JPH07210518A - Time synchronizing system for distributed processing system - Google Patents

Abstract

PURPOSE:To normally synchronize time even when any one of processors inside a distributed processing system is stopped by synchronizing the time between the respective processors of the system while considering transmission delay time. CONSTITUTION:In the time synchronizing system for distributed processing system, the synchronization of time is executed while considering the delay time of transmission by providing a function for transmitting time information onto a transmission line in a fixed cycle and a function for correcting time managing information inside a processor 11 corresponding to the time information possessed from the transmission line and the time of transmission up to the time information transmitting processor at each processor 11 at the distributed processing system composed of the transmission line and the plural processors 11 connected to that common transmission line by a transmission controller. Thus, the stable synchronization is enabled regardless of the length of the transmission line. At the same time, the synchronization of time is enabled regardless of the start/stop of any specified processor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network, and more particularly to a time synchronization method suitable for an application system of a distributed processing system.

[0002]

2. Description of the Related Art In the prior art, as described in Japanese Patent Laid-Open No. 63-14214, time information is transmitted from a specific processing device at a constant cycle, and when another processing device on the transmission line receives the time information. Then, the time was synchronized. However, there is a problem that the transmission delay time is not taken into consideration, and there is a problem that an error occurs in the time synchronization time. Also, because a special time management means is provided, if the means disappears due to the stop of the processing device, etc. There was a problem that was not synchronized.

[0003]

When the time is not synchronized between the processing devices, or when the transmission time is measured between the two processing devices on the transmission path, the data transmission time and the data reception between the two processing devices are performed. The transmission time is calculated from the time difference,
If the synchronization times are different, the data reception time is earlier than the data transmission time, and there is a possibility that a negative transmission time can be obtained.

In the above-mentioned prior art, in order to solve the above problems,
There were the following problems.

1. Since the transmission time between processing devices is not taken into consideration, if the transmission path becomes long, the transmission delay time will cause
The synchronization time does not match between the processors.

2. Since a dedicated processing device for time synchronization exists, time synchronization is not performed when the processing device stops.

3. Since the time is synchronized in a cycle,
If there is a processing device that has been stopped and then restored on the transmission line,
The synchronization of the time to the processing device must wait for the next cycle.

An object of the present invention is to solve the above problems and provide a highly reliable time synchronization method in a distributed processing system.

[0009]

The above object is realized by the following means.

1. It is impossible for the processing devices themselves to measure the transmission time between the processing devices on the transmission line because it is premised that the times of the plurality of processing devices are synchronized. Therefore, the transmission time between each processing device is measured in advance and recorded in the processing device. The internal time is calibrated by adding the measured transmission time to the transmission time of the information for time synchronization to make it the current time.

2. For time synchronization, all the processing devices manage the time without providing a dedicated processing device. However, not all the processing devices can be the time management processing device, and therefore the processing devices are given an order in which they should be the time management processing device. The time management processing device should be prioritized by those having a highly accurate clock and those having a light load in the network. Of the processing devices operating in the network, the one having the highest rank is the processing device that manages the time.

[0012]

[Action]

1. If all the processing devices on the transmission line are operating normally, among the processing devices on the transmission line that have a relatively accurate internal clock, select the one with a relatively light load and set the time for the entire network. Defined as the processing device to manage. A processing device that manages time broadcasts time information for time synchronization on a transmission path at regular intervals. Other processing devices take this information into each processing device from the transmission path, add the transmission time to the processing device that manages the time to make it the current time, and calibrate the internal clock to synchronize the time. Done.

2. When a processing device that manages the time of the entire network is defined, if a processing device other than the processing device that manages the time stops and then starts operating again, the processing device that manages the time of the entire network stops operating. Send time information for time synchronization to the started processing device,
Time synchronization is performed.

3. When the processing device that manages the time of the entire network is defined and the processing device that manages the time of the entire network stops, the processing device with the highest priority among the processing devices operating in the network Manages the time of the entire network.

