JP2010062861A - Ring type network system and method for restoring same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a processing load of a master station when the line is restored from a disconnection state at a state that a connection state of a line is maintained by performing loop back by generation of disconnection. <P>SOLUTION: When restoration of the disconnection state is notified from a loop back station which performs the loop back, a transmission command frame for instructing execution of preprocessing for transiting a separated station which is separated by the loop back to a state such as an initial state before restoration which should be in restoration to a line is transmitted from a master station to a loop back station, in the loop back station, the transmission command frame is transmitted to the separated station, and the specified preprocessing is executed in the separated station. In the master station, after receiving a response from the separated station to the transmission command frame, a loop back release instruction is performed to the loop back station to release the loop back, and processing in line restoration in accordance with reconnection of the separated station to the line is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, a ring network is constructed by a master station and a plurality of slave stations, and in this ring network, a data exchange process is performed by circulating a transmission frame on a line to which each station is connected. The present invention relates to a recovery method for a ring network system and a ring network system.

  Conventionally, in a ring network system, for example, if a disconnection state occurs due to a line failure or station failure such as disconnection or connector disconnection, the station near this disconnection location must be disconnected. Is detected and looped back, and the line is maintained in the connected state by this loopback, so that data exchange is continued between the stations excluding the stations disconnected by the loopback (for example, patents) References 1 and 2).

In addition, when a station that has detected a disconnection or a device that is a line component detects a recovery from the disconnection state of the disconnection point, the loopback is automatically canceled, including the station disconnected by the loopback, Data exchange between stations connected to one line is resumed (see, for example, Patent Document 3).
JP-A-2-294136 JP-A-3-206752 JP-A-5-276182

  For example, as shown in FIG. 8, a master station and a plurality of slave stations are connected by a bus, and a ring network is constructed by looping back a line at stations located at both ends, and a slave station SL1, a master station M0, and a slave In the ring network system in which the bus connection is made in the order of the station SL2, the slave station SL3, and the slave station SL4, as shown in FIG. 8, it is assumed that there is a disconnection state between the slave station SL2 and the slave station SL3. The slave station SL2 performs loop back.

  For this reason, it is divided into group A consisting of slave station SL1, master station M0, and slave station SL2 connected to the same line, and group B consisting of slave station SL3 and slave station SL4 separated from the line of group A. Thus, in group A connected to the same line as master station M0, each slave station continues to communicate with master station M0. However, in group B disconnected from master station M0, each slave station is connected to master station M0. Communication is not possible.

  Accordingly, data refresh is not performed in each slave station of group B. Since the data refresh data from the master station M0 cannot be received, each slave station in the group B determines that some abnormality has occurred in the master station M0, stops its own operation, and maintains the state as it is. Alternatively, an operation such as stopping the operation of the own station and returning to the initial state is performed. That is, when viewed as the entire ring network system, the group A including the master station M0 is in a normal state, while each slave station in the group B is in a state equivalent to being in a failure state.

  As described above, when each station of group B is in a failure state, the disconnection state is recovered and the connection state is recovered. When the recovery of the disconnection is detected by the slave station SL2 and the loopback is canceled, the master station M0 If it sees, the slave station (slave station SL3, slave station SL4) group which existed previously and dropped out for some reason has returned to the line in the fault state, that is, returned to the management of the master station M0. .

  Therefore, in the master station M0, as each slave station in group B recovers, line recovery processing such as addition of data processing or addition of delay time associated with the return of these slave stations to the line, When returning each slave station of a certain group B to the line and returning to the management of the master station M0, it is necessary to perform preprocessing for shifting the state of each slave station to a predetermined state (pre-return state). There is.

For example, in the case of a network system in which robot control is performed in the entire network system and each slave station controls each part of the robot, it is necessary to perform operations in cooperation between the slave stations. . For this reason, the part controlled by the slave station of group B, for example, the arm or the like is returned to the preset initial position, or the position information of the part controlled by the other slave station used by the slave station of group B Before starting control of the entire system including group B slave stations, such as updating parameters, the status of each slave station is shifted to the specified pre-return state set for each slave station. It is necessary to perform pre-processing for making it happen.
Since it is necessary to perform such preprocessing and line restoration processing, processing at the master station at the time of disconnection restoration becomes complicated. Further, as the number of slave stations to be restored increases, the amount of preprocessing to be performed by the master station also increases.

