JPH1097505A - Information transmitting method and system therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a normal double system operation by transmitting a message to a connected processor when function codes are matched and transmitting the message from the processor to a transmission medium. SOLUTION: The processor 110 transmits the message generated by a program to a transmission controller (NCP) 11. The NCP 11 transmits the message on a loop transmission line 1. The transmitted message arrives at NCP 14 through NCP 12 and 13. Then, NCP 14 fetches the message, transmits the message which is fetched in the processor 140 and transfers the message on the loop transmission line 1 since the connected processor 140 requires the message. Then, the processor 140 transfers the message to the program requiring the message and the program executes a processing using the message.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system in which a plurality of information processing apparatuses transmit a message using a loop transmission line to which each apparatus is connected, and more particularly, to an information processing apparatus which performs a double system operation. The present invention relates to an information transmission method and an information transmission system suitable when a device is connected and a program in an information processing device requires clock management.

[0002]

2. Description of the Related Art A plurality of transmission control devices (NCPs) are connected to one conventional loop transmission line, and a processing device is connected to each transmission control device. Then, information such as necessary messages is transmitted between the processing devices.

Specifically, a plurality of programs are stored in each processing device, and a message is transmitted using a specific program among them. When sending a message, the contents of the message (sending processing device name,
The message is transmitted to the loop transmission path with a function code indicating the data content or the like added.

[0004] This is because, even when the destination of sending a message using the specific program is another program (receiving program) in the same processing device, the message is transmitted through the loop transmission path via the transmission control device. To send to. Then, each transmission control device performs a process of capturing a necessary message by referring to the content of the function code added to the message transmitted on the loop transmission path, and the captured message is sent to the processing device. Further, there is a method in which a message is transmitted in a loop on a transmission path, the transmitted message addressed to the own apparatus is taken into the receiving unit of the own apparatus, the message is passed to the processing apparatus, and then the corresponding message on the loop transmission path is discarded. I was

According to this method, each transmission control device can transmit a message without knowing the address of the receiving device, and all the messages are sent out on the transmission path, so that a pair of processings constituting a duplex system is performed. Even when a plurality of programs are stored in each of the devices and the programs are activated, the same order of message reception is guaranteed.

[0006] In addition, although the same order of reception is not guaranteed, a similar transmission method is disclosed in JP-A-56-40344.

As a method of allowing a program in the apparatus to input a current time and operating at a predetermined time or at a predetermined time, a method of managing a clock with a clock in each processing apparatus is generally implemented. Have been.

Further, as a method for preventing message redundancy, a method is provided in which a time stamp is added to a message so that one message is not processed when a message with the same time stamp is received. It is disclosed in JP-A-62-28510.

[0009]

In the above-mentioned prior art, a message transmitted by a program in a processing device is made to make a loop through a loop transmission path via a transmission control device, and a program which requires the message is stored. When the transmission control device connected to the device passes the message to the program in the capture processing device, the program operates, and when the current time is required, captures the current time from the clock in the processing device. The way was being taken.

For this purpose, an online processing device connected to a loop transmission path and storing a plurality of programs has
When a backup processing device (a device that stores the same program and forms a dual system so as to have the same configuration as the online processing device) is provided, when both the processing devices are operated asynchronously, Although the current time taken by the program must be the same, it is not always guaranteed that the current time is the same, and the processing related to the time differs between the online processing device and the backup processing device. The device may not have a normal backup function.

The above-mentioned prior art Japanese Patent Application Laid-Open No. Sho 62-28510 discloses a method of processing based on a time stamp added to a message. The time stamp is received from an external input / output device. It is only added to the message, and once set, the time stamp is not changed.

This is because, for example, in the processing of the same program stored in the online processing device and the backup processing device, when the current time is changed daily before or after 0:00, the online processing device is used. When the clocks of the backup processing devices are slightly different from each other, or even if they are correct, the time at which each program operates operates asynchronously. May perform the process on the day.

In particular, when the performance of the online processing device is different from the performance of the backup processing device, the operation of each processing device is different, and the possibility of capturing a different current time is further increased. Therefore, even if the online processing device actually breaks down and the backup processing device activates the backup function, the various processes that have been performed before the activation differ, and the normal backup function may not be provided. There is.

