JP2554940B2 - Data communication system - Google Patents

Description

The present invention relates to a data communication system, and more particularly, to a center side including a host computer, a network control device, and a data terminal side device, which are connected via a communication network. The present invention relates to a data communication system for controlling the data communication.

[Prior Art] When a data terminal device is connected to a communication network for data communication, it is necessary to set a communication path between the data terminal device and the host computer on the center side before data transmission / reception. For this reason, connection control such as activation / restoration of a central office switch, transmission of a selection signal, detection of a ringing signal, etc. is performed to set a communication path.

Generally, a plurality of data terminal devices are connected to a host computer on the center side via a communication network.
T-NCU).

Conventionally, in data communication via the T-NCU, except for a special case, when a message is sent from one side to the other side, there is usually a response to it. Therefore, the T-NCU basically treats the uplink and downlink as a pair as the communication direction of the message. An example thereof will be described with reference to FIG.

FIG. 7 is a basic protocol diagram of the T-NCU for explaining that upstream and downstream electronic messages are communicated in pairs.

In the figure, a center including a host computer and a terminal-side device including a data terminal device communicate with each other via a terminal-side network control unit (T-NCU). Assuming that the communication from the center to the device on the terminal side is "down" and the communication from the device on the terminal to the center is "up", the message direction in Fig. 7 is paired with. It always returns "up" for "down". However, in the through mode (corresponding to and in Fig. 7) in which the T-NCU communicates directly between the center and the terminal side device and the T-NCU simply passes without referring to the contents of the message, the T-NCU always goes up the message. Downlinks are not always paired. This will be described with reference to FIG.

FIG. 8 is a protocol diagram in which an upstream message error occurs even if the communication direction is switched with respect to the communication end message.

In the figure, the message direction, and correspond to an up / down pair, and in particular, and correspond to the through mode. Now, it is assumed that the telegram is an end telegram indicating the end of communication that the center sends to the terminal side device, and that the terminal side device does not return a response telegram when receiving the end telegram. Therefore, when the downlink message which is the end message is transmitted from the center to the terminal device, the uplink message is not transmitted from the terminal device to the center.

[Problems to be Solved by the Invention] As described above, the T-NCU of the conventional data communication system is used.
Operates to refer to the contents of a through message directly communicated between the center and the terminal device in the through mode without referring to the contents. Therefore, the T-NCU cannot judge whether the message sent from the center to the terminal side device is the end message in the through mode, so the response message that should not be sent by switching the communication direction even after sending the end message. A state occurs such that it waits for (the upstream message in FIG. 8).
Therefore, there is a problem that the T-NCU recognizes a response error of the terminal device in response to the fact that the response message is not transmitted, performs error processing, and consequently disconnects the communication line.

Further, in order to solve the above-mentioned problem, a method in which the T-NCU confirms the content of the through message can be considered. This will be described with reference to FIG.

FIG. 9 is a communication protocol diagram of a message storage type T-NCU.

In FIG. 9, the downlink message and the uplink message are through messages that originally pass through the T-NCU. TN
It is assumed that when the CU receives the through message, it temporarily stores the message contents inside the T-NCU, confirms the contents, and then sends the message. Therefore, the downlink message and And send it to the device on the terminal side. It is also conceivable to use a method of storing electronic messages that is then transmitted to the center. However, in this method, since the T-NCU always stores and confirms the through message, the communication time is too long. Furthermore, since the T-NCU needs to store completely unrelated telegrams inside, it is necessary to provide a storage capacity corresponding to the length of the up and down telegrams. Therefore, T
-There is a problem that the load of the NCU increases and the communication cost also increases.

Further, as another solution, there is a method in which the T-NCU constantly monitors a telegram passing through even in the through mode. This is not the method of temporarily storing the through message inside and confirming it afterwards as described above.
-The NCU does not require a storage capacity equivalent to the message length,
An extremely high-speed processing function is required. Therefore T-NCU
Must operate at high speed with a very expensive main controller. Further, as in the case of the above-mentioned through message accumulation, T
-Since the NCU needs to know the contents of the termination message in advance, the T-NCU also needs to change the specifications when the specifications of the terminal device or the like are changed and when the specifications of the termination message are changed. Therefore, there is a problem that the maintainability is poor and the maintenance cost is high.

