standby communication control device 12 via the common bus 3. The standby-system communication control device 12 refers to the information written in the common memory 21 and resumes and continues the communication control from the working part of the communication control process performed by the active communication control device 11 at the time of system switching.

This operation will be described in detail below with reference to FIGS.

FIG. 2 is an explanatory diagram of the active communication control device 11. The active communication control device 11 includes an MPU 111 and an R
OM 112, RAM 113, interface circuit 1
14, a transmission control circuit 115, a modem 116, and an internal bus 117.
Are connected to the CPU 2 via the common bus 3, and the modem 116 is connected to the transmission line 0, respectively. MPU111 is ROM
It operates according to the program in 112.

After the power is turned on, the MPU 111 starts accessing the common memory 21 in the CPU 2 via the internal bus 117, the interface circuit 114, and the common bus 3. The common memory 21 stores commands from the CPU 2 to the active communication control device 11, and the MPU 1
11 accesses the shared memory again after completing the operation specified by the command.

When the CPU 2 writes a request command for logical line connection to the active communication control device 11 in the common memory 21, the MPU 111 detects this and sets a logical line connection processing operation flag in the common memory 21. Then, a logical line connection operation is started for the transmission control circuit 115 via the internal bus 117. The transmission control circuit 115 that has been activated connects the logical line on the transmission line 0 via the modem 116, and when the logical line connection operation is completed, the transmission control circuit 115 sends a completion report to the MPU 111 to the internal bus 1.
17. Thereafter, the MPU 111 registers the fact that the line is already connected in the logical line state information in the common memory 21 and drops the logical line connection operation flag.

When the CPU 2 writes a data transmission request command to the active communication control device 11 in the common memory 21, the MPU 111 detects this and sets a transmission processing operation flag in the shared memory 21 to set the common memory 21.
The transmission data written above is transferred to the RAM 11 via the common bus 3, the interface circuit 114, and the internal bus 117.
Take in 3. The MPU 111 creates a frame, adds a transmission sequence number, activates data transmission to the transmission control circuit 115, and the activated transmission control circuit 115 activates the modem 1
The frame is transmitted to the transmission line 0 via the transmission line 16. When the transmission is completed, the transmission control circuit 115 reports the transmission completion to the MPU 111 via the internal bus 117. After this, MPU11
1 saves the transmission order number to the common memory 21 via the internal bus 117, the interface circuit 114, and the common bus 3. When transmission of all data is completed, the MPU 111 clears the transmission processing operation flag in the common memory 21.

Data from another device is received by the transmission control circuit 115 via the transmission line 0 and the modem 116 and written into the RAM 111 via the internal bus 117. After the writing is completed, the transmission control circuit 115 reports the reception to the MPU 111. The MPU 111 has an internal bus 117,
The reception data report processing flag in the common memory 21 is set via the interface circuit 114 and the common bus 3, and the data in the received frame and the transmission sequence number are saved in the common memory 21. After the above operation is completed, the MPU 111
, The reception report completion is notified, and the reception data report processing flag is cleared.

When a failure occurs in the active communication control device 11, C
The standby communication control device 12 that has received the system switching command from the PU 2 via the common bus 3 refers to each operation start flag saved in the common memory 21 and communicates from the beginning of each process that was operating at the time of switching. Restart the control operation.

FIG. 3 shows information saved in the common memory 21. The operating flags 221 to 223 indicate that the logical line connection processing, the data transmission processing, and the data reception processing are in operation, respectively. The logical line status information 231 is management information on whether or not the logical line has been connected. The transmission order number 241 saves the number added to the frame at the time of the transmission activation processing, and the transmission order number 242 stores the number added to the frame at the time of the reception processing. Command activation ring 21
Reference numeral 1 denotes an information area for retaining a command and data for the communication control device 1 even at the time of system switching, and the CPU 2 sets command activation information at a location pointed to by the write pointer PP. 11 MP
U111 reads the command activation information indicated by the read pointer CP and performs communication control. The data take-in ring 212 is an information area for holding the reception data for which the reception report has been completed to the CPU 2. The MPU 111 of the active communication control device 11 sets the reception data at the position indicated by the write pointer PP. CPU2
Receives the information of the location pointed to by the read pointer CP when receiving the notification of the completion of the reception report from the MPU 111. The update of the write pointer PP, the read pointer CP, and the ring flags PF, CF is performed according to the flow of FIG.

