JPH11261615A - Double loop type data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a double loop type data transmitter that requires neither an exclusive line control protocol nor an exclusive check frame attended therewith. SOLUTION: Plural transmission stations are connected by double loop transmission lines, each transmission station acquires a right sequentially and sends data. Each transmission station sends a same frame to the double transmission lines in opposite directions at the same time, when acquiring a right, a reception station repeats frames received from both the directions to opposite adjacent stations to adjacent stations from which the frames are received and selects a frame which comes first in this system. In this case, the transmitter is composed of a repeat code addition circuit 10 that adds a code denoting the repeat to the end of the frame, a field detection circut 5 that detects the repeat code in a reception circuit, whether or not a received frame has a repeated frame, or detects a frame of a designated transmission source station address and a circuit 9 that latches a transmission source address included in the frame at that time and the detection result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-loop data transmission apparatus in which a plurality of transmission stations are connected by a double-loop transmission path, and each transmission station sequentially acquires a transmission right and transmits data. About.

[0002]

2. Description of the Related Art As a conventional data transmission device, the shape of a transmission line 51 connecting a plurality of transmission stations 50 can be roughly divided into a bus type shown in FIG. 5A and a bus type shown in FIG. There are two types of loop type shown.

In the bus type, since a plurality of transmission stations 50 are connected to a common transmission line 51, an electric medium is used, and the bus type is applied to a relatively short-distance system due to the limitation of drive capacity. While it is easy to add and delete the transmission station 50, the transmission path 5
In the event that a failure occurs in one, there is a disadvantage that the entire system cannot communicate.

[0004] The loop type is suitable for optical communication because a plurality of transmission stations 50 are connected to a loop-shaped transmission path 51 and the direction of the signal flow is suitable. The signal is reproduced by the transmission station 50. Therefore, it is suitable for relatively long-distance systems. Further, there is a weak point that if there is a failure on the loop transmission line due to the directionality, the signal is interrupted there.

[0005] Regarding this, a loop-back system in which a transmission path is duplicated and a signal is looped back at a station before and after a failure point, or a transmitting station transmits the same data to a double transmission path in the opposite direction. And a simultaneous transmission / selection reception method in which the receiving station selects and receives one of the data circulating in opposite directions.

In a transmission device, it is very important to recognize its physical arrangement (connection order) and the state of communication with neighboring stations. This is because it is possible to specify an abnormal location on a physical system by matching the failure state described above.

[0007] In the case of the bus type transmission line shown in FIG.
Since each transmission station is directly electrically connected to the common 50 trunk line, the physical arrangement cannot be theoretically recognized. In the transmission device of the loop type shown in FIG. 5B, the following methods (1) and (2) are used as a method of recognizing the physical arrangement.

(1) A method of giving physical configuration information to a transmission station in advance. (2) A method of preparing a check frame for a neighbor station. In the method (2), as shown in FIG. 6, a check frame (state confirmation frame) 50a for state confirmation dedicated to the neighboring transmission station 50 is prepared at the line control level, and each transmission station 50 In this state confirmation frame 50a
Is transmitted to a neighboring station, and the receiving station returns a response frame 50b including its own address using the opposite transmission line without repeating this frame. In this case, the status confirmation frame 50a and the response frame 50b are both obtained by adding a special protocol to a normal protocol.

In the case of a loop-type transmission device, there is generally a specific station having a function of monitoring a transmission line for abnormality and reconfiguring the line. When the above-mentioned simultaneous transmission / selection reception method is adopted, the transmitted signal is repeated at each station and circulates. However, there are stations that terminate the signal in order to prevent the signal from infinitely circulating. This station cuts the transmission line to prevent this infinite loop when the loop is formed normally. However, when a failure occurs in the transmission line, the station repeats the signal to secure the communication path.

As a method of detecting this abnormality, a method in which the transmitting station that has detected the adjacent station abnormality notifies the terminal station of a signal of a specific pattern, or a method of transmitting a dedicated notification frame to notify the terminal station,
The specially configured terminal station itself transmits a dedicated round check frame to both transmission lines, and detects a failure on the transmission line based on whether or not it has returned once.

[0011] In these transmission devices, a test program for a single module is usually provided in the firmware software of the station for product testing or on-site confirmation, and a switch or a tool on the module is designated. They are turning themselves back.

[0012]

The conventional apparatus having the above configuration has the following problems.
In the above-mentioned method in which the physical arrangement is given as configuration information in advance, there is a risk of erroneous input by a human system. There is the inconvenience of having to do it.

