JPH1141375A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system which can suitably and more efficiently perform communication between a host computer and plural center side network control units (C-NCU). SOLUTION: The cascade connection of 1st, 2nd and 3rd C-NCU 4, 5 and 6 to a host computer 3 is performed. A telegraphic message is transmitted from the 2nd C-NCU 5 to the 1st C-NCU 4. The 1st C-NCU 4 transmits a telegraphic message containing the same data to the host computer 3. When the telegraphic message is normally transmitted, the host computer 3 returns ACK to the 1st C-NCU 4. The 1st C-NCU 4 converts the ACK into telegraphic message and transmits it to the 2nd C-NCU 5. From this telegraphic message, the 2nd C-NCU 5 recognizes that the telegraphic message transmitted to the host computer 3 is delivered without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication system applied to a telemeter system for transmitting meter reading information from a gas meter or the like to a center system via a telephone line.

[0002]

2. Description of the Related Art Conventionally, a telemeter system for transmitting meter reading by a gas meter or the like to a host computer provided in a center system has been widely used. This system includes a center system including a center network controller (hereinafter, referred to as “C-NCU”) connected to a host computer, and a terminal system including a terminal device connected to a terminal device such as a meter. The system is connected via a telephone line. Communication between the host computer and the gas meter is performed bidirectionally, and meter reading data and emergency data such as gas leaks are periodically or irregularly transmitted by a command from the host computer or by a call from the gas meter. Transmit.

The applicant of the present application has proposed an example of such a telemeter system in Japanese Patent Application No. 7-305553. According to this specification, a plurality of C-NCUs provided in the center system are connected in a daisy chain, so that the number of gas meters and the like can be increased.

[0004]

However, when a plurality of C-NCUs are daisy-chain-connected to a host computer, the host computer, the C-NCUs, and each C-NCU are connected.
It has been found that data communication between NCUs may not be performed properly and smoothly. Specifically, it has the following problems.

(1) When the C-NCU sends data to the host computer for some reason, if the data does not reach the host computer, the host computer may not return a response message to the C-NCU. is there. Therefore, the C-NCU may not be able to confirm whether data has actually arrived at the host computer. Further, the C-NCU erases the data when the data is transmitted, so that if the data does not reach the host computer, the C-NCU cannot take measures such as retransmission.

(2) When the C-NCU sends data to the host computer, the data is congested and each C-NCU
When a transmission delay occurs between the host computer and the C-NCU, response data may be returned to the C-NCU very late. Therefore, C-NC
If timeout processing is performed in U, there is a case where it is not possible to distinguish between a response message of data newly transmitted to the host computer and a response message of previously transmitted data.

(3) When the host computer and the C-NCU are off-line, each C-NCU is
Since the C-NCU is in the off-line state, data cannot be exchanged between the C-NCUs.

(4) When the host computer and the C-NCU are off-line, each C-NCU separately stores data received from the terminal-side system. Then, when the host computer and the C-NCU are restored to the online state, each C-NCU transmits the stored data to the host computer, and the host computer transmits the terminal call from each C-NCU in time order from each C-NCU. Will be received. for that reason,
When the host computer performs the processing based on the time order using the received data, it is necessary to read all the data and then rearrange the data in the time order and perform the processing.

(5) The C-NCU transmits the stored data to the host computer first even when receiving the emergency data such as gas leak from the terminal side system while transmitting the stored data to the host computer. I do. Therefore, the host computer cannot take immediate action for the emergency data.

(6) The host computer is provided with a plurality of C-
When an attempt is made to directly communicate with a lower-level C-NCU among the NCUs, the telegram always passes through the C-NCU interposed therebetween, so that the telegram includes the communication result of the interposed C-NCU. Therefore, for example, when a transmission error occurs, it is difficult to check which C-NCU has an error.

(7) Host computer and lower CN
When the CU communicates directly, the C-
The NCU enters a pass mode in which data to be received is passed. However, conventionally, when canceling the passing mode, all C-NCUs are reset. Therefore, for example, if data is held in the C-NCU, the data will be lost.

(8) The host computer operates each C-NC
If you want to get responses to common instructions from U,
It is necessary to create and transmit messages in accordance with the number of connected C-NCUs. In addition, since replies from each C-NCU are also returned separately, it takes time to process.

The present invention has been made in view of these problems, and has as its object to provide a communication system capable of appropriately and more efficiently performing communication between a host computer and each C-NCU.

[0014]

The object of the present invention is to provide a center system having a plurality of network controllers connected to a host computer, and a terminal network connected to the network controllers via a communication line. In a communication system including a terminal system having a control device, a plurality of network control devices are cascaded, and each network control device transmits data to a host computer or another network control device. The host computer or another network controller receives the transmission result data indicating the data transmission result from the computer or another network controller, and receives the data from each network controller. The transmission result data is transmitted. Then, the identification information of the transmission source is added to each data, and each network control device determines whether or not the communication result of the data transmitted by itself is returned based on the identification information.