[0014] This is not only a process of capturing the current time, but also each program is executed after a lapse of a predetermined time.
The method of managing using the clock in each processing device when it is desired to receive activation at a predetermined time has the same problem as described above, and furthermore, the message sent to the program when the requested time is reached is It is conceivable that the messages generated in the processing devices and received from the loop transmission path become asynchronous, and the processing order of the time message and other messages may be different in each processing device.

Therefore, an object of the present invention is to allow each transmission control device to transmit a message without knowing the address of the receiving side, and furthermore, a plurality of programs are stored in each of a pair of processing devices constituting a duplex system. The programs in each processing device can store the same current time when the programs require the current time, or when the programs are activated at a predetermined time or at a predetermined time. An object of the present invention is to provide an information transmission unit that guarantees that the operation is performed in the reception order.

[0016]

An object of the present invention is to process a message transmitted via a common transmission medium and a common transmission medium based on a program stored in advance and send the message to the common transmission medium. A plurality of processing devices for generating a message including at least a function code indicating the content of data, information to be processed, and data indicating a type of the message, and connecting to each of the plurality of processing devices; The function code added to the message sent via the PC is compared with a function code stored in advance, and when the function codes match, the message is sent to the connected processing device and sent from the processing device. And a plurality of transmission control devices for transmitting the received message to the transmission medium.

Further, the above object is also achieved in that a plurality of processing devices connected to a common transmission medium fetch a message necessary for the own processing device from the common transmission medium based on the function code added to the message, and to store the function in the message. In the information transmission method of adding a code and transmitting the message to the common transmission medium, a message added with data representing at least a type of a message relating to time is transmitted to the common transmission medium, and a predetermined processing device receives the message. In addition, this can be achieved by transmitting the received message to the common transmission medium based on data indicating the type of the message added to the message.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be outlined below.

An information transmission method in which a message is transmitted using a loop transmission line in which at least one set of information processing devices performing a dual operation is connected is assumed.

Then, a message to which the current time is added is transmitted from a certain information processing apparatus (of course, one of the information processing apparatuses performing the dual system operation). Next, the program in each information processing device performing the dual operation operates by receiving the message, and when the current time is required, the current time added in the message is used. To perform predetermined processing.

A program in the information processing apparatus for performing the dual system operation is executed when a predetermined time elapses (or a predetermined time).
Sends a clock request message to receive activation. The message is transmitted from the information processing apparatus to the loop transmission path, and the clock management apparatus determined in advance by the clock registration message transmits a clock message to the loop transmission path at a predetermined time according to the request of the message. The transmitted message activates a program required by each of the information processing apparatuses performing the dual operation.

Thus, a backup processing device is provided for an on-line processing device for storing a program requiring time processing, and a clock such as a current time, a predetermined time elapsed, a predetermined time, etc. Operational identity in both processing units, including management, is guaranteed. Of course, even if the performances of the online processing device and the backup processing device are different, the same operation is guaranteed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a configuration diagram showing a configuration example of a system for carrying out the present invention. In the loop transmission line 1, transmission control devices 11, 12, 13, 14 (Network Communica
tionProcessor; hereinafter, referred to as NCP), and processing devices 110, 120, 130, and 140 are connected to the transmission control devices 11, 12, 13, and 14, respectively.

Also, each NCP has a clock (note that
Each processor connected to the NCP may have a clock).

Next, FIG. 3 shows an example of a data format of a message transmitted on the loop transmission line 1 constituting the present system.

In each field, "FC" is a function code, which is a code corresponding to the content of data. For example, it is 8-bit data indicating a number from “1” to “256”.

Each NCP refers to the function code and determines whether the data is necessary data. For this purpose, at least one type of predetermined data is stored in advance in each NCP, and if the data matches the function code, the data (message or the like) having the function code is determined as necessary data. I do.

Next, "SA" is the address (source address) of the NCP that has created and transmitted the message, and an address is predetermined for each NCP. "CC"
Is a serial number required for transmission, and is, for example, a value added to a message from the initial value 1 in the order of transmission on the loop transmission path 1. “Data” is information to be processed by the program.

The TM is the current time when a message is sent out, and is set by capturing from a clock of the NCP or a clock of a processing device connected to the NCP. The current time is, for example, data representing “year / month / day / hour / minute / second / millisecond”.

