JP2000059411A - Communication line changeover device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily specify a fault occurrence position on the occurrence of a fault and to allow a normal slave communication device to send/receive communication data on the occurrence of the fault by controlling connection switching of a connection section and a communication output of a driver. SOLUTION: On the occurrence of a broken line in a communication path 5c, since the input signal to a communication processing section 11C of a slave communication device 1C is interrupted, the communication processing section 11C detects the broken line and transmits a broken line detection signal to a master communication device 2. A changeover control section 12 of the master communication device 2 and changeover control sections 12A-12C of slave communication devices 1A-1C close connection sections 10, 10A-10C and stop outputs of drivers 31, 31A-31C at the same time, after confirming no signal in the communication path. Then the slave communication devices 1A, 1B receive communication data and output reply data with respect to communication data output from the master communication device 2 to the slave communication devices 1A-1C, but the slave communication device 1C does not output reply data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication path switching apparatus for connecting a plurality of slave communication apparatuses to a master communication apparatus by using an electrically looped communication path.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing an example of a communication device for connecting a plurality of slave communication devices to a conventional master communication device by using an electrically looped communication path.
The communication data output from the main control unit 21 of the master communication device 2 is input to the communication processing unit 11A via the driver 31, the connection cable 4A, the receiver 32A of the slave communication device 1A, and the communication path 5A. The communication processing unit 11A exchanges necessary data and outputs communication data to a subsequent communication device. Similarly, the communication data output from the communication processing unit 11A of the slave communication device 1A includes the communication path 6A, the driver 31A, the connection cable 4B, and the slave communication device 1B.
Communication processing unit 1 via the receiver 32B and the communication path 5B
1B. The communication processing unit 11B exchanges necessary data and outputs communication data to a communication device at a subsequent stage. Similarly, the communication processing unit 1 of the slave communication device 1B
The communication data output from the communication path 6B, the driver 3
1B, the connection cable 4C, the receiver 32C of the slave communication device 1C, and the communication path 11C to be input to the communication processing unit 11C. The communication processing unit 11C exchanges necessary data and outputs communication data to a subsequent communication device. Similarly, the communication processing unit 11C of the slave communication device 1C
The communication data output from the communication path 6C and the driver 31
C, connection cable 4D, receiver 3 of master communication device 2
2, a communication path is input to the main control unit 21 and a signal is connected to form a loop.

Here, an example of data of each connection cable is shown in FIGS. The master communication device 2 is shown in FIG.
As shown in (A), the slave communication devices 1A, 1B, 1C
Are output at certain time intervals (data of the connection cable 4A). The slave communication device 1A receives the data A1 addressed to its own slave communication device, outputs data a1 as a response as shown in FIG. 5B, and outputs the data B1 and data C1 addressed to the other slave communication devices as they are ( Data of connection cable 4B). Note that the time difference between the data of the connection cable 4A and the data of the connection cable 4B indicates a delay due to the processing time in the slave communication device 1A. The slave communication device 1B stores data B1 addressed to its own slave communication device.
, And as a response, as shown in FIG.
1 and the data a1 from the other slave communication device and the data C1 to the other slave communication device are output as they are (data of the connection cable 4C). In addition, connection cable 4
The time difference between the data of B and the data of connection cable 4C is
This shows a delay due to the processing time in the slave communication device 1B. The slave communication device 1C receives the data C1 addressed to its own slave communication device, outputs data c1 as a response as shown in FIG. 5D, and outputs data a1 and data b1 from other slave communication devices as they are ( Data of connection cable 4D). Note that the time difference between the data of the connection cable 4C and the data of the connection cable 4D indicates a delay due to the processing time in the slave communication device 1C. Similarly, data A2 and data B2 are sequentially output from the master communication device 2, and a series of transmission and reception of these communication data is continuously performed at a certain time interval. In this example, the description is for a case where there are three slave communication devices. However, even if the number of slave communication devices to be connected is increased or decreased, the slave communication devices can be similarly connected and operated.