According to this configuration, the network control device that has transmitted data to the upper or lower order always returns a data transmission result from the upper or lower order with identification information added thereto. It is possible to reliably recognize whether the data has successfully arrived at the destination. Also, if the transmitted data is deleted when the reply of the transmission result arrives,
As in the conventional case, the data is not lost, and the data is not re-transmitted due to the slow response from the host, so that the data is not duplicated.

Another object of the present invention is to provide a communication system having the same configuration as described above, wherein the host computer and the highest-level network control device are not connected to each other in a line-like manner. The control device notifies the lower-level network controller of this fact, and each lower-level network controller
Even when the notification is received, communication between the network control devices is continued.

When the network control device is not connected to the network, the network control device accumulates data held by itself or transmitted from each network control device to the host computer, and communicates with the host computer at the highest level. When the network controller is connected to the other network controller, the network controller transmits data to the host computer in the order of accumulation. In addition, data accumulation is continuously performed from the highest-level network controller to the lower-level network controllers.

According to these configurations, even when the host computer and the highest-level network control device are not connected via a line, the respective network control devices can communicate with each other. In this case, data to be sent from each network control device to the host computer is stored in the network control device in chronological order, and when connected via a line, data is transmitted to the host computer in the stored order. Therefore, the host computer does not need to rearrange the data in chronological order as in the related art, and the processing becomes easy.

Another means for solving the problems according to the present invention is:
In the communication system having the same configuration as above, each network control device, when data having a high degree of urgency such as gas leak data is transmitted from the terminal side system, transmits the data to the host computer with priority. . According to this configuration, the host computer can immediately respond to data with high urgency.

Another means for solving the problems according to the present invention is:
In the communication system having the same configuration as described above, when each network control device receives a predetermined signal from the host computer or another network control device, the network control device enters a pass mode in which data received thereafter is passed. . Further, the host computer or another network control device transmits data for canceling the passage mode to the network control device in the pass mode via the upper or lower network control device.

According to the above configuration, the host computer can place the network control device in the passing mode, so that the host computer can thin out the network control device and directly communicate with the lower-level network control device. Further, when canceling the passing mode, by sending data to that effect via the upper or lower network controller, the network controller can be surely released without resetting and releasing the network controller as in the related art.

Another means for solving the problems according to the present invention is as follows.
In the communication system having the same configuration as described above, the host computer transmits a command message including a command to sequentially transmit data to the lowermost network controller to the uppermost network controller, and transmits the uppermost and lowermost messages. Each of the network controllers excluding, when receiving the command message, captures the data in the message, transmits the command message to the lower network controller, and receives the reply message of the command message from the lower network controller. Adds its own data and sends it to the upper-level network controller.The lowest-level network controller fetches the data in the message when it receives the command message, and adds its own data to the upper-level network controller. The transmitted reply message is transmitted.

According to this configuration, the host computer can receive reply messages from all network control devices by transmitting only one command message to the highest-level network control device. It is not necessary to transmit a command message to each of the network control devices. In addition, since the response data of all network control devices is added to one response message, processing of the response message by the host computer becomes easy.

[0024]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

<First Embodiment> FIG. 2 is a block diagram showing a configuration of a telemeter system according to a first embodiment of the present invention. According to the figure, this telemeter system is
A center system 1 and a terminal system 2 are connected via a telephone network L.

The center-side system 1 includes a host computer (hereinafter, simply referred to as “host”) 3 and a first center-side network controller (hereinafter, referred to as “C-NCU”) 4.
And a second C-NCU 5 and a third C-NCU 6. The first C-NCU 4 is connected to the host 3, and the C-NCUs 4, 5, and 6 are cascade-connected as shown in FIG. Each of the C-NCUs 4, 5, and 6 is a host 3
Or upper I / F 7 for connecting to upper C-NCU
And lower I / F 8 for connecting to lower C-NCU
Respectively. This upper I / F 7 and lower I
/ F8 is connected by the communication cable 9 so that each C-
The NCUs 4, 5, and 6 are connected and communicate with each other.
Note that the number of C-NCUs is not limited to the above three, and can be increased according to the scale of the terminal system 2.

On the other hand, the terminal system 2 comprises a plurality of terminal devices 10 and a telegram-type meter 1 connected to each terminal device 10.
1 and a telephone 12. Further, the telephone line network L includes a center-side switching center 1 on each of the systems 1 and 2 sides.
3 and the terminal-side exchange 14 are interposed.

FIG. 4 is a block diagram showing the internal configuration of the first C-NCU 4 shown in FIG. The configurations of the second and third C-NCUs 5 and 6 are basically the same. According to the figure, the first C-NCU 4 is the upper I / F 7 described above.
And a lower I / F 8 and a controller 15 for performing various controls
And a modem 16 for communicating with the terminal side system 2.
And a line I / F 18 connected to the telephone line 17.