The CD is data representing the type of message, for example, "1; time registration", "2; clock management registration", "3; clock request", "4; clock response", "0; general message". , And necessary data is set in the OP as optional data. The data at the time of the general message is set to Data. At this time, "4; clock response" is set by each NCP, and the others are set by a program in the processing device.

"FCS" is error detection data, and "F" is a flag indicating the beginning and end of the message.

Each NCP has a field "F, FC, S
A, CD, OP, FCS "is used to control information transmission, and Data is not referred to. Each NCP compares the function code registered in the processing device in advance with the “FC field” of the message on the loop transmission line 1 from the connected processing device, so that the processing device It is determined whether or not it is necessary, and only when necessary, a message on the loop transmission path 1 is fetched.

When data is generated by executing a program, each processing device transmits the generated data content and a predetermined function code to the data processing device.
Field and FC field, and send it to the NCP connected to its own device.

The loop transmission path 1 includes data transmitted from each processing device via an NCP connected to the processing device,
Each processing device is a transmission medium for transmitting data received via an NCP connected to the processing device, and can be realized by, for example, an optical fiber cable, an electric cable, or the like.

Each processing device includes a storage unit having at least a storage area for storing a plurality of types of programs for performing predetermined processing, a storage area for storing the processing results of the programs, and a CPU for executing the programs. It is configured to have at least.

It should be noted that there is also a function of transmitting and receiving messages between programs stored in the processing device.

The processing device 110 and the processing device 140 constitute a so-called double system, and the processing device 110 functions as a main system and the processing device 140 functions as a sub system.
Therefore, the processing device 110 becomes an online processing device, and the processing device 140 becomes a backup processing device.

When the main system is in an abnormal state such as a failure, the processing executed by the main system is continuously executed by the slave system. In order to realize such a dual system configuration, it is assumed that the processing devices 110 and 140 have the same configuration and execute the same program at the same time. As described later, according to the present invention, the processing of the processing device 110 and the processing device 140
There is no need to perform synchronization, and asynchronous operation becomes possible.

Each NC connected to the loop transmission line 1
P has the same configuration. Each NCP has a function of taking in only necessary messages out of the messages transmitted on the loop transmission path 1 and sending them to the corresponding processing device. Here, each NCP determines whether or not a message is necessary by referring to a function code added to the message data described later, but is generally sent to a processing device connected to its own NCP. The received message is taken as necessary data and transmitted to the corresponding processing device.

The message sent from the processing device is
It is sent out onto the loop transmission path 1 via the corresponding NCP and transmitted on the loop transmission path 1. Where each NCP is
A destination address is not set in the message so that the message can be transmitted without knowing the system configuration or the value of the address of the processing device on the receiving side.

In the data transmitted on the loop transmission line 1, only necessary messages are transmitted to the corresponding processing device via the NCP.

The message receiving process using the system shown in FIG. 2 will be described later in detail with reference to a flowchart.

Each NCP formats the message received from the corresponding processing device so as to have the format shown in FIG. 3, and sends the message onto the loop transmission line 1 as a source.

When a message transmitted by itself as a transmission source returns after making a round of the loop transmission line 1, when the corresponding processing device determines that the message is needed, the message is transmitted. After sending the message to the corresponding processing device,
A so-called discarding process of deleting the corresponding message from the loop transmission line 1 is performed. If a message sent out on the loop transmission line 1 does not return within a predetermined time, a retry function for retransmitting the message a predetermined number of times may be used until the message returns. Such NCP information transmission control processing is performed exactly the same in each NCP.

Next, FIG. 1 is a flowchart showing one embodiment of the processing performed by each NCP.

When a message is received, first, it is determined whether the message is a message transmitted from the connected processing device or a message transmitted from the loop transmission path side, that is, the message is determined. The receiving direction is determined (step 901).

This determination is made to determine whether the message has been sent from the data bus connected to the corresponding processing device or the data bus connected to the loop transmission path. Can be determined by

If the message has been transmitted from the connected processing device, a message format is generated so as to have the format described in FIG. The message is sent out on the road and the process ends (step 917).

On the other hand, if the message is transmitted from the loop transmission path, the type of the message is referred to. The type is determined from the CD in FIG.

It is determined whether the message is a time registration message (step 902).
Is retrieved and set to the current time on its own clock (step 909).