[0015]

EXAMPLE An example of the present invention will be specifically described below.

First, the configuration of the distributed processing system to which the present invention is applied will be described with reference to FIGS.

FIG. 2 is a diagram showing the overall configuration of a system to which the present invention is applied. In the figure, 11 to 14 are
A processor 31 stores an application program in its internal memory and executes the application program. Reference numeral 31 denotes a unidirectional loop transmission line in the arrow direction. Reference numerals 21 to 24 are transmission control devices that perform data exchange control between the processing devices 11 to 14 and the transmission path 31. The processing results of the processing devices 11 to 14 are transmitted as a message from the transmission control devices 21 to 2
It is transmitted to the transmission line 31 via 4. Each transmission controller
Whether or not the message on the transmission line 31 is necessary for the processing device connected to the transmission control device of the accident is judged by looking at the code indicating the content of the data called the function code added to the message, and judged as necessary. Send only the specified message to the processing device connected to itself. Each processing device 11
From No. 14 to No. 14, the received message is used to execute the processing of the predetermined program, and the result of the execution and the function code are output as a message.

FIG. 3 shows a format example of a message flowing through the transmission line. In the figure, FC201 is a function code, which is a code corresponding to data and a function.
SA202 is the address of the transmission control device that generated the message, and CC203 is a serial number that is necessary for transmission control. The sender processing device number indicates the processing device number of each processing device that has transmitted the message, and the DATA 204 indicates the content of the processing result of each application program. Further, the FCS 205 is for error detection data,
F200 and 206 are flags indicating the beginning and end of the message, respectively. Each transmission control device receives the FC sent from the processing device, the source processing device number, and DATA.
A message is created and transmitted in the message format shown in FIG. 3 based on the format. Also, it takes in a message on the transmission line necessary for the processing device connected to itself and sends a message composed of FC, the source processing device number and DATA to each processing device.

FIG. 1 is a diagram showing an example of the configuration of the present invention, and illustrates a portion necessary for time synchronization in the internal configuration of the processing device 11 of FIG.

The processing units 12, 13 and 14 also have the same structure inside. The time information transmission process 1 is a process of transmitting time synchronization information to the transmission path when the self processing device is a processing device that manages the time of the entire network (hereinafter referred to as a master processing device). Time information reception process 2
Is a process of receiving the information for time synchronization, calibrating the internal clock with the time obtained by adding the transmission delay time to the time in the received information as the current time. Reference numeral 3 is a file (hereinafter referred to as a time management order file) that records the order to be the master processing apparatus of each processing apparatus on the transmission path and the operating status / stoppage of the processing apparatus. It is determined from the information whether the self-processing device is the master processing device. Reference numeral 4 denotes a file in which the transmission time to another processing device on the transmission path is recorded (hereinafter referred to as a transmission time file). The time information reception processing 2 uses the transmission delay time from this file when synchronizing the times. Ask. 5 is an internal clock, 6
Is a survival monitoring function. Reference numeral 7 is a file that records whether the processing device on the transmission path is operating or stopped.

The survival monitoring function 6 broadcasts the information of its own processing device on the transmission line in a short cycle of about several seconds. Further, it is a function for knowing that another processing device on the transmission path is in operation by receiving similar information from another processing device. When this information cannot be received continuously for several cycles, the corresponding processing device determines that it is stopped. Whether the processing device is operating or stopped is recorded in a file 7.

Reference numeral 101 denotes an arrow for transmitting time information for time synchronization from the time information transmitting process 1, 102 denotes an arrow for periodically activating the time information transmitting process 2 and fetching time information, 103.
Is an arrow indicating that the time information reception process 3 receives the time information for time synchronization, and 104 is the internal clock 6 by the time information reception process.
Of the calibration, 105 is an arrow for taking in the master order, 106 is an arrow for updating the flag of the operating / stopping of each processing device, 107 is an arrow for acquiring the transmission time by the time information reception processing 3, and 108 is The arrow for updating the file 7 for recording the operating / stopping of the processing device on the transmission path by the survival monitoring function 6 and the arrow 109 for monitoring the operating / stopping of the processing device on the transmission path by the time information transmission processing. .