The control unit 15 is a CPU 1 serving as a control center.
9, a RAM 20 for storing variable data and the like, a ROM 21 for storing predetermined programs and constant data, and a flash memory 22.

The upper I / F 7 and the lower I / F 8 are both connected to the host 3 or another C-NCU via the communication cable 9 by the connector terminal 23 of the RS232C specification. The line I / F 18 is connected to the terminal-side system 2 via the telephone line 17 by terminals 24 such as modular jacks. In FIG. 4, the first
Although the number of lines of the C-NCU 4 is two, the number of lines can be increased or decreased. In this embodiment, the first C-NCU 4 has two lines (line number 1, line number 1).
2), the second C-NCU 5 has one line (line number 1),
It is assumed that two telephone lines 17 (line numbers 1 and 2) are connected to the third C-NCU 6, respectively.

Each of the C-NCUs 4 according to the first embodiment
When transmitting data to the host 3 or another C-NCU, each of the hosts 5 and 6 has a function of receiving transmission result data indicating a data transmission result from the host 3 or another C-NCU. 3 or other C-NCUs, each C-N
When data is received from CUs 4, 5, and 6, each C
-Has a function of transmitting transmission result data to the NCUs 4, 5, and 6.

That is, when each of the C-NCUs 4, 5, and 6 receives the meter reading data from the telegram-type meter 11 of the terminal side system 2 by calling the terminal or the like, the other C-NCUs or the host 3 in a predetermined telegram format. Send data to.
At this time, the other C-NCU or the host 3 returns a data transmission result to each of the C-NCUs 4, 5, and 6 that transmitted the data. Thereby, the C-N that transmitted the data
The CUs 4, 5, and 6 can recognize whether or not the data has successfully arrived at the destination.

The details will be described below. First, as shown in FIG. 5, the message format transmitted and received between the host 3 and each of the C-NCUs 4, 5, and 6 is "STX (Start of Text)" indicating the start of text, and "c" indicating the line number.
h, "No" indicating the number of the message, "Data", "ETX (End of Text)" indicating the end of the text, and "BCC (Block Checker)" for checking the transmission error of the message.
k Character) ”.

The channel numbers of the respective C-NCUs 4, 5, and 6 are added to “ch”. In this embodiment, ch01 and 02 correspond to the first and second lines of the first C-NCU 4, and ch03 is the first. 2 corresponding to the line 1 of the C-NCU 5,
Correspond to the lines 1 and 2 of the third C-NCU 6, respectively. Further, ch00 corresponds to the first C-NCU4, and c00
h10 corresponds to the second C-NCU 5, and ch20 corresponds to the third C-NCU 5.
Corresponds to C-NCU 6 of FIG. "No" means C-NCU
4, 5, and 6 are message numbers generated arbitrarily. Each CN
The CUs 4, 5, and 6 can identify from which C-NCU the message was transmitted by confirming the above “ch” and “No”.

FIG. 1 is a sequence diagram showing a communication procedure performed between the host 3 and each of the C-NCUs 4, 5, and 6 according to the first embodiment. Now, it is assumed that the terminal call data from the terminal side system 2 is received by the line number 1 of the second C-NCU 5. At this time, a message is sent from the second C-NCU 5 to the first C-NCU 4 in the message format shown in FIG. Specifically, “STX + 03 + 11
+ Data + ETX "is transmitted.
Here, since the “ch” of the message is 03, it is understood that this message is a message based on the data received by the line number 1 of the second C-NCU 5. “No” is 1
1, which is a unique number arbitrarily generated by the second C-NCU 5. The data in this message is transmitted to the first C-NCU 4 and stored in the RAM 20 until a reply message is returned.

Next, the first CN receiving this message
The CU 4 sends the same message to the host 3. At this time, “No” is omitted and sent. Host 3
Returns the acknowledge message “ACK (Acknowledge)” to the first C-NCU 4 if it can receive this message.

First C-NCU 4 that has received “ACK”
Indicates that the transmitted message is a lower-level C-NCU (in this case,
Since this is sent from C-NCU5),
"ACK" is converted to a message format and the second C-NC
Reply to U5. At this time, the first C-NCU 4 adds “No” omitted when transmitted to the host 3,
"+" Indicating that "ACK" was returned in "Data"
(See FIG. 6).

The second C-NCU 5, which has received this message from the first C-NCU 4, checks "ch" in the message and determines whether or not the message has been sent to itself. If the message is sent to itself, the data in the message is captured. In this case, since “+” is inserted in the data, the second C-NCU 5 can confirm that the transmitted data has reached the host 3 safely. And the second C
-The NCU 5 deletes the data stored in the RAM 20 until the response message is received.

On the other hand, if data is garbled during transmission from the second C-NCU 5 to the host 3 and the contents of the data received by the host 3 cannot be recognized, the host 3
For the first C-NCU 4, "NAK (Negative Ackno
wledge) ”.