[0013] Adding the dedicated status confirmation frame 50a to the line control level protocol requires a great deal of software and hardware creation. Will be affected.

And a switch on the aforementioned module,
Alternatively, in the method in which self-returning is performed by designating tools, since switches or tools are manually designated, there is a risk of forgetting to return the settings, and setting itself at the time of a test is difficult.

An object of the present invention is to provide a current system configuration by checking a received data frame without requiring a dedicated line control protocol and a dedicated check frame associated therewith. It is an object of the present invention to provide a double-loop data transmission device which can be detected at high speed without using a dedicated command frame, can be implemented without using a dedicated command frame, and can reduce the human error and simplify the operation itself.

[0016]

In order to achieve the above object, according to the first aspect of the present invention, a plurality of transmission stations are connected by a double loop transmission path, and each transmission station assigns a transmission right in order. A transmission device for acquiring and transmitting data, wherein the transmitting station simultaneously transmits the same frame to each of the dual transmission paths in the opposite direction when acquiring the transmission right, and the receiving station transmits the data from both directions. In a double-loop data transmission device that repeats a received frame by a neighboring station repeater circuit opposite to the neighboring station that transmitted the frame and selects a frame that has been received first, a frame from the repeat circuit A repeat code adding circuit for adding a code indicating that the signal has been repeated, and a repeat code added by the repeat code adding circuit being added to a frame received by a receiving circuit. An address of a neighboring station, comprising: a detection circuit for detecting whether or not the frame has a designated source station address; and a circuit for latching a detection result by the detection circuit and a source address included in the frame at that time. This is a double loop type data transmission device provided with a neighbor address determining means for determining the data transmission.

In order to achieve the above object, a second aspect of the present invention is to collect neighbor station information of each station including an address obtained by the neighbor station address determination means.
2. The double-loop data transmission device according to claim 1, wherein a connection configuration of transmission stations of the transmission system can be created.

In order to achieve the above object, the invention according to claim 3 uses the neighbor station address determining means to determine that the transmission cable is in a loopback state because the neighbor station is the own station. The double-loop data transmission device according to claim 1, wherein the automatic loopback test can be performed by making a determination.

According to a fourth aspect of the present invention, in order to avoid the infinite loop of a signal when the transmission path of the double loop is normal, a disconnection of the transmission medium is performed. When an error occurs in the transmission line due to power interruption of the transmission station or the like, the termination of the transmission line is stopped, and a signal termination station having a function of maintaining communication between the stations by performing the repeat operation is used. 2. A neighbor station address judging means for simultaneously transmitting a frame to a system and detecting, by the detection circuit, whether the transmission line is normal or not based on whether the frame is received via a loop transmission line. It is a double-loop data transmission device as described.

According to the invention corresponding to any one of the first to fourth aspects, the following operation and effect can be obtained. In particular, the current system configuration can be obtained by checking the received data frame without requiring a dedicated line control protocol and a dedicated check frame accompanying the line control protocol. In addition, the terminal station itself can detect at high speed, and is realized without using a dedicated command frame. Further, by detecting that the transmission cable is turned back to its own station and automatically executing a unit test, the mistakes in human systems are reduced and the operation itself is simplified.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing only a main part of an embodiment of a double-loop data transmission device according to the present invention. The above-described conventional data transmission device is configured as follows. That is, the signal received from the transmission path in FIG. 1 is converted into an electric signal by the optical receiver 1 and then code-converted from the transmission code to the NRZ code by the decoder 2. Conventionally, this converted signal is repeated from the transmission circuit via a FIFO circuit for synchronizing with the transmission timing, and the signal passing through the FIFO is simultaneously taken into the station.

In the embodiment of the present invention, a repeat code detecting means (neighbor station address determining means) 4 enclosed by a dashed line described below is newly provided between the decoder 2 and the FIFO circuit 3 in FIG. This will be described below.

The signal received from the transmission line is transmitted to the optical receiver 1
Is converted into an electric signal.
Receiving the received data converted to the RZ code and a reception clock for providing the synchronization timing thereof, each field (source address) constituting the reception frame is identified, and when identification is possible, a field identification signal 5a is output. A field detection circuit 5 for detecting whether or not a repeat code is attached after the frame from the received data and the received clock, and outputting a repeat code detection signal 6a if the repeat code can be detected; 6, a shift register 7 for converting serial received data into parallel data, an address latch circuit 9 for storing a source station address from the parallelized data as a signal from a timing generation circuit 8 described later, Repeat code adding circuit 10 for adding a repeat code at the end of a frame , And a gate 39 for adding the repeat code from the repeat code additional circuitry 10 to the data of the shift register 7 outputs.