In general, recovery processing from failure and re-initialization processing often include time waiting processing (for example, initialization completion waiting), etc., and waiting in parallel while partially operating the machine (system) It is often difficult to execute a process including a temporal element such as (or takes a long processing time). This results in disturbance of the machine control cycle.
The master / slave control during operation is optimized to be simple and immediately responded, but initialization and the like often involve complicated exchanges during non-operational processing.
Furthermore, since individual control is performed for each slave station, the processing content of the preprocessing differs depending on the function and setting of each slave station.

  For example, if the slave station is an output module of a control device, once the data update from the master station is interrupted, there are cases where all the output values are reset and when the previous output values are continuously output. is there. These differ depending on the specifications of the equipment realized using this output module. In such a case, it is difficult to reset all the slave stations that have been recovered collectively, or to return the data as it is without resetting the output data. For this reason, it is necessary to reset or restore the state as it is in accordance with the state to be restored for each slave station, which also leads to an increase in processing at the time of restoration of disconnection in the master station.

In this way, if there is a lot of processing at the time of restoration of disconnection at the master station, it will take time to complete all the processing, that is, from the slave station that has returned to the line, it will be connected to the line Although it is possible to communicate with the master station, it takes time for the slave station to start drive control in response to an instruction from the master station. Even though the operation is possible, the function as a slave station cannot be executed.
Therefore, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and it is possible to simplify the processing of the master station at the time of recovery from the disconnection state and reduce the processing load. The present invention relates to a ring network system and a recovery method of the ring network system.

  In order to achieve the above object, an invention according to claim 1 of the present invention provides a ring between one master station and a plurality of slave stations connected to the master station via a line and managed by the master station. Type network is established, and when any of the stations detects a disconnection state in which communication with an adjacent station is disabled, a loopback is performed to establish a connection state with the master station via the line. By continuing communication between certain stations and releasing the loopback when the restoration of the disconnection state is detected, the slave station disconnected from the master station by the loopback is transferred to the master via the line. In a ring network system that is reconnected to a station, the master station detects the recovery of the disconnection state by the loopback when the recovery of the disconnection state is detected. A command for preprocessing is generated for the disconnected station that has been disconnected from the former, and a command for transition to the pre-return state set in advance as a state when the disconnected station is reconnected to the master station is generated. A preprocessing command frame transmitting means for transmitting to the loopback station performing the loopback as a processing command frame; and after the response command frame is notified as a response to the preprocessing command frame, the loopback station And a circuit recovery processing means for executing processing at the time of a predetermined circuit recovery, and when the loopback station receives the preprocessing command frame, Preprocessing command frame relay means for transmitting a preprocessing command frame to the disconnection station; and Response relay means for transmitting a response command frame received from the disconnecting station as a response to the processing command frame to the master station, and the disconnecting station receives the preprocessing command frame when the preprocessing command frame is received. A predetermined pre-process is executed according to the processing command frame and the response command frame is transmitted.

The invention according to claim 2 is that the pre-return state is set for each slave station in accordance with the function of the slave station, and the master station detects the loopback when the disconnection state is detected. A disconnection station specifying means for specifying the disconnection station to be reconnected to the master station by releasing the command, and the preprocessing command transmitting means for each disconnection station specified by the disconnection station specifying means Generating a command for preprocessing according to the pre-return state set in a station, and transmitting the command as the preprocessing command frame in association with the disconnected station specified by the disconnected station specifying means. It is a feature.
The invention according to claim 3 is characterized in that the ring-type network is configured by connecting the master station and the slave station by a bus and turning back a line at stations located at both ends.