First C-NCU 4 receiving “NAK”
Indicates to the second C-NCU 5 that the data of the message is “-”.
(See FIG. 7). Thereby, the second C-
The NCU 5 can confirm that the transmitted data has not reached the host 3.

The first C-NCU 4 measures the time since the first C-NCU 4 transmitted a message to the host 3, and when there is no response from the host 3 for some reason or when the host 3 is off-line, etc. If a timeout is detected, the message data is sent to the second C-NCU 5 in the same manner as described above.
Insert '-' and send. Then, the second C-NCU 5 that has received the data with the “-” inserted performs processing such as retransmission.

Also, when a message is generated from the third C-NCU 6 to the host 3, as shown in the lower part of FIG. 1, the message is transmitted via the first C-NCU 4 and the second C-NCU 5. The transmission result is returned.

As described above, the transmission result of the transmitted message is always returned to the second C-NCU 5 that has transmitted the data toward the higher order with its own line number added. The C-NCU 5 can surely recognize whether the transmitted data has reached the host 3 safely. Therefore, data is not lost as in the related art. In the past, data was retransmitted because the response from the host was slow, which caused data duplication.However, if data is retransmitted after the transmission result is replied, data duplication may occur. Disappears. Therefore, the message can be transmitted efficiently.

FIG. 1 shows a case where data is transmitted from a lower-level C-NCU to a higher-level C-NCU or the host 3.
When transmitting data to U, the transmission result may be returned from lower to higher.

<Second Embodiment> Next, a second embodiment of the present invention will be described. When the host 3 becomes offline with the highest-level C-NCU (in this case, the first C-NCU 4) due to maintenance, failure, power failure, or the like,
Conventionally, the C-NCU 4 is also offline.

When the host 3 and the first C-NCU 4 change from the offline state to the online state, for example, for each of the C-NCUs 4, 5, and 6, the terminal-side system 2
When the data received from the terminal-side system 2 is transmitted, the order of the data received from the terminal-side system 2 to the C-NCUs 4, 5, and 6 is disturbed, and the host 3 needs to rearrange and process the data in time order. Is very stressful.

Therefore, in the second embodiment, the host 3
And when the first C-NCU 4 is offline,
Communication between the C-NCUs 4, 5, and 6 can be continued, and the C-NCUs 4, 5, and 6 collect data received from the terminal-side system 2 in any C-NCU in the order received. To accumulate. Then, when the state changes from the offline state to the online state, the stored data (hereinafter, referred to as “stored data”) is transmitted to the host 3 in the order of storage. If you do this,
In the host 3, each C-NCU 4,
Since the data can be received in the order in which the data arrives at 5, 6, there is no need to rearrange the data in the host 3, and the data can be processed efficiently. Therefore, the processing load on the host 3 can be significantly reduced.

More specifically, the first C-NCU
4 is a function of notifying the host 3 and the first C-NCU 4 to other C-NCUs when the host 3 and the first C-NCU 4 are in an offline state, and a host that the host 3 owns or sends from the other C-NCU. 3 and a function of transmitting data to the host 3 in the order of accumulation when the host 3 and the first C-NCU 4 are connected in a line. . Other configurations are the same as in the first embodiment.

FIG. 8 is a sequence diagram showing a communication procedure between the host and the C-NCU according to the second embodiment. When the host 3 goes offline, the ER signal is turned off. The ER signal is a signal equivalent to a DTR (Data Terminal Ready) which is a control signal of the RS232CI / F. The first C-NCU 4 recognizes that the host 3 is offline by turning off the ER signal.

Then, the first C-NCU 4 is
-A message "ESC (1bh) + 'd'" indicating to the NCU 5 that the connection with the host 3 has gone offline.
Send The second C-NCU 5 is the first C-NCU.
When "ESC + 'd'" is received from No. 4, it is transferred to the third C-NCU 6 as it is. Thus, the second and third C-NCUs 5 and 6 communicate with the host 3 and the first C-NCU.
4 is off-line. And
Data transmission / reception is performed between the C-NCUs 4, 5, and 6 while maintaining the same state. Therefore, as before,
When the host 3 and the first C-NCU 4 are offline, the C-NCUs 4, 5, and 6 do not go offline, and the mutual data between the C-NCUs 4, 5, and 6 do not change. Transmission and reception are possible.

Next, the second C-NCU 5 transmits the data received from the terminal side system 2 to the first C-NCU 4. In this case, in order to determine that the data should be stored in the first C-NCU 4, the first digit "!" Add the 'symbol. Since the last digit of “ch” remains unchanged, it can be determined from which C-NCU the data was transmitted.

Upon receiving this message, the first C-NCU 4 looks at the "ch" portion of the message, determines that it is data to be stored, and stores the data contained in the message in the RAM.
20. Then, to the second C-NCU 5, the message "STX + 03 + 13 + '!' +
ETX ". At this time, '
'!' And send.