[0004]

In a communication apparatus in which a plurality of slave communication apparatuses are electrically connected to a conventional master communication apparatus by using a loop-shaped communication path, when a failure occurs in a part of the communication path, a communication path is established. Is shut off. For example, when a disconnection occurs in the connection cable 4A or the communication path 5A in FIG. 4, the communication processing unit 11A of the slave communication device 1A detects the disconnection and transmits a disconnection detection to the main control unit 21 of the master communication device 2. Thus, it can be specified that the disconnection point is the connection cable 4A or the communication path 5A. Similarly, when the slave communication device 1B detects the disconnection, the communication path 6A or the connection cable 4B or the communication path 5B. When the slave communication device 1C detects the disconnection, the communication path 6B or the connection cable 4C or the communication path 5C. , Master communication device 2
If the disconnection is detected, the communication path 6C or the connection cable 4
D indicates that the wire is disconnected.

However, in any of the above cases, there is a problem that only the disconnection section can be confirmed, and no further disconnection location can be specified. Further, since each slave communication device stops the control of each slave communication device when it confirms that there is no signal on the communication path from the preceding stage, the control of the normal slave communication device also stops. Therefore, if the series of processing performed so far is wasted, or if the slave communication device is processing the operation of the actuator, even if the control target of the normal slave communication device stops at the dangerous place, However, there is a problem that it is not possible to evacuate to a safe place until the vehicle is restored.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. The present invention makes it easy to specify the location of a failure when a failure occurs, and a normal slave communication device transmits communication data when a failure occurs. An object of the present invention is to provide a communication path switching device of a communication device that enables control by transmitting and receiving, and that connects a plurality of slave communication devices to a master communication device electrically using a loop communication path.

[0007]

According to the present invention, a master communication device having a driver and a receiver, and a plurality of slave communication devices are connected to a receiver of another communication device with the driver, and the master communication device is connected to the master communication device. The present invention relates to a communication path switching device of a communication apparatus that electrically connects the plurality of slave communication apparatuses using a communication path in a loop shape, and an object of the present invention is to connect an output of the driver to an input of the receiver. This is achieved by providing a connection unit that performs connection switching and a switching control unit that controls connection switching of the connection unit and communication output of the driver.

The switching control section switches the connection section according to the presence or absence of an output signal from the preceding stage, and controls the communication output of the driver, so that the switching control section responds to a command from the master communication device. Switch the part,
It is more effectively achieved by controlling the communication output of the driver. Further, the connection unit of the slave communication device is always closed before power is turned on, and the switching control unit of the slave communication device performs a self-diagnosis when the power is turned on, so that communication can be performed normally. The above object is also achieved by switching the connection unit of the slave communication device only when it is determined that

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a communication path switching apparatus for connecting a plurality of slave communication apparatuses to a master communication apparatus of the present invention using an electrically looped communication path. The functions and processes indicated by the same notations as those in FIG. 4 showing the related art are the same, and a description thereof will be partially omitted. In the present invention, a switching control unit 12 and a connection unit 10 are newly provided in the master communication device 2, and each of the slave communication devices 1
A, a new switching control unit 12A in each of 1B and 1C,
12B, 12C and connection parts 10A, 10B, 10C are provided. In a normal state, the connection portions in the master communication device 2 and the slave communication devices 1A, 1B, and 1C are open, and the connection cables 4A, 4B, 4C,
As shown in the normal data in FIG. 5, each data of 4D is a slave communication device 1A from the master communication device 2,
In response to the communication data output to 1B and 1C, each of the slave communication devices 1A, 1B and 1C exchanges necessary data, and outputs the communication data to the subsequent communication device. In the above description, the connection unit has been described as using an electrical contact element as an example in the case of using an electric signal in a communication path. It can be easily realized by combination or direct switching of the optical waveguide by an optical selector.