  According to a fourth aspect of the present invention, a ring network is constructed by one master station and a plurality of slave stations connected to the master station via a line and managed by the master station. By performing a loopback when the station detects a disconnection state in which communication with an adjacent station is disabled, communication is continued between the stations connected to the master station via the line. When the recovery of the disconnection state is detected, the loopback is canceled, so that the slave station disconnected from the master station by the loopback is reconnected to the master station via the line. In the recovery method of the ring network system, when recovery from the disconnection state is detected, the master station is disconnected from the master station by the loopback. For the disconnected station, a preprocessing command is generated for shifting to the pre-return state set in advance as a state when the disconnected station is reconnected to the master station, and the command is transmitted to the preprocessing command frame. A step of transmitting to the disconnecting station via the loopback station performing the loopback, and the disconnecting station that has received the preprocessing command frame has a predetermined value in accordance with the preprocessing command frame. Executing pre-processing and transmitting a response command frame to the pre-processing command frame; and after the master station receives the response command frame via the loop-back station, A step of instructing cancellation of the loopback and executing processing at the time of a predetermined line restoration It is characterized in that it comprises.

  According to the ring network system of the present invention, when a disconnection state is restored in a state in which any station maintains a connection state by looping back when a disconnection state occurs, the master station Before a transition to a pre-return state set in advance as a state when the disconnected station is connected to the master station with respect to the disconnected station disconnected by the loopback to the loopback station performing the loopback The processing command frame is transmitted, the loopback station transmits the preprocessing command frame to the disconnecting station, and the disconnecting station performs predetermined preprocessing according to the preprocessing command frame and transmits a response command frame.

Then, after receiving the response command frame from the disconnecting station via the loopback station, the master station instructs the loopback station to cancel the loopback, and then executes the process for line restoration.
For this reason, when the disconnection station becomes ready for communication with the master station as the loopback is released, the pre-processing for the disconnection station has been completed, and therefore only the process at the time of line restoration may be performed. Therefore, the master station does not need to perform pre-processing for the disconnected station and processing for line restoration at the same time, so that the processing load on the master station can be reduced accordingly.
In addition, preprocessing including time-consuming processing, such as waiting processing that does not fit in the control cycle, is completed when the disconnected station is reconnected, so that the effect of disturbing the control cycle due to reconnection is reduced. it can.

Embodiments of the present invention will be described below.
FIG. 1 shows an example of a ring network system to which the present invention is applied. A master station M0 and a plurality of slave stations SL1 to SL4 are connected by a bus. These stations are bus-connected in order of slave station SL1, master station M0, slave station SL3, and slave station SL4, and form a ring network by looping back the lines at slave stations SL1 and SL4 located at both ends. Yes. Then, data is exchanged between the stations by circulating the transmission frame on the line.

The master station M0 manages the slave stations SL1 to SL4. For example, the master station M0 controls driving of the slave stations SL1 to SL4, and each slave station controls driving of the controlled object. Predetermined drive control is performed, and the entire system performs predetermined drive control such as robot control.
Further, the master station M0 determines whether each slave station is connected to the line to which the master station M0 is connected or is disconnected based on the communication status with each slave station. In addition to managing the state, it manages the arrangement position status of each station.

  Further, when the master station M0 receives a disconnection state detection and a loopback notification from the slave station, the master station M0 determines the station disconnected from the line by the loopback from the station number of the station that made the loopback notification and the station arrangement status. recognize. On the other hand, when disconnection recovery is notified from the slave station that issued the loopback notification, the station recognized as a station disconnected from the line at the time of loopback is instructed to execute pre-processing upon returning to the line. A transparent command frame is generated and transmitted to the station that has notified the disconnection recovery. Here, the return to the line means that the slave station dropped from the line is reconnected to the master station M0 via the line and communication with the master station M0 becomes possible.

FIG. 2 is an example of a format of a frame exchanged between stations.
The frame is composed of, for example, a frame identifier indicating whether the frame is a normal command frame or a transparent command frame, a frame destination station number, a frame transmission source station number, a command type, a data size, command data, and a frame check code. The
On the other hand, each of the slave stations SL1 to SL4 receives the frame transmitted from the master station M0, reads the command data addressed to itself when it is designated as the destination station number, and transmits it to the next station. If the local station is not specified as, it transmits to the next station as it is. If the received frame identifier is a normal command frame, a process specified by command data addressed to the own station is performed.