Further, the NCP of the source of the message
Is determined with reference to the SA described in FIG. 3 as to whether it is the own NCP or another NCP (step 90).
7). If the source NCP of the message is the own NCP, the message is taken into the processing device, and then the message on the loop transmission path is discarded (step 908). If so, in order to transmit the message on the loop transmission path without performing any processing, the message is directly transferred to the loop transmission path and the processing is terminated (step 90).
9).

It is determined whether the transmitted message is a clock management registration message (step 903). If the message is a clock management registration message, the clock management device No. included in the OP of FIG. Is determined (step 910), and if they match, the self-processing device is recognized as a clock management device and registered in the clock management table in the NCP (step 911). Then, the process proceeds to step 907 described above. Also, the sent message is
It is determined whether the received message is a clock request message (step 904). If the received message is a clock request message, it is determined from the above-described clock management table whether the own device is a clock management device (step 91).
3) If the clock management device, the time management process is performed according to the request information (a request for a predetermined time lapse message or a request for a predetermined time message) included in the OP of FIG. 3 (step 914).

This clock management process is performed using a clock in the NCP or a clock (915) of a processing device connected to the NCP. Then, the process proceeds to step 907 described above.

When the clock reaches a predetermined time, the timer is started by an interrupt or the like, and the above-described step 91 is started.
Proceed to 6 to generate a format as a clock response and send a message to the loop. Further, when the transmitted message does not correspond to the above (clock response or general message), it is determined whether or not the message is required by the corresponding processing device with reference to the FC of FIG. 3 ( Step 905). If the message is required, the message is transferred to the corresponding processing device (step 906). Then, the process proceeds to step 907 described above. The above NCP processing shows that the conventional technology is provided with a function for adding the current time to a message to be transmitted and a time management function for transmitting a message at a predetermined time or at a predetermined time. ing.

Next, the message flow in the system shown in FIG. 2 will be described with reference to FIG.

The processing devices 110 and 140 store programs 310 and 311 and programs 340 and 341 respectively. When the program 310 is executed, a message 200 is generated.
11 and 341 receive and use.

In this case, first, the processing device 110 transmits the message 200 generated by the program 310 to the NCP
Send to 11 The NCP 11 is connected to the processing device 1
10 receives the message 200 from the loop transmission path 1
Send the message above. The message 200 transmitted on the loop transmission path 1 is transmitted through the NCPs 12 and 13 to the NC
Reach P14.

The NCP 14 is connected to the connected processing unit 140
However, since the message 200 is required, the message 200 is fetched, the fetched message is transmitted to the processing device 140, and the message 200 is transferred to the loop transmission path 1.

Then, the processing device 140 sends the message 2
00 to the program 341 requiring
And the program 341 executes a process using the message 200.

The message 200 transmitted on the loop transmission path 1 reaches the NCP 11. NCP11 is
Since the connected processing device 110 needs the message 200, it takes it in and sends it to the processing device 110, and the source NCP of the message 200 is its own NCP 11
Therefore, the message 200 is discarded. Then, the processing device 110 passes the message 200 to the required program 311, and the program 311 executes a process using the message 200.

Further, with reference to FIG. 5, a data flow in the case where a backup processing device is provided for the online processing device will be described. In this example,
It is assumed that the backup processing device 140 has a backup function with respect to the online processing device 110, the online processing device 110 becomes a main system, and the backup processing 140 becomes a subordinate system, and performs a dual system operation.

Therefore, the program configuration in the processing devices 110 and 140 is the same.
0 and the program 340 have the same contents.

FIG. 5A is a diagram showing a flow of the message 201 when the program 340 and the program 310 receive the message 201 transmitted on the loop transmission path 1 sent from, for example, a processing device (not shown). And the message 201 transmitted on the loop transmission path 1 is:
NCP14 and NCP11 respectively take in the NC
P14 and NCP11 are respectively the corresponding processing devices 1
The message 201 is transmitted to the processing devices 40 and 110, and the processing devices 140 and 110 respectively execute the program 34 in their own devices.
0, the message 201 is passed to the program 310, and the programs 340, 310 execute processing using the passed message 201, respectively.

Next, the program 340 and the program 310
When the process of (1) requires the current time, since the message is configured in the format of FIG. 3 by the process of NCP described in FIG. 1, the TM of FIG. 3 is extracted from the message and the process is executed. Often, the same processing of the program 340 and the program 310 is guaranteed.