In FIG. 5, instead of the CPU having a common memory area for the active communication control device and the standby communication control device, the active communication control device communicates at the start of each function of the communication protocol processing. A method of writing the protocol operation information to the memory area of the communication control device of the standby system will be described. Like the active communication control device 11, the standby communication control device 12 includes an MPU 121, a ROM 122,
An AM 123 and an interface circuit 124 are provided. The interface circuit 124 is connected to the active communication control device 11 via the common bus 3. MPU121 is ROM1
It operates according to the program in 22. The RAM 113 and the RAM 123 in the active and standby communication control devices have the save information, command start ring, and data take-in ring shown in FIG.

At the time of command activation, the CPU 2 sets the command activation information in the command activation ring of the RAM 113 in the active communication control device 11 and also transmits the command activation information to the command activation ring of the RAM 123 in the standby communication control device 12. Set. The active communication control device 11 reads the command activation information from the command activation ring of the RAM 113 at the time of executing the command, and after completing the command operation, updates the CP of the activation ring by +1 and at the same time simultaneously executes the command activation ring of the RAM 123 of the standby communication control device 12. Is updated by +1 via the common bus 3. Also,
The save information such as the transmission order number is saved to the RAM 123 of the standby communication control device 12 via the common bus 3.

[0021]

According to the present invention, it is possible to provide a duplex communication control system capable of performing system switching without interrupting communication control.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a system according to the present invention.

FIG. 2 is an explanatory diagram of an active communication control device.

FIG. 3 is an explanatory diagram of information on a common memory.

FIG. 4 is a flowchart of a command ring operation.

FIG. 5 is an explanatory diagram of an information evacuation method from an active system to a standby system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Communication control apparatus, 2 ... CPU, 3 ... Common bus, 11 ...
Active communication control device, 12 ... Standby communication control device, 21
... Common memory.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideaki Mashiko 5-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside the Omika Plant, Hitachi, Ltd. (72) Inventor Naoo Ogawa 5-chome, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Hitachi, Ltd. Omika Plant (72) Inventor Akira Yamakoshi 5-2-1 Omika-cho, Hitachi City, Ibaraki Pref.

Claims (5)

[Claims] A plurality of nodes are connected to one or a plurality of communication lines, and each node comprises a CPU, an active communication control device, and a standby communication control device.
When U communicates with another CPU on the communication line, the CPU normally communicates with the other CPU on the communication line via the working communication control device, and In a redundant communication control system that switches to the standby communication control device and performs communication when the control device fails, the active and standby communication control devices receive commands and data from the CPU. The function of connecting a logical line to another communication control device, creating and transmitting a frame, and receiving a frame from a transmission line
It has a communication protocol for transmitting a report to the CPU and transmitting a response frame to the communication control device of the transmission source, exchanges a frame with the other communication control device, and the communication control device of the working system, The standby system has means for storing commands and data from the CPU in a location that can be commonly accessed by the communication control device, and means for storing operating state information of the communication protocol processing. The standby system stores the information stored by the active system By starting the communication protocol processing in the middle based on the above, when a failure occurs in the active communication control device and switches to the standby system, the standby system restarts the processing from the point where the communication protocol was interrupted. And a communication control device duplex system wherein communication can be continued without interruption as a whole node. 2. The communication protocol according to claim 1, wherein:
Divided into functional units such as command processing from the CPU, connection establishment with the other communication control device, data transmission and frame order management, and reporting of received data to the CPU. Each function stores, as operation information of the communication protocol processing, a flag indicating that the function is operating at the start of the operation, a connection state with another communication control device, and a sequence number of a transmission / reception frame. A redundant communication control system for starting the communication protocol processing from the beginning of the functional unit operating in the active system at the time of system switching. 3. The method according to claim 1, wherein command and data information is stored in a memory on said CPU as means for storing commands and data from said CPU, and said communication control device stores said command and data each time a command operation is completed. A redundant communication control system that accesses and accesses commands and data. 4. The communication control device according to claim 1, wherein said CPU has a memory area common to said active communication control device and said standby communication control device as means for storing operation status information of said communication protocol processing. Duplex system. 5. A communication system according to claim 1, wherein said means for storing the operation state information of said communication protocol processing includes a memory area common to said active communication control device and said standby communication control device. A redundant communication control system in which the active communication control device writes operation information of the communication protocol into a memory area of the standby communication control device when each function of the communication protocol processing starts.