Further, when the local station is in a loopback state, the frame identifier of the frame addressed to the local station is a transparent command frame, and the transmission source is the master station M0, the command data header in the received transparent command frame is displayed. A transparent command frame addressed to the disconnecting station is generated with the station number of the described disconnecting station as a new destination station number.
Then, this transparent command frame is transmitted to a designated slave station, that is, a disconnection station. When a transparent command frame that circulates around the disconnection station is received, the transparent command frame addressed to the own station received from the master station is returned to the master station M0.

  The slave stations SL1 to SL4 monitor the communication status with the adjacent slave stations, and loop back when communication with the adjacent slave stations cannot be performed due to disconnection or failure. To move to the loopback station and notify the master station M0 that a disconnection state has been detected. Further, when communication with an adjacent slave station is resumed in a disconnected state, it is determined that the disconnected state has been recovered, and the master station M0 is notified of the recovery of the disconnected state.

Any method may be used to detect the disconnection state. For example, a preset frame transmission / reception time-out time and the number of retries are set, and a disconnection occurs when there is no transmission / reception exceeding this time / number of times. . Alternatively, a signal for confirming the inter-station response is periodically transmitted and received.
In addition, when the slave stations SL1 to SL4 have not received a frame from the master station M0 for a predetermined time, the slave stations SL1 to SL4 determine that an abnormality has occurred in the master station M0 and execute processing when the master station M0 is abnormal. . For example, the current state is maintained as it is, or the state shifts to a predetermined state that should be taken when the master station M0 is abnormal.
When the slave stations SL1 to SL4 are disconnected from the line and receive a transparent command frame addressed to themselves from other slave stations, the slave stations SL1 to SL4 execute preprocessing specified by the command data of the frame. The received transparent command frame is transmitted to the next station.

Next, the operation of the present invention will be described with reference to the flowcharts of FIGS.
FIG. 3 is a flowchart illustrating an example of a processing procedure of the master station M0 that is executed when a disconnection state is detected. FIG. 4 is a flowchart illustrating an example of a processing procedure in the slave station performing loopback when the disconnection state is recovered. FIG. 5 is a flowchart illustrating an example of a processing procedure in the slave station disconnected from the line by loopback when the disconnected state is recovered.

  For example, when a line disconnection occurs between the slave station SL2 and the slave station SL3 as shown in FIG. 8, the slave station SL2 receives, for example, a frame to be transmitted from the adjacent slave station SL3 at a predetermined period. If it is determined that a disconnection has occurred between the slave station SL2 and the slave station SL3, for example, the slave station SL3 and the slave station SL4 are disconnected from the line by looping back, and the slave station SL1, the master station M0, and the slave station SL2 To continue communication between the two.

In addition, the slave station SL2 notifies the master station M0 that a disconnection state has occurred and that the local station is in a loopback state. As a result, the slave station SL2 becomes a loopback station.
When the disconnection state is notified, the master station M0 starts processing at the time of disconnection state detection in FIG. 3, and first recognizes the station disconnected by loopback at the slave station that detected the disconnection state. Specifically, a station that has been disconnected is recognized from the station number of the slave station that has detected the disconnection state and the arrangement position of each station that is held in advance, and this is stored as a disconnected station in a predetermined storage area. (Step S1).

  The slave station SL2, which is a loopback station, monitors whether or not the disconnection state with the slave station SL3 has been recovered, and for example, receives a frame that is to be transmitted from the slave station SL3 at a predetermined period. When it becomes, it recognizes that the disconnection state between slave station SL2 and slave station SL3 was recovered. When the recovery of the disconnection state is detected in this way, the slave station SL2 first notifies the master station M0 of the recovery of the disconnection state in step S21 as shown in the flowchart of FIG.