Prior to the description of the operation of this embodiment, the structure of the time management order file 3 and the transmission time file 4 used in this embodiment and the format of the time information for time synchronization are shown in FIGS. It demonstrates using.

FIG. 4 shows the structure of the time management order file 4 shown in FIG. In this file, the numbers of the processing devices are arranged in the order of priority to be the master processing device, and each processing device includes a flag indicating whether the processing device is operating / stopped and a master processing device flag. As for the priority order of the master processing device, the one having a high accuracy according to the specifications of the internal clock 6 and the one having a relatively light load in the network are set to the high order to determine the order. The priority order of the master processing devices in this file is common to all the processing devices in the network. The flag indicating whether the processing device is in operation / stopped is one that the time information transmission process 1 checks and updates what is detected by the survival monitoring function 6.
The master processor flag is a flag indicating the current master processor. However, a processing device in which the accuracy of the internal clock 6 is extremely poor is marked from the beginning so as not to be a master processing device.

FIG. 5 shows the structure of the transmission time file 5 of FIG. This file is constructed by arranging the transmission times between its own processing device and other processing devices in the order of the processing device numbers.
The transmission time between its own processing device and another processing device is the average value measured several times in advance, plus the processing time from the reception of the time information in the time information reception process 2 to the calibration of the internal clock 6. This file is for reference only and is not rewritten.

FIG. 6 shows a format example of time information for time synchronization. Reference numeral 204 denotes a DATA part in the format example of the message shown in FIG. This format is used as time information for time synchronization (hereinafter referred to as time synchronization information) in combination with FIG. 3 described above. Reference numeral 41 indicates a processing device number that transmits the time synchronization information, 42 indicates a processing device number that receives the time synchronization information, and 43 indicates a transmission time of the time synchronization information.

Next, the progress of time synchronization in this embodiment will be described with reference to FIGS.

First, FIG. 2 shows time synchronization in a normal time. In this example, the processing device 11 is the master processing device according to the priority order to be the master processing device. The time information transmission process 1 of the processing device 11 is activated at regular intervals by the internal clock 5, and the processing device number 41 for transmitting the time synchronization information to the processing device number of its own processing device and the processing device number 42 for receiving the time synchronization information. 0, and the current time is edited from the internal clock 5 at the time of transmission 43 of the time synchronization information to obtain the time synchronization information, which is broadcast to the transmission line. Processor 12, 13,
In the time information reception process 2 of 14, the time synchronization information broadcast by the processing device 11 is received from the transmission path. Processing device number 41 for transmitting the time synchronization information in the received time synchronization information
Then, the transmission delay time is obtained from the transmission time file 4, the transmission delay time is added to the transmission time 43 of the time synchronization information to obtain the current time, and the internal clock 5 is calibrated.

Next, with reference to FIG. 7, the time synchronization when the processing device is stopped and when the processing device on the transmission path is started is shown. In the figure, the order of becoming the master processing device of each processing device is determined so as to be within the frame of the processing devices 11 to 14.
Further, the processing device 12 cannot be a master processing device.