The field identification signal 5a from the field detection circuit 5, the repeat code detection signal 6a from the repeat code detection circuit 6, the source station address in the reception frame latched by the address latch circuit 9, and And an upper CPU (upper CPU) 3 in FIG.
2 from the detection condition given via output port 13 to be described later via internal bus 11 and address latch timing signal 8c and repeat code addition timing signal 8d
And a timing generation circuit 8 for outputting a detection completion signal to an input port 12 described later.

Further, by connecting to the internal bus 11,
An input port 12 and an output port 13 for interfacing between the U32 and the repeat code detecting means 4 are provided.
In this case, the data to be transmitted is communicated in the form of a frame. The frame referred to here is a flag field indicating the start and end of the frame, a destination address field, a type field indicating the frame type, a source address field, a length field indicating the length of the frame, a data field for storing data, and An error detection field for storing an error detection code for detecting a data abnormality on the transmission path is included.

FIG. 2 shows an example of the frame format, which comprises a flag, a destination address, a frame type, a source address, a frame length, data, an error detection code, and a flag.

The repeat code detecting means 4 constructed as described above operates as follows. The electric signal from the optical receiver 1 receives the reception signal converted into the NRZ signal by the decoder 2, and the field detection circuit 5 detects the flag pattern of the frame, detects each subsequent field position, and performs the field identification. The signal 5a is output to the timing generation circuit 8.

The repeat code detecting circuit 6 detects whether or not there is a repeat code (not shown) after the last flag of the frame shown in FIG. 2, and notifies a repeat code detection signal 6a to the timing generating circuit 8 as well. The timing generation circuit 8 outputs an address latch timing signal 8c from the field identification signal 5a and stores the contents of the source address field in the frame from the shift register 7 to the address latch circuit 9. Also, the end of the frame is detected, and a repeat code addition timing signal 8d is output to the repeat code addition circuit 10 to add a repeat code after the received frame. The detection condition is given from the host CPU 32 to the timing generation circuit 8 via the output port 13.

The detection condition is such that detection of a frame with / without a repeat code and detection of a specific source address can be selected as conditions for stopping the detection operation. When the detection condition is given, the timing generation circuit 8 starts detection. When the detection condition is found, the timing generation circuit 8 stops the detection operation and outputs a detection completion signal to the input port 12. For example, given the condition of detecting a frame without a repeat code,
The timing generation circuit 8 monitors a frame received from the field identification signal 5a and the repeat code detection signal 6a, and outputs a detection completion signal when a frame without a repeat code is found, and thereafter stops taking in the address latch. I do.

The upper CPU 32 periodically checks the input port 12, and when the detection is completed, reads the address value at that time to recognize the address of the adjacent station. If the detected address of the adjacent station matches the address of the own station, it is known that the transmission and reception of the own station are directly connected, and it can be determined that the configuration is a unit test configuration.

If the detection is made with the detection condition set to the station address of the own station, it means that the frame transmitted from the own station has returned after making a round of the transmission path, and the loop transmission path 14
A and 14B are in a normal state. By the above method, each transmission station can know the station number of the neighboring station. By collecting this, the physical location of the entire station can be known.

FIG. 3 shows a system configuration of the embodiment. Each of the transmission stations (1), (2)... (N) 40 is connected in a loop by double transmission lines 14A and 14B of A system and B system, and data is transmitted in the direction of the arrow in the figure. And For convenience, the data transmission side is defined as upstream and the data transmission side is defined as downstream, considering the signal flow of the A system as a reference.

When viewed from the transmission station (2) 40 in FIG. 3, the transmission station (1) 40 is on the upstream side, and the transmission station (3) 40 is on the downstream side. Therefore, the transmission station (2) 40 transmits the transmission station (1) to the transmission station (3) 40 on the A-system transmission line 14A during transmission.
The data is transmitted to the transmission stations (1) 40, (3) 4 through the B-system transmission path 14B, and the data loops through the loop.
Come back via 0.