When the master station M0 receives the recovery notification, the master station M0 shifts from step S2 to step S3 in FIG. 3 to create and transmit a transparent command frame.
Specifically, when a disconnection state is notified, a transparent command frame for instructing execution of pre-processing to the disconnected station stored in a predetermined storage area in step S1 is created. The processing contents of the preprocessing corresponding to each disconnection station are set in advance and stored in a predetermined storage area. As the preprocessing, as described above, each slave station is restored to a predetermined state, such as the controlled device of each slave station is shifted to the initial state, or various parameters used in each slave station are updated to the current values. There are processes for shifting to the previous state.

Here, for example, as a pre-process associated with the return to the line, if a transition to the initial state, which is the state at the time of system startup, is instructed, a transparent command frame for instructing a reset to the initial state is created. . That is, in the frame format shown in FIG. 2, a transparent command frame is set as a frame identifier, the station number of the slave station performing the loopback that notifies disconnection restoration as the destination station number, the source station number is the master station M0, and the command type is Pre-processing command to instruct execution of pre-processing, command data size is set as data size, and instruction to shift to the initial state for slave station SL3 and slave station SL4 which are disconnected stations is set as command data To do.
Then, the transparent command frame is transmitted to the slave station SL2 that is looping back.

  When the slave station SL2 which is a loopback station receives a transparent command frame addressed to itself, the slave station SL2 shifts from step S22 to step S23 in FIG. 4 to read the frame data, and to read the slave station SL3 and the slave designated by the frame data. A transparent command frame for instructing the transition to the initial state addressed to the station SL4 is generated. Since the slave station SL2 is looped back, the transmission frame is not normally transmitted to the slave stations SL3 and SL4. However, when the command identifier is a transparent command frame, the transparent command frame is transmitted to the slave station SL3 and the slave station SL3. Transmit to the slave station SL4. That is, the slave station SL3 and the slave station SL4 are designated as the destination station numbers, and a command for instructing reset to the initial state is set.

  When receiving the transparent command frame addressed to the local station, the slave station SL3 and the slave station SL4, which are the disconnecting stations, move from step S41 to step S42 in FIG. 5 and execute the process specified by the transparent command frame. In this case, since the reset instruction to the initial state is given, the state of the own station is reset to the initial state. And the process when it recovers from a disconnection state is complete | finished.

  On the other hand, in the slave station SL2 that has detected the disconnection recovery, the process proceeds from step S23 in FIG. 4 to step S24 to determine whether or not a transparent command frame has been received from the disconnecting station. If a transparent command frame has not been received from the disconnecting station for a predetermined time, the process proceeds from step S24 to step S30, and the disconnecting station is determined to be abnormal. For example, the master station M0 is notified that the disconnecting station is abnormal. To transmit a transparent command frame. And the process at the time of disconnection restoration is complete | finished.

On the other hand, if the slave station SL2 receives a transparent command frame from the disconnecting station, the process proceeds from step S24 in FIG. 4 to step S25, and returns the transparent command frame received to the own station to the master station M0. Further, it recognizes that the slave stations SL3 and SL4 which are the disconnecting stations are normal.
When the master station M0 receives the transparent command frame (step S4), the transparent command frame transmitted in step S3 circulates around the slave station SL3 and the slave station SL4 that are the cut-off stations and returns to the slave station. Judge that it is normal. And the measurement of the elapsed time from this time is started.

When the elapsed time from the reception of the transparent command frame reaches a predetermined time, that is, when a sufficient time has elapsed for the reset processing in the slave station SL3 and the slave station SL4 to end, a loopback release instruction Is transmitted to the slave station SL2 that detects the disconnection recovery (step S5).
As a result, in the slave station SL2 that detects the disconnection restoration, the process proceeds from step S26 in FIG. 4 to step S27 to cancel the loopback. Then, the master station M0 is notified that the loopback has been released, and the process at the time of disconnection recovery is terminated.