FIG. 2 shows an operation example of a communication path switching apparatus for connecting three slave communication apparatuses 1A, 1B and 1C to the master communication apparatus 2 of the present invention by using an electrically looped communication path. FIG. 3 is a block diagram illustrating the operation of the communication path switching device when a disconnection (indicated by X) occurs, with reference to FIG. First, when a disconnection occurs in the communication path 5C (failure occurrence point a), the communication processing unit 11 of the slave communication device 1C
Since the input signal to C is cut off, the communication processing unit 11C detects the disconnection and transmits a disconnection detection to the master communication device 2. Here, the switching control unit 12 of the master communication device 2 and the switching control units 12A, 1A of the slave communication devices 1A, 1B, and 1C.
2B and 12C close the connection units 10, 10A, 10B, and 10C by confirming that there is no signal on the communication path from the preceding stage, and at the same time, drivers 31, 31A, and 31C respectively.
B, output of 31C is stopped. Thereafter, the main control unit 21 of the master communication device 2 outputs communication data to the slave communication device 1A, and the communication processing unit 11A of the slave communication device 1A receives the communication data and
Outputs response data to Upon receiving the response data from the slave communication device 1A, the main control unit 21 of the master communication device 2 outputs communication data to the slave communication device 1B, and the communication processing unit 11B of the slave communication device 1B receives the communication data. Then, response data is output to master communication device 2. When receiving the response data from the slave communication device 1B, the main control unit 21 of the master communication device 2 outputs the communication data to the slave communication device 1C, but the communication path 5C of the slave communication device 1C is disconnected. The communication data cannot be received, and no response data is output. Connection cables 4A, 4
An example of each data of B, 4C, and 4D is shown in Data 1 at the time of abnormality in FIG. In response to the communication data output from the master communication device 2 to each of the slave communication devices 1A to 1C, the slave communication devices 1A and 1B receive the respective communication data and output response data. 1C indicates that no response data is output.
By the above operation, the main control unit 21 of the master communication device 2
Are connection cables and communication paths 4A, 5A, 6A, 4B,
With the paths 5B, 6B, 4C, 6C, and 4D, good connection can be confirmed, and the path of the communication path 5C where a disconnection may have occurred can be limited. Recovery can be facilitated.

Next, when a disconnection occurs in the connection cable 4C (failure occurrence point b), an input signal to the communication processing unit 11C of the slave communication device 1C is cut off, and the communication processing unit 11C detects the disconnection. Then, the disconnection detection is transmitted to the master communication device 2. Here, the switching control unit 12 of the master communication device 2 and the switching control units 12A, 12B, and 12C of the slave communication devices 1A, 1B, and 1C confirm that there is no signal on the communication path from the preceding stage. As soon as 10C is closed, the drivers 31 and 31 are closed.
The output of A, 31B and 31C is stopped. Thereafter, the main control unit 21 of the master communication device 2 outputs communication data to the slave communication device 1A, and the communication processing unit 11A of the slave communication device 1A receives the communication data and outputs response data to the master communication device 2. . When receiving the response data from the slave communication device 1A, the main control unit 21 of the master communication device 2 outputs communication data to the slave communication device 1B, and then outputs the communication data to the slave communication device 1B.
1B receives the communication data and outputs response data to the master communication device 2. Main control unit 2 of master communication device 2
1 receives the response data from the slave communication device 1B, and then outputs communication data to the slave communication device 1C. The communication processing unit 11C of the slave communication device 1C receives the communication data and sends it to the master communication device 2. Output response data. At this time, the connection cables 4A, 4B, 4
An example of each data of D is shown in Data 2 at the time of abnormality in FIG. This means that, in response to communication data output from the master communication device 2 to each of the slave communication devices 1A to 1C, the slave communication devices 1A, 1B, and 1C receive respective communication data and output response data. Is shown. By the above operation, the main control unit 21 of the master communication device 2
Connection cables and communication paths 4A, 5A, 6A, 4B, 5
In the paths B, 6B, 5C, 6C, and 4D, good connection can be confirmed, and the path of the connection cable 4C in which the disconnection may have occurred can be limited. Recovery can be facilitated.

Next, when a disconnection occurs in the communication path 6B (fault occurrence point c), an input signal to the communication processing unit 11C of the slave communication device 1C is cut off.
1C detects the disconnection and transmits a disconnection detection to the master communication device 2. Here, the switching control unit 1 of the master communication device 2
2. Switching control unit 1 of slave communication devices 1A, 1B, 1C
2A, 12B, and 12C close the connection units 10, 10A, 10B, and 10C by confirming that there is no signal on the communication path from the previous stage, and at the same time, drivers 31, 31A,
The output of 31B and 31C is stopped. Thereafter, the main control unit 21 of the master communication device 2 outputs communication data to the slave communication device 1A, and the communication processing unit 11A of the slave communication device 1A receives the communication data and outputs response data to the master communication device 2. I do. When receiving the response data from the slave communication device 1A, the main control unit 21 of the master communication device 2 outputs the communication data to the slave communication device 1B, but the communication path 6B of the slave communication device 1B.
Cannot receive the communication data because it is disconnected, and does not output response data. Next, the main control unit 21 of the master communication device 2 outputs communication data to the slave communication device 1C, and the communication processing unit 1 of the slave communication device 1C.
1C receives the communication data and outputs response data to the master communication device. Connection cables 4A, 4
An example of each data of B, 4C, and 4D is shown in Data 3 at the time of abnormality in FIG. In response to the communication data output from the master communication device 2 to each of the slave communication devices 1A to 1C, the slave communication devices 1A and 1C receive the respective communication data and output response data. 1B indicates that no response data is output.
By the above operation, the main control unit 21 of the master communication device 2
Are connection cables and communication paths 4A, 5A, 6A, 4B,
With the paths 5B, 4C, 5C, 6C, and 4D, good connection can be confirmed, and the path of the communication path 6B where the disconnection may have occurred can be limited. Recovery can be facilitated.

