JPH0652077A - Data transmission system - Google Patents

Abstract

PURPOSE:To enable two repeaters connected to a transmission line restored from an abnormal state like a short circuit, a disconnection, etc., to quickly confirm a fact that the faulty transmission line has returned to a normal state. CONSTITUTION:The address information including the transmission addresses are outputted to the remote stations 3 and the repeaters 2 from a master station 1 through the transmission lines 5. Thus the data possessed by the stations 3 which are set to serve as the talkers in response to the transmission addresses are transmitted. At the same time, the stations 3 or the station 1 which are set to serve as the listeners in response to the transmission addresses receive the data from the lines 5. The repeaters 2 detect a fact that the lines 5 have the faults. Then the repeaters 2 store the contents of these faults and also transmit the signals to the lines 5 where the faults are detected when the addresses are received from the station 1 in order to confirm the repeaters 2 of the opposite party.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system for transmitting data between a master station and a remote station or between remote stations based on an instruction from a programmable controller.

[0002]

2. Description of the Related Art As a data transmission system of this type, a master station has a data transmission memory, and one remote station serving as a talker is set for each transmission address set in the transmission memory. In addition, one or more listener stations are set including the master station. Then, when data transmission is performed from a predetermined remote station (talker) to a predetermined remote station (listener), a combination in which the remote station on the data transmission side becomes the talker and the remote station on the data reception side becomes the listener The address information including the transmission address corresponding to is output from the master station to the transmission path. Then, each remote station receives the address from the transmission path and determines whether or not the transmission address indicated by the address information sets itself as a talker or a listener. Then, the remote station determined to be set as the talker outputs the data owned by itself to the transmission path, and the remote station determined to be set to the listener receives the data output to the transmission path. . By the above operation, data transmission is performed between the master station and the remote station, and the master station aims at time sharing of the transmission path.

On the other hand, the programmable controller is provided so that data can be written to and read from the transmission memory of the master station. When data from the remote station set in the talker is written to the transmission memory, The data is read, the read data is processed, and the result is written to a predetermined talker address in the transmission memory. As a result, data is transmitted from the master station to the remote station set as the listener, and the remote station operates based on the data processed by the programmable controller.

When the number of remote stations connected to the transmission path is more than the number specified in the system, or when the communication distance of the transmission path is more than the specification, a repeater is connected to the transmission path and the repeater is connected. Another transmission path is connected to the relay. That is, this repeater shapes the signal waveform input from one transmission path to a prescribed voltage level and pulse width and outputs it to the other transmission path, and functions as a so-called buffer.

Here, the repeater has a bidirectional property, and the signal input from any of the transmission lines is shaped and output. In addition, each repeater sends a confirmation signal to the repeater connected to the same transmission line, and can obtain a response to confirm that the transmission line is properly connected. You can check whether the transmission line is in a normal state.

[0006]

However, in the conventional configuration, when a failure such as a short circuit or disconnection occurs in the transmission line connected to the repeater, and the failure point is restored to a normal state, this transmission line is restored. Since the repeater connected to sends the confirmation signal to the restored transmission line at random timing, it may not be possible to confirm that the transmission line has become normal due to collision of the confirmation signals.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make two transmission repeaters connected to a transmission line recovered from an abnormal state such as a short circuit or disconnection promptly return the transmission line to a normal state. It is to provide a data transmission system that can confirm that.

[0008]

According to the present invention, a master station having a transmission memory in which a transmission address composed of a talker address and a listener address is set, and a talker or a listener corresponding to the transmission address. A plurality of remote stations that are set to and the remote station that is set to the talker via the transmission memory to input and process the data, and the processed data is set to the listener that is set to the listener via the transmission memory. A programmable controller that outputs to a station, a transmission line that connects the master station and the remote station, and a repeater that is provided at an intermediate part of the transmission line to shape and output an input signal, and output from the master station. Through the transmission line By outputting the address information including the transmission address to the relay station and the repeater, the data owned by the remote station which is set to be a talker corresponding to the transmission address is transmitted. In the data transmission system in which the remote station or the master station, which is set to be a listener corresponding to the transmission address, receives the data from the transmission line, the repeater has a transmission line connected to the repeater. Is configured to detect that an abnormality has occurred, store the content of the abnormality, and send a signal for confirming the repeater of the other party to the transmission path where the abnormality is detected when the address is received from the master station. Is characterized by.

[0009]

When the repeater connecting the transmission lines receives a signal from one of the transmission lines connected thereto, the repeater shapes the waveform of the signal and outputs it to the other transmission line. Further, the repeater normally monitors whether or not there is a short circuit or disconnection of the transmission line.
Then, when there is no abnormality in the transmission path, the repeater sends data indicating that there is no abnormality to the master station in response to the address information periodically sent from the master station, and the repeater of the master station It is stored at a predetermined address in the transmission memory.