Therefore, an object of the present invention is to transmit a message including contents such as communication completion from the center to the terminal device even when the message is transmitted and received directly between the center and the terminal device through the network control device. Accordingly, it is an object of the present invention to provide a data communication system capable of continuously performing the next communication process.

[Means for Solving the Problem] In a data communication system according to the present invention, a center and a plurality of data terminal devices are bidirectionally connected via a network control device, and the data terminal is allowed to pass through the network control device from the center. The center sends to the network control device, including the response required through message that requires a response from the data terminal device side and the response unnecessary through message that does not require a response from the data terminal device side in the through message transmitted to the device side. A data communication system for communicating by including a command message requiring a response from a network control device in a message, wherein the center connects the response unnecessary through message and the command message and transmits the message. The network control device receives the transmitted connection message and divides it into the response unnecessary through message and the command message,
It is provided with means for transmitting the divided response-free through message to the data terminal device side, decoding the divided command message and responding to the center.

[Operation] Since the data communication system according to the present invention is configured as described above, it is possible to save time for waiting for a response message from the data terminal device side for a response unnecessary through message transmitted from the center to the data terminal device side. In addition, even after the response-free through message is transmitted, the data communication between the center and the data terminal device side can be continued without disconnecting the communication line.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 6.

FIG. 1 is a system configuration diagram of a data communication system according to an embodiment of the present invention.

The data communication system shown in FIG. 1 exemplifies a telemeter system using a no ringing method.

Generally, a telemeter system is a remote meter reading or remote measurement system that measures a measurement target at a distant point with a sensor, converts the measured value into an electric signal and sends it to the center, and collects the measured values. Refers to. The center records the collected data or inputs the data to the information processing device and performs necessary processing such as data statistics and analysis. The telemeter system shown in FIG. 1 is a remote meter reading system that automatically measures and collects meter readings of electricity, gas, water, etc. from a remote location using a communication line.
This system is attracting attention as an alternative to manual meter reading due to measures such as rising labor costs and difficulty in securing labor. Although the existing subscriber telephone line is used as the communication line of this telemeter system, a no ringing system using a no ringing trunk (exchanger that does not use electric bells) is adopted.

In FIG. 1, the no-ringing type telemeter system includes a center side and a data terminal device side. The center side has a host computer 1 for performing various processes on data collected from the data terminal device side, a center side network control device (hereinafter abbreviated as C-NCU) 2, and a switching center (abbreviated as LS) connected to the center side. ) 3 is included. on the other hand,
The data terminal device side includes an LS4 connected to the terminal side, a no ringing trunk 5, a T-NCU 6, meter sensors 7 and 8 having different interface units, and a home telephone 9. Center side host computer 1 and C-NC
U2 is connected via a connecting line 10, and C-NCU2 and LS3 are connected via a telephone line 11. Further, the T-NCU 6 on the data terminal device side, the meter sensors 7 and 8 and the home telephone 9 are connected via a connection line 14, the LS4 and the T-NCU 6 are connected via a telephone line 13, and the LS4 is It is connected to the no-ringing trunk 5 via interface lines 15 and 16. Further, the center side and the data terminal device side are connected to each other via an interoffice relay line 12.

As described above, the data detected or detected by the meter sensors 7 and 8 is given to the host computer 1 via the communication network of the no ringing system.

Next, the function and configuration of the T-NCU 6 shown in FIG. 1 will be described with reference to FIG.