Further, even if the control of each slave communication device is stopped when each of the slave communication devices 1A to 1C confirms that there is no signal on the communication path from the preceding stage, the connection of the communication path can be confirmed by the above operation. The slave communication device can transmit and receive communication data. For this reason, if a series of interrupted processes are completed or the slave communication device is performing actuator operation processing, even if the control target of the normal slave communication device stops at a dangerous place, the fault that has occurred is recovered. It can be evacuated to a safe place before it is made to work.

In the above description, the master communication device 2 and the slave communication devices 1A, 1A
A description has been given of the case where the connection units 10, 10A, 10B, and 10C of B and 1C are switched, but the connection units 10, 10A, and 10C are switched in response to a command from the main control unit 21 of the master communication device 2.
By closing B and 10C and determining the presence or absence of a response signal from each slave communication device to the communication data output by the main control unit 21, it is also possible to specify the location where a failure has occurred in the communication path.

[0015]

As described above, according to the communication path switching device for connecting a plurality of slave communication devices to the master communication device of the present invention by using an electrically looped communication path, the master communication device and each By providing a connection unit that connects the output of the driver of the slave communication device to the input of the receiver, and a switching control unit that controls the connection switching of the connection unit and the communication output of the driver, the connection of the communication path when disconnection occurs Can be identified to identify the location where the disconnection has occurred, thereby facilitating recovery in the event of a failure. In addition, since communication data can be transmitted and received with respect to a normal slave, if a series of interrupted processes is completed, or if the slave communication device is performing actuator operation processing, the control target of the normal slave communication device Even if the vehicle stops at a dangerous place, it can be evacuated to a safe place before the trouble that has occurred is restored.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a communication path switching device of the present invention.

FIG. 2 is a block diagram showing an embodiment for explaining an operation of the communication path switching device according to the present invention at the time of disconnection.

FIG. 3 is a diagram showing an example of data of each connection cable when the communication path switching device of the present invention is disconnected.

FIG. 4 is a block diagram showing an embodiment of a conventional communication device.

FIG. 5 is a diagram illustrating an example of data of each connection cable when the conventional communication device is normal.

[Explanation of symbols]

1A, 1B, 1C Slave communication device 10, 10A, 10B, 10C Connection unit 11A, 11B, 11C Communication processing unit 12A, 12B, 12C Switching control unit 2 Master communication device 21 Main control unit 31, 31A, 31B, 31C Driver 32 , 32A, 32B, 32C Receiver 4A, 4B, 4C, 4D Connection cable 5A, 5B, 5C Communication path (slave communication apparatus input side) 6A, 6B, 6C Communication path (slave communication apparatus output side) A1, B1, C1 Data (Communication data to slave communication device) a1, b1, c1 data (response data of slave communication device)

Claims (4)

[Claims] A master communication device including a driver and a receiver, and a plurality of slave communication devices are connected to a receiver of another communication device with the driver, and the master communication device electrically connects the plurality of slave communication devices. In a communication device connected using a loop-like communication path, a connection unit that connects the output of the driver to the input of the receiver,
A communication path switching device, comprising: a switching control unit that controls connection switching of the connection unit and communication output of the driver. 2. The communication path switching device according to claim 1, wherein the switching control section switches the connection section depending on the presence or absence of an output signal from a preceding stage, and controls the communication output of the driver. 3. The communication path switching device according to claim 1, wherein the switching control unit switches the connection unit in response to a command from the master communication device, and controls a communication output of the driver. 4. The connection section of the slave communication device is always closed before power is turned on. When the power is turned on, the switching control section of the slave communication device performs self-diagnosis and performs normal communication. 4. The communication path switching device according to claim 1, wherein the connection unit of the slave communication device is switched only when it is determined that the connection can be performed.