When an abnormality occurs in the transmission line, the repeater detects the abnormality and sends the contents of the abnormality to the master station in response to the address information periodically sent from the master station. At this time, the repeater receives the address information for its own station sent from the master station,
When a signal prompting a response is sent to the other repeater connected to the transmission line in the direction in which the abnormality is detected, and when the abnormality in the transmission line is eliminated and the normal state is reached, this signal is sent to the other side. Since it can reach the repeater and check the response, it can be confirmed that the transmission path has become normal. Therefore, in order to send a signal to confirm the repeater of the other party at the timing when the address information for the own station is received, the confirmation signal sent by the repeater connected to both sides of the transmission path does not collide and the transmission path is in a normal state promptly. You can confirm that you have returned to. Further, in response to the address information sent from the master station, the status of the transmission path can be confirmed on the master station side by sending the master station as data that the transmission path is in a normal state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the overall configuration of a control center control system using a data transmission device. Here, the control center is, for example, a large number of control units for controlling a low-voltage motor arranged in a box.

In FIG. 1, the master station 1 includes a plurality of repeaters 2a, 2b, 2c, 2d, a remote station 3 for a control center, a remote station 4 for field operation, and transmission lines 5a, 5b, 5c, 5.
It is also connected via a system bus 6 and a programmable controller 7 for controlling the entire system. The master station 1 receives the status signals sent from the repeaters 2a, 2b, 2c, 2d and the remote stations 3, 4 and sends the received status to the programmable controller 7.

In each unit of the control center 8,
A remote station 3 for control center, a multi-functional protective relay 9, and an electromagnetic contactor 10 are housed in each unit. The control center remote station 3 receives operation data sent from the master station 1 and the field operation remote station 4 via the transmission lines 5a, 5b, 5c, 5d and the repeaters 2a, 2b, 2c, 2d. At the same time, the operation data is sent to the multi-function protection relay 9. The multifunctional protection relay 9 operates the electromagnetic contactor 10 according to the given operation data to open / close the main circuit 12 of the induction motor 11 to control the start / stop of the induction motor 11. The multifunction protection relay 9 also sends the status data, the main circuit current, and the failure status data of the induction motor 11 to the control center remote station 3. Then, the control center remote station 3 transmits various data provided from the multifunctional protection relay 9 to the repeaters 2a, 2b, 2c, 2d.
And to the remote station 4 for site operation via the transmission lines 5a, 5b, 5c and 5d.

On the other hand, the remote station 4 for field operation
Is arranged in the vicinity of the induction motor 11 and transmits operation data for starting and stopping the induction motor 11 to the master station 1 and the control center remote station 3. Further, the remote station for site operation 4 turns on a lamp that displays a status signal of the induction motor 11 sent from the remote station 3 for control center.

The programmable controller 7
Exchanges data with the predetermined remote stations 2 and 3 via the master station 1 to control, monitor and protect the induction motor 11 and control the entire system.

Next, the structure of the repeater 2 will be described with reference to FIG. The repeater 2 includes a CPU 13 composed of a one-chip microcomputer, two DC data transmission units 1
4, 15 and a memory 16. As the serial data transmission units 14 and 15, UART (asynchronous serial transfer)
What has a function is used, and this is connected to the transmission line 5 via pulse transformers 17 and 18, respectively. Then, the CPU 13 receives the data from the one transmission path 5 via the pulse transformer 17 (18) and the serial data transmission unit 14 (15), and converts the voltage level and pulse width of the received signal into specified values. Then, it is sent to the other transmission line 5 through the serial data transmission unit 15 (14) and the pulse transformer 18 (17). Therefore, the repeater 2 has bidirectionality and operates as a so-called buffer that sends the data received from one transmission line 5 to the other transmission line 5. Further, the CPU 13 receives the data received by the transmission path 5 through the serial data units 14 and 15 to monitor whether there is an abnormality such as a short circuit or a disconnection of the transmission path 5, and the status is stored in the memory 16. Write. And CPU
When the predetermined address information is received from the master station 1 via the transmission line 5, the reference numeral 13 sends to the master station 1 the presence or absence of abnormality of the transmission line 5 written in the memory 16 in response to the address information. To do. Next, the configuration of the master station 1 will be described with reference to FIG.

The master station 1 is provided with a CPU 19 consisting of a one-chip microcomputer for controlling the whole operation, a serial data transmission section 20, and a memory 21 for storing an operation program of the CPU 19 and fixed data. In addition, the serial data transmission unit 20
It has a UART function and is connected to the transmission line 5 via a pulse transformer 22. This serial data transmission unit 2
0 transmits serial data to the transmission unit 5 via the pulse transformer 22 and receives serial data from the transmission line 5. The CPU 19 is connected to one input port of the dual port memory 23 that is a transmission memory, and the other input port of the dual port memory 23 is connected to the programmable controller 7 via the system bus 6. A talker area and a listener area are set in the dual port memory 23. Here, the talker area is a storage area to which an address for the master station 1 to become a talker is attached, and a storage capacity of, for example, 2 bytes is secured for each address, and a listener is provided corresponding to the address. The data to be transmitted to the remote stations 3 and 4 set to 1 are held.