In FIG. 2, the T-NCU 6 performs various controls including connection switching of the meter / sensors 7 and 8 and the home telephone 9 which are connected to the outside of the device, and in parallel, controls the input / output of signals via the telephone line 13. Including the function to do. More specifically, the T-NCU 6 is a main controller 605 that controls the entire apparatus, interface circuits 606 and 607 that control input / output with the meter sensors 7 and 8, and a main controller.
A reset circuit 608 for setting the 605 to an initial state, and an oscillator circuit 6 for giving a reference clock signal for operation to the main controller 605.
09 and power supply circuit 610 are included. Further, the T-NCU 6 is equipped with a connection switching circuit 612 for switching the connection with the home telephone 9, an off-hook detection circuit 611 for detecting the hook switch operating state of the home telephone 9, and a carrier detection terminal CD, and the telephone line 13 is provided.
613 for controlling data input / output between the main controller 605 and
including. Further, the T-NCU 6 is a 16 Hz call signal detection circuit 60.
1, a rectifier circuit 602, an off-hook control circuit 603, and a PB (abbreviation of push button) transmission / reception circuit 604. The 16Hz ringing signal detection circuit 601 is a ringing signal from the center side (usually 16H
z) is detected and the detection signal is given to the main control circuit 605.

 Next, the processing operation of the above-mentioned T-NCU 6 will be described.

In the T-NCU 6 shown in FIG. 2, when a call request is issued from, for example, the meter sensors 7 and 8, the main control unit 60
5 accepts this call request via interface circuits 606 and 607. In response, main controller 605
The off-hook detection signal of the off-hook detection circuit 611 is input, and the home telephone 9 is controlled to be disconnected from the telephone line 13. More specifically, when off-hook detection circuit 611 detects that home telephone 9 is not off-hook, main controller 605 accordingly disconnects home telephone 9 from telephone line 13 by connection switching circuit 612. As a result, the output signals from the meter sensors 7 and 8 are transmitted to the home telephone 9
It can be prevented from leaking to the outside through. On the other hand, when the home telephone 9 is off-hook (during a call) when the call request is made from the meter sensors 7 and 8, the meter sensor is detected until the call state ends and it is detected that the call is not off-hook. Call requests from 7 and 8 are in a waiting state.

Then, when the selection signal output from main controller 605 is a dial pulse in response to the call request from meter sensors 7 and 8, off-hook control circuit 603 outputs "O" as many as the number.
The rectifier circuit 60
A control signal for selecting the C-NCU 2 via 2 is transmitted to the telephone line 13. If the selection signal is the PB signal, the off-hook control circuit 603 remains in the ON state, the PB transmission / reception circuit 604 transmits the dual tone signal, and selects the C-NCU2 via the rectification circuit 602. The control signal is sent to the telephone line 13.

Next, when the line link is established by the output operation of the above selection signal, the data terminal device side and the center side are connected. After that, main controller 605 starts data communication via the modem 613 in an asynchronous manner. In this case, T-NCU6
A through telegram that passes through is output to the meter sensors 7 and 8 in real time through the modem 613, the main controller 605, and the interface circuits 606 and 607.

The carrier detection terminal CD of the modem 613 is
Direction and the direction of main controller 605, signals are provided from both directions, and in response, it operates to output a carrier detection signal. For example, the circuit state changes to "ON" or "OFF" depending on whether the received signal level is within a predetermined range of the modem 613, and the carrier detection signal level is changed to "HI" according to the circuit state.
Operates so that it is set to "GH" or "LOW" and output.

Next, the function and configuration of main controller 605 in FIG. 2 will be described with reference to FIG.

In FIG. 3, a main control unit 605 is a timer counter 701 that counts in synchronization with a reference clock signal output from a transmission circuit 609, a CPU (abbreviation of central processing unit) 702, and a program executed under the control of a CPU 702. Program memory 704 to be stored in advance, data memory 703 and CPU for temporarily storing data generated during program execution in program memory 704 or data required for program execution
I / O control circuit 705 that controls input / output between the 702 and external devices
including.

FIG. 4 is a protocol diagram including two-connection telegrams of the data communication system shown in FIG.