The second C-NCU 5 has the same “ch” and “No” as the transmitted message and has a “!” ', The data transmitted by itself is safely transmitted to the first C-NC.
Recognizing that the data is stored in U4, the same data as the transmitted data stored in the RAM 20 is deleted. Also,
If the transmitted message has not arrived, resend the data.

When there is data received from the terminal side system 2 in the third C-NCU 6, the first digit "!"'And send. Second C-NCU
5 transmits the message received from the third C-NCU 6 to the first C-NCU 4 as it is when the data accumulation processing is not performed by itself.

As described above, in the off-line state, the C-NCU that has received the data from the terminal-side system 2 transmits a message so as to be stored in the higher-level C-NCU. The transmitted data is stored in the higher-order C-NCU in chronological order.

Next, it is assumed that data is accumulated in the first C-NCU 4, and the data accumulation area of the RAM 20 in the first C-NCU 4 reaches a maximum (a predetermined capacity may be used). In this case, the buffer full data “ESC + 'f'” is transmitted to the second C-NCU 5. The second C-NCU 5 transmits the “ESC” from the first C-NCU 4.
+ 'F', the data received from the terminal side system 2 is not transmitted to the first C-NCU 4 and the own RA
The data is stored in the data storage area in M20.

On the other hand, the first C-NCU 4 whose data storage area has reached the maximum thereafter transmits data to the second C-NCU 5 when receiving data from the terminal side system 2. At this time, the second C-NCU 5 communicates with the first C-NC
When the data to be stored is transmitted from U4, the data is stored in the storage area in the RAM 20, similarly to the data to be stored transmitted from the third C-NCU 6 lower than itself.

Next, a case where the state between the host 3 and the first C-NCU 4 is restored from the offline state to the online state will be described with reference to FIG. The first C-NCU 4 is
When it is confirmed that the ER of the host 3 has been turned on by turning on the ER of the host 3, the second C-NCU 5
The message "ESC + 'indicating that it has gone online
c '". The second C-NCU 5 that has received “ESC + 'c'” further transmits the same message to the third C-NCU 6
Transfer to By this message, the second and third C-NCUs
5 and 6 recognize that they are online.

Then, the first C-NCU 4 transmits the stored data to the host 3 in the order of storage. The first C-
The NCU 4 sends a RAM every time data is sent to the host 3.
20 and deletes the transmitted data. By doing so, if an area that can be stored in the RAM 20 can be secured, the RAM 2 is stored in the second C-NCU 5.
0 indicating that there is an area that can be stored in the "ESC
+ 'E'. The second C-NCU 5 is the first C-NCU 5
-When "ESC + 'e'" is received from the NCU 4, the data stored in the RAM 20 up to that point is stored in the first C
-Send to NCU4. The first C-NCU 4 accumulates the data sent from the second C-NCU 5,
The previously stored data is sent to the host 3.

Here, for example, when the first C-NCU 4 sends the stored data to the host 3, R
When the data in the AM 20 reaches the maximum, even if data is received from the terminal side system 2 during the transfer of the stored data, the data is not stored in the RAM 20 of the terminal itself, and the second data is stored.
Once to the C-NCU 5. Then, when the transfer is started, the data is stored in the second C-NCU 5 that has not reached the maximum, and thereafter, the data is stored in the second C-NCU 5 from the first C-NCU 5.
-Transmit the stored data to the NCU 4. By doing so, the time series of data can be surely kept.

As described above, if the data received from the terminal side system 2 is stored in the memory in the first C-NCU 4 in a time-series manner, the data is stored in the host 3 in the order in which the data was stored in the online state. Can be sent. Therefore, the host 3 can process the data in the order in which the calls are originated by the terminal-side system 2, and the processing load on the host 3 can be reduced.

In the above description, data accumulation is
Although the storage is performed in order from the first C-NCU 4, the storage order is not limited to this, and the storage may be performed from the second C-NCU 5 or the third C-NCU 6.

<Third Embodiment> Next, a third embodiment of the present invention will be described. For example, when the first C-NCU 4 is transmitting the above-described stored data to the host 3,
Even if the emergency data is sent from the terminal side system 2, if the emergency data is transmitted after the transmission of the stored data is completed, the host 3 delays the emergency response.

Therefore, in the third embodiment, in such a case, as shown in FIG. 10, when the emergency data is received, the transmission of the stored data to the host 3 is temporarily stopped.
The urgent data is transmitted to the host 3 first. In this way, for example, even in a situation where there is a person in the terminal side system 2 and a response from the host 3 is necessary, the host 3 can quickly take an action on the emergency data.

More specifically, each C-NCU 4, 5,
Reference numeral 6 has a function of, when data having a high degree of urgency is sent from the terminal-side system 2, sending the data to the host 3 with priority. Other configurations are the same as in the first embodiment. Then, as shown in FIG. 11, the second C-NCU 5 receives emergency data from the terminal-side system while the first C-NCU 4 is transmitting stored data to the host 3 after entering the online state. And 2nd C
-The NCU 5 sends its emergency data to the first C-NCU 4. At this time, the first C-NCU 4 stops transmitting the stored data to the host 3, and transmits the emergency data to the host 3 with priority.