For example, in taking in the present time, the program 340 and the program 310
And 110, the two clocks are not guaranteed to match, so programs 340 and 3
The identity of the operations of No. 10 cannot be guaranteed. In such a case, the function of the double operation is not normally exhibited.

The flow of a message at a predetermined time or a predetermined time will be described with reference to FIG.

This figure is also similar to FIG.
It is assumed that the backup processing device 140 has a backup function, the online processing device 110 is the main system, and the backup processing device 140 is the subordinate system, and performs a dual system operation.

FIG. 6A shows, for example, a message 2 transmitted on a loop transmission line 1 sent from a processing unit (not shown).
2 shows the flow of messages when the programs 340 and 310 receive the “02”.

The message 202 is received and the message 2
02, the programs that executed the processing using
Next, it is necessary to operate after a lapse of a predetermined time (for example, one minute later), and processing for sending clock request messages 203 and 204 is performed. Since the dual system operation is performed, the clock request messages 204 and 203 have the same contents, but the backup processing device 140
To prevent the same message from being sent out on the loop transmission path 1, the clock request message 204
14 is not sent. In order to prevent such transmission, when the main processing device is operating normally, the slave system may perform processing for preventing such transmission. Whether or not the main processing device is operating normally may be determined by checking at a predetermined time interval using a known technique.

Then, the processing device 110 sends a clock request message 204 to the NCP 11. NCP11 is
Clock request message transmitted from processing device 110
204 is taken out and transmitted to the loop transmission path 1. Then, the clock request message 204 is transmitted on the loop transmission path 1.

FIG. 6B shows a flow of transmitting a clock request message to the clock management device. The flow of a message specified to the clock management device will be described later. Here, the description will be made assuming that the NCP 13 is a clock management device.

The clock request message 20 shown in FIG.
4 loops through NCPs 12, 13, and 14,
Since P13 is a clock management device, the message 203 is taken into the NCP 13. Since the content of the clock request message is a request for the lapse of a predetermined time (one minute later), the NCP 13 registers the activation after one minute in the clock in the NCP 13 and temporarily processes the process.

FIG. 6C shows that a clock response message flows when a predetermined time has elapsed (one minute) and a predetermined time has been reached.

When the clock in the NCP 13 reaches a predetermined time, a clock response message 205 is transmitted from the NCP 13 to the loop transmission line 1 and makes a round via the NCPs 14, 11, and 12. Meanwhile, the clock response message 205 is NC
Processing devices 140, 1 taken in by P14, 11
10 sends a clock response message 205 to the processing device 1
40 and 110 pass the clock response message 205 to the programs 340 and 310, respectively.
Each 310 executes a process using the clock response message 205.

As described above, all the processing related to time is also processed as a message using the loop transmission path. Therefore, even if other messages occur at substantially the same time, the order of the messages related to other messages and time is guaranteed. Is done.
This is because the processing device 1 does not require any special synchronization means.
This indicates that the operations of the processing device 110 and the processing device 110 are not asynchronous.

It is assumed that the time lapse requests of the programs 340 and 310 are sent to the respective processing units 140 and 110 as in the prior art.
If a clock response message is issued using a clock inside the processor, the clock response message is generated in each of the processing devices 140 and 110, and the time may not match. Also, if the message 201 as shown in FIG. 5 occurs at substantially the same time even if the time is correct, the reception order of the clock response message 205 and the message 201 is determined by the program 340.
And 310 may be reversed. In this case, the function of the dual system operation is not normally exhibited as in the previous example.

FIG. 7 shows the flow of time registration and clock management registration messages.

FIG. 7A shows the flow of time registration.

To register the time of each of the NCPs 11, 12, 13, and 14 by manual setting from the processing device 120, the time registration message 206
It makes a round from 12 through NCPs 13, 14, and 11. Each of the NCPs 13, 14, 11, and 12 recognizes that the time registration message 206 is for time registration according to the flow of FIG. 1, and registers the time in its own clock.

FIG. 7B shows the flow of clock management registration.

When the NCP 13 is registered as a clock management device by manual setting or the like from the processing device 120, a clock management registration message 207 is sent from the processing device 120 to the NCP 12
From NCPs 13, 14, and 11. Each N
The CPs 13, 14, 11, and 12 recognize that the clock management registration message 207 is for clock management registration, and recognize that the NCP 13 in which the device No. in the message matches its own device is the clock management device. Register the clock management device.