In FIG. 4, it is assumed that the center corresponds to the host computer 1, the terminal side network control device corresponds to the T-NCU 6, and the terminal side device corresponds to the meter sensors 7 and 8. In the figure, after the up and down telegram and the transmission and reception of the host computer 1 and the T-NCU 6 are performed, the through telegram and the transmission and reception of the host computer 1 and the meter sensors 7 and 8 are performed, and then the 2-connected telegram X is the host computer. 1, the communication process ends,
It indicates that the next communication process is started by the subsequent transmission of the electronic message. The 2-connection telegram X includes a termination telegram from the host computer 1 to the meter / sensors 7 and 8 and a command telegram to the T-NCU 6, and the termination telegram is T
-It is a through message that passes through NCU6. Further, in response to the reception of the command message, the T-NCU 6 sends a response message to the host computer 1. The two-link telegram X transmitted at the end of communication will be described with reference to FIG.

FIG. 5 is a diagram illustrating the configuration of the two-link telegram X according to the embodiment of the present invention.

In the figure, the two-connection telegram X includes a telegram to the meter sensors 7 and 8 in the first half, and a command telegram to the T-NCU 6 in the latter half. Each message includes a mark M, a space S, and data D representing a control command and data. Therefore, the T-NCU 6 can determine whether the received message is the through message or the command message by detecting the constant repeated pattern of the mark M and the space S. Therefore, the first half of the two-connected message X is an extension of the through mode and the meter sensor is used. It is possible to pass through to 7 and 8 and interpret the latter half as a command message to the T-NCU 6.

FIG. 6 is a flow chart showing a processing procedure of the two-connection telegram X shown in FIG.

The processing flow shown in the figure shows a procedure for determining whether or not the downlink message from the host computer 1 is the two-connection message X when the T-NCU 6 is in the through mode. This processing flow is stored in the program memory 704 in advance as a program and executed under the control of the CPU 702.

Next, the processing procedure of the two-link message of the T-NCU 6 of FIG. 6 will be described with reference to FIGS. 1 to 6. It is assumed that the transmission control procedure is determined in advance between the devices.

First, in step S1 (abbreviated as S1 in the figure), CP
The U702 confirms that the transmitted / received message is in the procedure of the through message in FIG. By this confirmation,
It is possible to determine whether it is currently in through mode. That is, the fifth
The configuration of the through message in the figure is detected twice in succession, and 3
If it is determined that the received message for the first time starts with the through message, the process proceeds to the next step S2, and the end space S of the through message (section A in FIG. 5) is searched. However, if it is determined that the T-NCU 6 is not in the through mode, it is supposed that the T-NCU 6 is in the procedure of the message to be decoded (such as the message in FIG. 4). .

In step S2, the space S (section A in FIG. 5) at the end of the through message is searched. In this case, if it is not the space S, the process proceeds to step S3, the current through mode process is continued, the process returns to step S1 through other processes, for example, the signal process of the off-hook detection circuit 611 of the home telephone 9, and the subsequent processes. Repeat. On the other hand, if the space S is detected, the process proceeds to the next step S4, where the space S in the A section is the time.
Ta (for example, Ta: 90 msec) or more continues, message space S
Wait for completion (point B in FIG. 5). Duration of space S
Ta is stored in the data memory 703 in advance. The CPU 702 compares the time Ta in the data memory 703 with the time measurement data of the timer counter 701, and when the time measurement data is equal to the time Ta, the completion point B of the space S of the through message is detected. The process moves from step S4 to step S5. In step S5, in accordance with the detection of the completion point B of the through message, it is determined whether the latter half of the message follows the through message. The process of determining the end of the message is performed by main controller 605 based on the signal level of the carrier detection signal provided from carrier detection terminal CD. For example, when the signal level of the carrier detection signal changes to the “HIGH” level, it is possible to determine that the telegram has ended, that is, the latter half of the telegram will not continue. When the latter half of the telegram, that is, the command telegram to the T-NCU6 continues, the point B is reached at the same time as the end of the space S in the section A
Can be identified by continuing the mark M of the next message.
Therefore, whether or not the latter message follows the through message,
It can be determined by whether or not the mark M immediately after the through message is detected or whether or not the signal level of the carrier detection signal changes to the “HIGH” level. If there is no signal change of the carrier detection signal as described above and the mark M is detected, the command message to the T-NCU 6 follows the through message, so the T-NCU 6 decodes the content of the command message to be received. The process moves to the next step S6 so as to continue the processing. Also step
If the carrier detection signal level changes to "HIGH" in S5, the command message does not follow the through message, so the process moves to the next step S7 depending on the end of the through message. Step
In S7, the upper and lower communication directions are switched by the end of the through message, and the message to be transmitted next is processed.