On the other hand, the listener area is a storage area to which the master station 1 is attached as an listener.
A storage capacity of, for example, 2 bytes is secured for each address, and the data transmitted from the remote stations 3 and 4 and the repeater 2 set to serve as talkers for the address are held. Then, the programmable controller 7 is configured to access the dual port memory 23 via the system bus 6.

Next, the operation of the above configuration will be described with reference to the diagram showing the data flow in FIG. When the master station 1 sequentially outputs address information, data transmission is performed between the master station 1 and the remote station 3 for control center or the remote station 4 for field operation according to the address information, and the result is the dual of the master station 1. Port memory 2
3 is stored. The programmable controller 7 is the dual port memory 2 of the master station 1.
Control of the induction motor 11 based on the data stored in
Monitor and protect.

The master station 1 sends address information indicating that a predetermined repeater 2a, 2b, 2c, 2d becomes a talker to the transmission lines 5a, 5b, 5c, 5d at a predetermined timing. Then, the repeater 2 set in the talker sends data indicating the states of the connected transmission lines 5a, 5b, 5c, 5d to the transmission lines 5a, 5b, 5c, 5d in response to the address information. The master station 1 receives the data and writes it in the listener area of the dual port memory 23.

Here, if an abnormality such as a short circuit or disconnection occurs in the transmission line 5b, the repeaters 2a and 2b detect this abnormality and store the content of the abnormality in the memory 16. And
As described above, when the predetermined address information is input from the master station 1, the contents stored in the memory 16 are sent to the transmission line. As a result, the master station 1 can detect that the transmission path between the repeaters 2a and 2b is in an abnormal state. Repeater 2 that detected an abnormality
The a transmits a confirmation signal in the direction of the transmission path 5b which is in an abnormal state at the timing of receiving the address information for the own station sent from the master station 1. Transmission line 5b
Is abnormal, the confirmation signal does not reach the repeater 2b, and therefore no response is received from the repeater 2b. When the transmission line 5b is in the normal state, this confirmation signal reaches the repeater 2b via the transmission line 5b and sends a response signal to the repeater 2a. Repeater 2a is repeater 2
When the response signal from b is received, it can be confirmed that the transmission line 5b is in the normal state, and the fact that the transmission line 5b is in the normal state is sent to the address information for the own station sent from the master station 1. . Similarly, the repeater 2b also sends a confirmation signal to the transmission line 5b which is in an abnormal state at the timing when the address information for the local station is received, and monitors the state of the transmission line.

According to the above configuration, for example, when the transmission line 5b is in an abnormal state between the repeaters 2a and 2b, the repeaters 2a and 2b connected to both ends of the transmission line 5b are transmitted from the master station 1 to the own station. Since the confirmation signal is transmitted to the repeater of the other party via the transmission line 5b at the timing when the address information for the destination is received, even if the transmission line 5b returns to the normal state, the confirmation signals of the repeaters 2a and 2b do not collide with each other. A confirmation signal can be received. Therefore, the restoration state of the transmission line can be promptly detected, and the transmission line at the abnormal portion can be cut off and restored reliably, so that the failure recovery time of the entire system can be minimized.
In the above embodiment, the example in which the present invention is applied to the control center control system is shown, but the present invention may be applied to other transmission systems.

[0024]

As is apparent from the above invention, according to the data transmission system of the present invention, when an abnormality occurs in the transmission line connected to the repeater, the address information for the own station sent from the master station is received. Even if the transmission line returns to a normal state by sending a confirmation signal to the other repeater connected to the transmission line in which the abnormality occurs at the timing, the state of the transmission line does not collide with the other repeater and the confirmation signal. Can be confirmed. Therefore, since the state of the transmission path can be confirmed, the reliability of the transmission system can be improved and the system recovery time can be minimized.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an overall configuration of a transmission system using a repeater according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a repeater.

FIG. 3 is a block diagram showing the configuration of a master station.

FIG. 4 is a diagram showing a data flow.

[Explanation of symbols]

In the figure, 1 is a master station, 2a to 2d are repeaters, 3 is a remote station for control center, 4 is a remote station for field operation, 5a to 5d are transmission lines, and 7 is a programmable controller.

Claims (1)

[Claims] 1. A master station having a transmission memory in which a transmission address composed of a talker address and a listener address is set, and a plurality of remote stations set to become talkers or listeners corresponding to the transmission addresses. A programmable controller that inputs and processes data from a remote station set in the talker via the transmission memory and outputs the processed data to a remote station set in the listener via the transmission memory; A transmission line connecting between the master station and the remote station, and a repeater provided at an intermediate portion of the transmission line for waveform-shaping an input signal and outputting the waveform, the remote station from the master station through the transmission line, Lipi By outputting address information including the transmission address to the data, the data possessed by the remote station set to serve as a talker corresponding to the transmission address is transmitted, and In a data transmission system in which the remote station or the master station set to be a listener corresponding to a transmission address receives the data from the transmission line, the repeater has an abnormality in a transmission line connected to the repeater. Is detected and the contents of the abnormality are stored, and immediately after receiving the address from the master station, a signal for confirming the other repeater is transmitted to the transmission path where the abnormality is detected. A data transmission system characterized in that