As described above, according to the present invention, in a transmission system having a loop transmission path, a special N
Without providing a CP, all NCPs are provided with a backup processing device for the online processing device without recognizing the address of the NCP on the receiving side, and the program in the processing device requires time. Even if processing is required, the same current time can be captured, and the same order of messages received by both processing devices, including messages that have passed within the specified time and at the specified time, is maintained. You can do it.

Therefore, it is possible to guarantee that the online processing device and the backup processing device operate in a synchronized state without providing any special means for synchronization. Even if the performance of the online processing device and the performance of the backup processing device are different, the present invention is effective because the same reception order of messages is guaranteed in both processing devices.

[0085]

According to the present invention, the current time can be captured by the message received in each processing device, and the same reception order including time processing can be guaranteed. Even if a backup processing device is provided and operated, a normal double system operation can be guaranteed without providing a means for synchronizing the two devices.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a process according to the present invention.

FIG. 2 is a configuration diagram illustrating a configuration example of a loop system.

FIG. 3 is an explanatory diagram of a format of a transmitted message.

FIG. 4 is an explanatory diagram showing a flow of a message transmitted in a loop.

FIG. 5 is an explanatory diagram showing a flow of a message including a current time transmitted in a system including a backup processing device.

FIG. 6 is an explanatory diagram showing a flow of a time processing message in a system including a backup processing device.

FIG. 7 is an explanatory diagram showing a flow of time registration and clock management registration in a loop.

[Explanation of symbols]

1 Loop transmission path, 11, 12, 13, 14 Transmission control device (NCP), 110, 120, 130, 140 Processing device, 200, 201 Message, 203, 204
Clock request message, 205 ... Clock response message, 2
06: time registration message, 207: clock management registration message, 310, 311, 340, 341: program.

Claims (5)

[Claims] A function of processing a message transmitted via the common transmission medium based on a program stored in advance and indicating at least data contents for sending to the common transmission medium. A plurality of processing devices for generating a message including a code, information to be processed, and data representing the type of the message; and a message connected to each of the plurality of processing devices and transmitted through the common transmission medium. The function code added to the function code is compared with a function code stored in advance, and when the function codes match, the message is transmitted to the connected processing device, and the message transmitted from the processing device is transmitted. An information transmission system comprising: a plurality of transmission control devices for transmitting to a medium. 2. A method according to claim 1, wherein each of the plurality of processing devices has a clock, and data indicating that a message transmitted to the common transmission medium is a time registration message is data indicating a type of the message. A message is generated by adding a time, and when data representing the type of the message of the message received from the common transmission medium is a time registration message, the message is added to a clock provided in the processing device. 2. The information transmission system according to claim 1, wherein a registered time is registered. 3. The data processing system according to claim 1, wherein each of the plurality of processing devices sets data indicating a clock management device for managing time in the information transmission system as data indicating a type of the message, and also functions as the clock management device. A message is generated by adding a unique number of the processing device, and when the data indicating the type of the message of the message received from the common transmission medium is a clock management device message, the uniqueness of the processing device attached to the message is generated. 2. The information transmission system according to claim 1, wherein the number is compared with a pre-registered unique number, and the time management device is used based on a result of the comparison. 4. The data processing apparatus according to claim 1, wherein each of the plurality of processing devices sets data indicating that a message is received at a fixed time or a fixed time as data indicating a type of the message, and the fixed elapsed time or the fixed time. Message is generated by adding the time of the message, and the data indicating the type of the message of the message received from the common transmission medium is data indicating that the message is received at a certain time or at a certain time. 2. The information transmission according to claim 1, wherein when the processing device is a clock management device, the message is transmitted to the common transmission medium after a lapse of a predetermined time added to the received message or at a predetermined time. system. 5. A plurality of processing devices connected to a common transmission medium fetch a message necessary for the own processing device from the common transmission medium based on a function code added to the message, and add a function code to the message. In the information transmission method of adding and transmitting the message to the common transmission medium, a message to which at least data indicating a type of a message relating to time is added is transmitted to the common transmission medium, and a predetermined processing device receives the message, An information transmission method, comprising: transmitting the received message to the common transmission medium based on data representing the type of the message added to the message.