FIG. 4 shows the internal configuration of two adjacent transmission stations 40 out of the plurality of transmission stations 40. The transmitting and receiving unit includes an optical transmitter 16a for transmitting the optical transmission signal 15a to the downstream transmission station via the A-system transmission path 14A, an encoder 17a for changing the transmission signal 38a of the NRZ code to the transmission code 25a, and a reception signal from the upstream. A transmission signal selecting circuit 23a for selecting a signal to be transmitted from a check signal 20a from the adjacent station failure detecting circuit 19a for monitoring the line state between the station 18a and the downstream station and a transmission data signal 22 of the own station from the transmission controller 21, An optical receiver 35b for receiving the B-system optical signal 24b from the station, and an electric signal 3 from the optical receiver 35b
6b to a NRZ code 26b, a repeat code detection circuit 28b for receiving a NRZ code 26b from the decoder 27b and detecting a repeat code, and temporarily storing a received signal 37b of the repeat code detection circuit 28b for internal synchronization timing. FIFO for tuning with
It comprises a circuit 29b and an adjacent station fault detecting circuit 19a which monitors the received signal 18b and transmits a check signal 20a to monitor the connection state of the downstream adjacent station.

The above configuration is the same on the upstream side, and the optical transmitter 16b, the encoder 17b, the transmission signal selection circuit 23b,
Neighbor station failure detection circuit 19b, optical receiver 35a, decoder 2
7a, a repeat code detection circuit 28a is provided.

In addition, a FIFO circuit 29 for both A / B systems
b, a reception selection circuit 31 which gives a reception signal to the transmission controller 21 with priority given to a first-arrived signal, a transmission controller 21 which transmits and receives transmission / reception data to / from the upper CPU 32, and an internal bus 33 And a memory 34 for storing programs and transmission data of the host CPU 32 for controlling these transmission circuits via the CPU.

The repeat code detecting circuits 28b and 28
a, the adjacent station fault detection circuits 19a and 19b, and the transmission controller 21 are connected to the host CPU 32 via an internal bus 33, and receive software control thereof.

Next, the operation of the embodiment having such a configuration will be described. First, a general operation will be described. In the case of the own station transmission, the upper CPU 32 creates a frame including the transmission data and passes it to the transmission controller 21. When the transmission controller 21 acquires the transmission right, it outputs a transmission signal 22 to both A / B transmission lines. This transmission signal 22 is transmitted to transmission signal selection circuits 23a and 23b,
The signals are output to the transmission lines of both systems via the optical transmitters 7a and 17b and the optical transmitters 16a and 16b. In the case of reception, the signal 24b received from the system B is supplied to the decoder 27b and the repeat code detection circuit 2.
8b, via the FIFO circuit 29b, one is passed to the reception selection circuit 31, and the data of the first-arrived system is transmitted to the transmission controller 2
1 and stored in the memory 34 by the upper CPU 32.

The output signal 30b of the FIFO circuit 29b is
The signal is also transmitted to the transmission signal selection circuit 23b on the upstream side, is repeated, and is transmitted from the B-system transmission line to the upstream station. In addition to data transmission / reception, the transmission station needs to monitor the state of communication with the upstream / downstream transmission station and prohibit communication with the transmission station in the abnormal direction when an abnormality is detected.

Therefore, the adjacent station fault detection circuits 19b and 1b
9a monitors the reception status from the upstream / downstream, respectively.
When a no-signal state is detected for a certain period of time, the check signal 20a,
20b.

When the power is turned on, the transmission station 40 initializes an internal circuit. When the initialization is completed normally, both systems wait for a certain period of time in a state where transmission is prohibited and reception is permitted to recognize the state of the system. If a normal data frame is received during this time, the system has already been started up and enters the system entry mode.

When the transmission station 40 does not receive the data for a certain period of time or longer, the upper CPU 32 sets the adjacent station fault detection circuits 19a, 19b
, A survival signal indicating the start of the transmission station is sent to the upstream / downstream transmission path, and the survival signal similarly sent from the adjacent station is monitored and waits until the next station starts.

The transmission station 40, which is not the signal terminal station, waits for the system invitation from the signal terminal station upon detecting the survival signal from the neighboring station. If there is no system invitation for a sufficiently long time, the repeat code detection circuit 28a, The detection of a frame without a repeat code is designated to the output port 28b, a frame for checking is transmitted from the transmission controller 21, and the input ports of the repeat code detection circuits 28a and 28b are periodically monitored.

If the source address of the frame without repeat code detected on the transmission path of both systems matches the own station address, the adjacent station is the own station itself, and the upstream connector and the downstream connector of the own station are used. It can be seen that the connectors are directly connected. As a result, it is determined that the connection is the transmission path connection of the own station and the apparatus enters a mode in which the own station return test is performed.
In the case of the signal terminal station, when a surviving signal from the neighboring station is detected, the repeat code detection circuit 28b is instructed to detect the frame of the own station address, and transmits a check frame to the transmission paths of both systems.