As in the case of FIG. 2, when the processing device 11 is the master processing device and the processing device is stopped, it is detected by the survival monitoring function 6 of the processing devices 12, 13, and 14. In the time information transmission process 1, the processing device 13 having the highest rank as the master processing device among the processing devices in operation due to the stop of the processing device 11 is determined as the next master processing device. When the time information 1 of the processing device 13 that has become the master processing device is activated by the internal clock 5 in a fixed cycle, the time synchronization information is edited in the same way as when the processing device 11 described above is the master processing device, Broadcast to. Processor 1
In the time information reception processing 2 of 2 and 14, the internal clock 5 is similarly calibrated. In this case, the processing device number 41 that transmits the time synchronization information in the time synchronization information becomes the processing device number of the processing device 13 and is obtained by the processing devices 12 and 14. The transmission delay time also depends on the processing device 13. After this, the processing device 1
When 1 starts the operation, the time information transmission process 1 of the processing device 11 first searches the processing devices other than the own processing device for the master processing device. The processing device 13 determines that it is the master processing device based on the operating / stopped states of the processing devices other than the self processing device. Since the processing device 13 detects the start of operation of the processing device 11 by the survival monitoring function 5, the processing device 13 transmits the time synchronization information in which the processing device number of the processing device 11 is edited to the processing device number 42 which receives the time synchronization information, and the processing device 13 The time of 11 is synchronized.

In the case where all the processing devices are stopped and the processing devices 12, 13, 14, 11 are started in this order in FIG. 7, when the processing device 12 starts operating, the processing device 12 is started.
Cannot be a master processor, so nothing happens. When the processing device 13 starts operating, it becomes the master processing device because the master processing device is not in the network, and the time is synchronized with the processing device 12. After that, when the processing devices 14 and 11 start operating, the processing device 13 is the master, so that the processing device 13 synchronizes the time.

[0032]

The effects of the present invention are as follows.

1. Stable synchronization can be performed regardless of the length of the transmission path.

2. The time can be synchronized regardless of whether the specific processing device is operating or stopped.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of components in an embodiment of the present invention.

FIG. 2 is a configuration diagram of a network to which the present invention is applied.

FIG. 3 is a format of data flowing on a transmission path.

FIG. 4 is a schematic configuration diagram of a file that records the order and life and death that should be the master processing device of each processing device.

FIG. 5 is a schematic configuration diagram of a file that stores a transmission time to each processing device.

FIG. 6 is a format of transmission data in the embodiment of the present invention.

FIG. 7 is a diagram showing a ranking of processing devices according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Time information transmitting process, 2 ... Time information receiving process, 3 ... Management of each processing device
File for recording stoppage, 4 ... File for recording transmission time to other processing device, 5 ... Internal clock, 6 ... Survival monitoring function, 7 ... File for storing operating / stopping of other processing device, 11 to 11 14 ... Processing device, 21-24 ... Transmission control device, 31 ... Transmission path, 41 ... Time information transmission processing device number, 42 ... Time information receiving processing device number, 43 ... Time synchronization information transmission time, 101 ... Time Arrow for transmitting time information at the time of synchronization, 102 ... Arrow for activating the time information transmission process 2 and arrow for fetching the time information, 103 ... Arrow for receiving the time information at the time synchronization, 104 ... Arrow for calibrating the internal clock 6. , 105 ... Arrow for capturing master order, 106 ...
An arrow for updating the time management priority file 4 due to the operation / stop of another processing device, 107 ... An arrow for fetching the transmission time from the file 4 storing the transmission time to the other processing device,
108 ... Arrow for updating a file storing the operating / stopping of another processing device by the survival monitoring function, 109 ... Arrow for capturing the operating / stopping of another processing device by the time information transmission process 1.

Claims (2)

[Claims] 1. A distributed processing system comprising a transmission line and a plurality of processing devices connected to the common transmission line by a transmission control device, the function of transmitting time information on the transmission line at a constant cycle, and the transmission line. Characterizing time synchronization considering correction of transmission delay time by providing each processing device with a function to calibrate time management information in the processing device based on the time information to be acquired and the transmission time to the time information transmission processing device Time synchronization method for distributed processing system. 2. A distributed processing system according to claim 1, wherein the processing apparatus has a function of detecting whether another processing apparatus is operating / stopped, the level is set in the processing apparatus, and the own level is determined. A time synchronization method for a distributed processing system, characterized in that means is provided to enable time synchronization without having a specific time management processing device.