Next, a command is returned from the host 3 to the first C-NCU 4 as an answer, and the first C-NCU 4 recognizes that the emergency data has safely arrived at the host 3 and also stores the stored data. Resume transmission. Note that the above command is also transmitted to the second C-NCU 5.

The first C-NCU 4 is a lower C-NCU.
If the data received at 5 and 6 is normal data, the received data is stored and the stored data stored before is given priority and transmitted to the host 3.

It should be noted that the emergency data is transmitted to the host 3 not only during the time when the first C-NCU 4 is transmitting the stored data, but also when the host 3 and each C-NCU 4, 5, 6 perform normal operations. It also applies when exchanging data.

<Fourth Embodiment> FIG. 12 is a sequence diagram showing a communication procedure between a host 3 and C-NCUs 4, 5, and 6 according to a fourth embodiment. The feature of the fourth embodiment is that, when communication is performed from the host 3 to specific C-NCUs, the mode is a pass mode in which the data received by the C-NCU interposed therebetween passes.

That is, when each of the C-NCUs 4, 5, and 6 receives a predetermined signal from the host 3 or another C-NCU, the C-NCU has a function of entering a pass mode for passing data to be received thereafter. Host 3 or another C-NCU
For the C-NCU in the passage mode, the C-NCU concerned
Has a function of transmitting data for canceling the passing mode via a lower C-NCU. Other configurations are the same as in the first embodiment.

For example, when the host 3 wants to directly communicate with the second C-NCU 5, the host 3 sends the first C-NCU 4 to the first C-NCU 4 interposed therebetween.
A message is sent that allows all data received by U4 to pass therethrough without processing.

In this manner, the host 3 sends the second C
The message sent to the NCU 5 and the message sent from the second C-NCU 5 to the host 3 pass through the first C-NCU 4. Therefore, the host 3 and the second C-NCU 5 can directly communicate with each other.

More specifically, as shown in FIG. 12, the host 3 transmits a message “STX + 00 + thru + ETX” to the first C-NCU 4 to inform the first C-NCU 4 to pass through. As a result, the first C-NCU 4 transfers the received data as it is from upper to lower or from lower to upper. For example, the host 3 sends the message “STX +
ch + No + data + ETX ”to the first C-NCU 4
, The message is passed by the first C-NCU 4 and received by the second C-NCU 5. Also, the second C-NCU 5 to the first C-NCU 4
Sent to "STX + ch + data + ET"
X ”also passes through the first C-NCU 4 and directly
Reaches

Further, when the host 3 and the third C-NCU 6 perform direct communication, the host 3
The message "STX + 10 + thru" to be passed to CU5
+ ETX ”may be transmitted.

As described above, when the host 3 has a specific C-NCU
If it is desired to directly communicate with the C-NCU, the intervening C-NCU may be set to the pass mode. By doing so, unlike the conventional case, even when direct communication is desired, the message is not processed by the C-NCU on the way, and the host 3 can quickly exchange the message with a specific C-NCU. Therefore, the communication time can be reduced. In addition, messages that are directly exchanged include C
Since the communication result of the NCU is not included, it is possible to easily check, for example, when a transmission error occurs.

It should be noted that the message to be set to the pass mode may be sent not only from the host 3 but also from each of the C-NCUs 4, 5, and 6.

Next, a procedure for canceling the passing mode will be described. When the C-NCU in the passing mode is returned to the normal mode by the message from the host 3, since the C-NCU in the passing mode cannot receive the message, the C-NCU from the upper or lower C-NCU receives the message. A specific message to cancel the passing mode is transmitted.

Specifically, as shown in FIG.
When the second C-NCUs 4 and 5 are in the pass mode, the host 3
Transmits a message “STX + 20 + No + Nthr + ETX” for canceling the passage mode to the third C-NCU 6.

The third C-NCU 6 transmits a message “0xc (FF)” for canceling the passing mode to the second C-NCU 5 in response to the instruction message. The second C-NCU 5 that has entered the passing mode is a lower third C-NCU 6
Only the message “0xc (FF)” is monitored from among the messages sent from, and when this message is received, the mode returns to the normal mode. Then, a message “STX + 10 + THRT + ETX” indicating to the host 3 that it has returned to the normal mode.
Send Next, returning the first NCU 4 from the passing mode to the normal mode is also performed by transmitting “0xc (FF)” from the second C-NCU 5.

As described above, when the passing mode is released, the passing mode can be easily released by transmitting data to that effect via the C-NCU lower than the C-NCU which is the passing mode. As described above, it is possible to reliably control the return from the passing mode to the normal mode without resetting all the C-NCUs.