With the above procedure, it is possible to process the two-connected telegram X of the through telegram and the command telegram to the T-NCU 6. Therefore, by the process using the two-link message X, the T-NCU 6 can decode the command message following the through message in the through mode, and is released from the waiting state for the upstream message from the data terminal side after the end message is transmitted. Therefore, it is possible to smoothly shift to the next communication processing according to the command message without disconnecting the communication line.

In the present embodiment, only the end telegram is shown as the through telegram that does not require the upstream telegram (response) from the data terminal side to the host computer 1, but it is not limited to this and the meter reading command for the meter sensors 7 and 8 is not specified. Message of
It may be a telegram of a telephone number setting command relating to the home telephone 9, a time setting command telegram, a valve shutoff / opening command relating to water / gas or a flow rate limiting command and a security information reading command.

[Effects of the Invention] As described above, according to the present invention, the waiting time for the response message from the data terminal device side to the response-free through message transmitted from the center can be saved, and the data communication can be performed without disconnecting the communication line. Processing can continue. Therefore, the communication time can be shortened. Further, since the network control device may be an inexpensive main control device, it is excellent in economic efficiency. Furthermore, since the network control device does not need to know the format of the response-free through message in advance, there is no need to change the specifications accompanying the changes in the specifications of the data terminal device side, etc., and the maintenance cost of the communication system is reduced. There is an effect such as being able to.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a data communication system according to an embodiment of the present invention. FIG. 2 is a T-NCU shown in FIG.
It is a figure which shows the function structure of. FIG. 3 is a diagram showing a functional configuration of the main control device shown in FIG. FIG. 4 is a protocol diagram showing the data communication system 2 connection message shown in FIG. FIG. 5 is a diagram for explaining the configuration of a two-link message according to one embodiment of the present invention. FIG. 6 is a flow chart showing a processing procedure of the two-connection telegram shown in FIG. FIG. 7 shows T for explaining that the up and down telegrams are communicated in pairs.
FIG. 3 is a basic protocol diagram of NCU. FIG. 8 is a protocol diagram in which an upstream message error occurs even if the communication direction is switched with respect to the communication end message. FIG. 9 shows a T-NCU of the electronic message storage type.
3 is a communication protocol diagram of FIG. In the figure, 1 is a host computer, 6 is a terminal side network control unit (T-NCU), 7 and 8 are meter sensors, 605 is a main control unit and X is a two-link telegram. In each drawing, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. A center and a plurality of data terminal devices are bidirectionally connected via a network control device, and a through message sent from the center through the network control device to the data terminal device side is transmitted from the data terminal device side. A command that requires a response from the network control device to the message sent to the network control device by the center, including a response-necessary through message that requires a response and a response-free through message that does not require a response from the data terminal device side. A data communication system including a message, wherein the center includes a connection message transmitting unit that connects and transmits the response-free through message and the command message, and the network control device transmits the transmitted message. A concatenated telegram is received and divided into the response unnecessary through message and the command message, and the divided response unnecessary through message is transmitted to the data terminal device side and divided. Comprising means for responding to the center decodes the command telegram, the data communication system. 2. The data communication system according to claim 1, wherein the concatenated message includes a predetermined repeating pattern of marks and spaces.