As a result, when the frame of the own station address is returned with the repeat code, it can be determined that the transmission line of the system is normal, and the operation shifts to the system configuration operation.
If the frame of the own station address is returned without the repeat mode, it is determined that the neighboring station is the own station itself and the transmission path connection for the own station is returned, and the mode for executing the own station return test is entered. As described above, since it is possible to determine that the transmission path connection is for the return of the own station, it is possible to determine the adjacent station without any designation from the switch or the outside.

If the frame of the own station address cannot be detected, it is determined that there is an abnormality in the loop transmission path, the signal termination is stopped, the signal is repeated, and the system configuration operation is started. The detection of the loop state can be performed by periodically performing this detection even after the system operation starts. When the system starts up normally and transmission starts, each transmission station specifies the detection of a frame without a repeat code to the repeat code detection circuits 28a and 28b, and recognizes the address of the adjacent station. This allows each station to know the addresses of the transmission stations on both sides. Further, by collecting this information, the physical arrangement of the transmission stations in the entire system can be known.

According to the above-described embodiment, by adding the repeat code detecting means 4, the address of the adjacent station can be detected, and the physical arrangement of the transmission station in the entire system can be known from the information. Also, since the connection state of the transmission line can be determined from the connection state of the transmission line to be the loopback connection of the own station, a special test switch can be provided to automatically perform the unit test of the transmission station without specifying it. it can. Further, the signal terminal station can know the state of the loop transmission path.

[0048]

According to the present invention described above, the current system configuration can be obtained by checking received data frames without the need for a dedicated line control protocol and a dedicated check frame associated therewith. A double-loop data transmission device that can be detected at high speed by the terminal station itself, can be realized without using a dedicated command frame, and can reduce errors in human systems and simplify the operation itself. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing only a main part of an embodiment of a double-loop data transmission device according to the present invention.

FIG. 2 is a view showing an example of the frame format shown in FIG. 1;

FIG. 3 is a diagram showing a system configuration according to the embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of adjacent transmission stations in FIG. 3;

FIG. 5 is a diagram for explaining a form of a transmission path of a conventional data transmission device.

FIG. 6 is a diagram for explaining a problem of a conventional data transmission device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical receiver, 2 ... Decoder, 3 ... FIFO circuit, 4 ...
Repeat code detection means, 5 ... Filled detection circuit, 6 ...
Repeat code detection circuit, 7 shift register, 8 timing generation circuit, 9 address latch circuit, 10 repeat code addition circuit, 11 internal bus, 12 internal bus, 13 output port, 39 or gate.

Claims (4)

[Claims] 1. A transmission apparatus in which a plurality of transmission stations are connected by a double loop transmission path, and each transmission station acquires a transmission right in order and transmits data. When the right is acquired, the same frame is simultaneously transmitted in the opposite direction to each of the double transmission lines, and the receiving station transmits the frame received from both directions by the neighboring station repeater circuit opposite to the neighboring station that transmitted the frame. In a double-loop data transmission device that adopts a method of selecting a frame received first while receiving a repeat, a repeat code addition circuit that adds a code indicating that the frame has been repeated to the frame from the repeat circuit, It is detected whether or not the repeat code added by the repeat code adding circuit is added to the frame, or whether the frame is the frame of the specified source station address. And a circuit for latching the result of detection by the detection circuit and a source address included in the frame at that time. apparatus. 2. The duplex system according to claim 1, wherein the connection configuration of the transmission stations of the transmission system can be created by collecting the neighbor information of each station including the address obtained by said neighbor address determination means. Loop type data transmission device. 3. Using the neighbor station address determination means,
The double-loop data transmission device according to claim 1, wherein an automatic loopback test can be performed by determining that the transmission cable is in a loopback state of the local station since the neighboring station is the local station. 4. When the transmission path of the double loop is normal, the signal is terminated in order to avoid an infinite loop of the signal, and an abnormality occurs in the transmission path due to disconnection of the transmission medium or power supply of a transmission station. In this case, at the signal terminal station having the function of holding the communication between the stations by stopping the end of the transmission line and performing the repeat, the frame is simultaneously transmitted to both systems of the transmission line, and the detection circuit 2. The double-loop data transmission apparatus according to claim 1, further comprising a neighbor address determining means for detecting whether or not the transmission path is normal depending on whether the signal is received via the loop transmission path.