Note that the message "0x
“c (FF)” may be transmitted from a higher-level C-NCU. Also, the C-NCU in the passing mode
However, when emergency data is received from the terminal-side system 2, the passing mode may be immediately released.

<Fifth Embodiment> FIG. 14 shows a fifth embodiment of the present invention.
FIG. 7 is a sequence diagram illustrating a communication procedure between a host 3 and C-NCUs 4, 5, and 6 according to the embodiment. The feature of the fifth embodiment is that the host 3 transmits common data to all the C-NCUs 4, 5, and 6 to
When it is desired to obtain a response to the data from the host 3, one command message transmitted from the host 3 is sequentially transmitted to each C-NCU 4,
Each of the C-NCUs 4, 5, and 6 receives response data corresponding to the data in the command message to one response message, and is received by the host 3 via the command messages.

In this way, the host 3 can receive reply messages from all the C-NCUs 4, 5, and 6 by transmitting only one command message to the first C-NCU 4. It is not necessary to transmit a command message to each of the C-NCUs 4, 5, and 6 as in the related art. In addition, since the reply data of all the C-NCUs 4, 5, and 6 are added to one reply message, the processing in the host 3 becomes easy.

Specifically, the host 3 performs the first C-NC
U4 has a function of transmitting a command message including a command to sequentially transmit data to lower-order C-NCUs 5 and 6, and the second C-NCU 5 transmits data in the message when the command message is received. The function of taking in and transmitting a command message to the third C-NCU 6, and adding the own data when a response message of the command message is received from the third C-NCU 6 to the first C-NCU 6.
The third C-NCU 4.
The CU 6 has a function of taking in data in the message when receiving the command message, and transmitting a response message including its own data to the second C-NCU 5. Other configurations are the same as in the first embodiment.

Then, as shown in FIG.
Transmits the command message in which “ch” is ff to the first C-NCU
Send to 4. The first C-NC that has received this command message
U4 determines that "ch" of the message is ff, and fetches the data included in the command message. Then, while performing processing according to the data, the second C-NCU 5
, And waits for a reply message from the second C-NCU 5.

Similarly, the second C-NCU 5 fetches the data contained in the command message and outputs the third C-NCU 5.
The same instruction message is transmitted to the CU 6. When receiving the command message, the third C-NCU 6, which is the lowest order, performs a process according to the data included in the command message, creates a reply message as a response to the command message, and creates a second C-NCU.
Send to NCU5. At this time, reply data ("30" in FIG. 14) for the process corresponding to the data contained in the command message is transmitted to the reply message.

The second C-NCU 5 receiving the reply message
Adds its own response data (“3c” in FIG. 14) to the command message sent from the host 3 and
Send to NCU4. And the first C-NCU 4 is:
Similarly, the response message (“3f” in FIG. 14) is added, and the response message is transmitted to the host 3. At this time, “No” in the message is omitted and sent.

As described above, the host 3 can acquire a reply to the data included in the command message from each of the C-NCUs 4, 5, and 6 only by transmitting one command message to the first C-NCU 4. it can. Therefore, unlike the related art, it is not necessary to individually create and transmit a message to each of the C-NCUs 4, 5, and 6, respectively.

The reply messages from each of the C-NCUs 4, 5, and 6 are not sent separately as in the prior art, but
It is sent as one message including the response data of each C-NCU 4, 5, and 6. Therefore, the host 3 can quickly process the reply message. Therefore, the processing in the host 3 can be reduced, and the total transmission processing time can be shortened.

The present invention is not limited to the above embodiment, and many modifications and changes can be made to the above embodiment within the scope of the present invention.

[0091]

As described above, according to the present invention, the network control device that has transmitted data to the upper or lower order always returns the data transmission result from the upper or lower order in the form of adding the identification information. Therefore, it is possible to surely recognize whether or not the data transmitted by itself has reached the transmission destination. Also, if the transmitted data is deleted when the response of the transmission result arrives, the data is lost as in the conventional case, or the data is duplicated by retransmission because the response from the higher rank is slow. Disappears. Therefore, it is possible to provide a communication system capable of appropriately and efficiently transmitting.

Even when the host computer and the highest-level network controller are not connected to each other via a line, the respective network controllers can communicate with each other. The data sent from the device to the host computer is stored in the network controller in chronological order, and when connected via a line, the data is transmitted to the host computer in the stored order. There is no need to rearrange the data, and the processing can be reduced.

Further, when high urgency data such as gas leak data is sent from the terminal side system, each network control device sends the data to the host computer by giving priority to the data. Can respond to high data immediately.

Further, since the network control device has the pass mode, the host computer can thin out the network control device and directly communicate with the lower-level network control device. For this reason, the communication time can be reduced, and the directly exchanged message does not include the communication result of the intervening network control device. Therefore, for example, it is possible to easily check when a transmission error occurs.

Further, when canceling the passing mode,
It can be easily released by sending data to that effect via the upper or lower network controller of the relevant network controller, so that it is possible to switch from the passing mode to the normal mode without resetting all network controllers as in the past. Can be reliably controlled.

Further, the host computer can receive reply messages from all network controllers only by transmitting one command message to the uppermost network controller. It is not necessary to transmit a command message to each of them, and since one reply message includes reply data of all the network control devices, the processing is facilitated. Therefore, it is possible to reduce the processing in the host computer and the transmission processing time.

[Brief description of the drawings]

FIG. 1 is a sequence diagram showing a communication procedure between a host computer and each C-NCU according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a communication system.

FIG. 3 is a conceptual diagram showing a connection state between a host computer and each C-NCU.

FIG. 4 is a block diagram showing a configuration of a C-NCU.

FIG. 5 is a diagram showing a normal message format;

FIG. 6 is a diagram showing a message format when transmission is normal;

FIG. 7 is a diagram showing a message format when there is an error in transmission;

FIG. 8 is a sequence diagram showing a communication procedure between a host computer and each C-NCU according to the second embodiment.

FIG. 9 is also a host computer and each C-NCU.
Diagram showing the communication procedure between

FIG. 10 is a conceptual diagram showing a data flow when emergency data occurs.

FIG. 11 is a sequence diagram showing a communication procedure between a host computer and each C-NCU according to the third embodiment.

FIG. 12 is a sequence diagram showing a communication procedure between a host computer and each C-NCU according to the fourth embodiment.

FIG. 13 shows a host computer and each C-NC.
Sequence diagram showing communication procedure between U

FIG. 14 is a sequence diagram showing a communication procedure between a host computer and each C-NCU according to the fifth embodiment.

[Explanation of symbols]

 Reference Signs List 1 center side system 2 terminal side system 3 host computer 4 first C-NCU 5 second C-NCU 6 third C-NCU 10 terminal device L telephone line network

Claims (9)

[Claims] 1. A communication system comprising: a center-side system having a plurality of network controllers connected to a host computer; and a terminal-side system having a terminal connected to the network controllers via a communication line. The plurality of network controllers are cascade-connected, and when each network controller transmits data to the host computer or another network controller, the network controller transmits the data from the host computer or another network controller. Receiving transmission result data representing a transmission result, the host computer or another network control device transmits the transmission result data to each network control device when receiving data from each network control device. A communication system characterized by the following. 2. An identification information of a transmission source is added to each of the data, and each of the network controllers determines whether or not a transmission result of the transmitted data is returned based on the identification information. The communication system according to claim 1, wherein 3. A communication system comprising: a center-side system having a plurality of network controllers connected to a host computer; and a terminal-side system having a terminal connected to the network controllers via a communication line. The plurality of network control devices are cascade-connected, and when the host computer and the highest-level network control device are not connected in a line, the highest-level network control device indicates that to a lower level. A communication system in which each network controller is notified, and each lower-level network controller continues communication between the network controllers even when receiving the notification. 4. When the host computer and the highest-level network controller are not connected to each other via a line, the network controller owns the host computer or sends the host computer transmitted from each network controller. Accumulate data to a computer, when the host computer and the highest-level network controller are connected in a line, the network controller,
4. The communication system according to claim 3, wherein data is transmitted to the host computer in the order of accumulation. 5. The communication system according to claim 4, wherein the storage of the data is performed continuously from a top network controller to a lower network controller. 6. A communication system comprising: a center-side system having a plurality of network controllers connected to a host computer; and a terminal-side system having a terminal connected to the network controllers via a communication line. The plurality of network controllers are cascaded, and each of the network controllers is
A communication system characterized in that, when data with a high degree of urgency is sent from the terminal-side system, the data is sent to the host computer with priority. 7. A communication system comprising: a center system having a plurality of network controllers connected to a host computer; and a terminal system having a terminal connected to the network controllers via a communication line. The plurality of network controllers are cascaded, and each of the network controllers is
A communication system in which, when a predetermined signal is received from the host computer or another network control device, a pass mode is set to pass data received thereafter. 8. The host computer or another network control device transmits data for canceling the pass mode to the network control device in the pass mode via a higher or lower network control device of the network control device. The communication system according to claim 7, wherein 9. A communication system comprising: a center-side system having a plurality of network controllers connected to a host computer; and a terminal-side system having a terminal connected to the network controllers via a communication line. The plurality of network controllers are cascade-connected, and the host computer transmits a command message including a command to sequentially transmit data to a lower-level network controller to a highest-level network controller,
When receiving the command message, each of the network controllers excluding the highest order and the lowest order captures the data in the message, transmits the command message to the lower level network controller, and sends the command from the lower level network controller. When a reply message is received, the data is added to its own data and transmitted to a higher-level network controller,
A communication system characterized in that the lowermost network control device, when receiving the command message, captures the data in the message and transmits a reply message with its own data added to the higher-level network controller.