  In the master station M0, when the loopback cancellation notification is made from the slave station SL2 that detects the disconnection recovery, the process proceeds from step S6 to step S7 in FIG. That is, for example, when the slave station SL3 and the slave station SL4 that have returned to the line transmit frames to the master station M0 and receive frames from the slave station SL3 and slave station SL4, the slave station once disconnected from the line Recognizing that SL3 and slave station SL4 have returned to the connected state again, starting data processing for slave station SL3 and slave station SL4, and adjusting the transmission timing associated with the reconnection of these stations to master station M0 A preset line restoration process such as. Then, when the predetermined line restoration process is completed, the process at the time of detecting the disconnection state is terminated, and thereafter, the process shifts to the steady state, and the slave stations SL1 to SL4 are driven and controlled.

  FIG. 6 shows the flow of frames transmitted and received between the master station M0 and the slave stations SL2 to SL4 from when the disconnection state is detected to when the ring network system of FIG. 1 recovers. . In FIG. 6, a normal command frame is described as a normal frame, and a transparent command frame is described as a transparent command. FIG. 7 shows the data flow in the network system. In FIG. 6, illustration of the slave station SL1 located upstream of the master station M0 is omitted for the explanation of the frame flow.

As shown in FIG. 1, when no disconnection abnormality has occurred, the normal command frame transmitted from the master station M0 at the time t1 is transmitted to the master station M0, the slave station SL2, the slave station SL3, and the slave station SL4. The slave station SL3 and the slave station SL2 are returned to the master station M0. The master station M0 transmits this to the slave station SL1, and the slave station SL1 returns it to the master station M0. As a result, the transmission frame goes around each station via the line.
In each station, when the received frame is a frame addressed to itself, this is read and a predetermined process is executed. As a result, data can be exchanged between the stations constituting the network system.

If disconnection occurs between the slave station SL2 and the slave station SL3 from this state as shown in FIG. 8, the slave station SL2 detects the disconnection state and shifts to a loopback state.
For this reason, when the slave station SL2 receives the normal command frame at the time t2, a disconnection occurs between the slave station SL2 and the slave station SL3, so that the slave station SL3 does not transmit to the slave station SL3. Loop back at SL2 and return to master station M0. Therefore, although the slave station SL3 and the slave station SL4 cannot exchange data with the master station M0, the slave station SL1 and the slave station SL2 are connected to the master station M0 via a ring-shaped line. Therefore, data exchange with the master station M0 can be continued.

In addition, when returning the normal command frame addressed to the own station to the master station M0, the slave station SL2 adds, as the status of the own station, that a disconnection abnormality has been detected and that the own station has entered a loopback state. Transmit to station M0.
The master station M0 recognizes the disconnection abnormality notice from the slave station SL2 and the station disconnected by the loopback of the slave station SL2 (step S1 in FIG. 3).

  When the disconnection state is recovered from this state and the slave station SL2 detects this, the slave station SL2 notifies the master station M0 of the recovery of the disconnection state. For example, when returning the normal command frame addressed to the own station from the master station M0 transmitted at the time t3, it is transmitted with the fact that the disconnection state has been restored and the loopback is being performed as the status of the own station ( FIG. 4 step S21). Note that when the recovery from the disconnection state is detected, the slave station SL2, which is a loopback station, does not cancel the loopback.

  In the master station M0, when recovery from the disconnection abnormality is notified from the slave station SL2, the disconnected stations are the slave station SL3 and the slave station SL4, so that the slave station SL3 and the slave station SL4 are brought back to the line. As pre-processing, for example, a transparent command frame instructing reset to the initial state is generated and transmitted to the slave station SL2 (time t4, steps S2 and S3 in FIG. 3).

When the slave station SL2 receives the transparent command frame addressed to itself, the slave station SL3 and the slave station SL4 are instructed to reset the slave station SL3 and slave station SL4. A transparent command frame is generated and transmitted to the slave stations SL3 and SL4 (steps S22 and S23 in FIG. 4).
When the slave station SL3 and the slave station SL4 receive the transparent command frame addressed to the own station, the slave station SL3 captures the contents and transmits the transparent command frame to the next station. And since the reset instruction | indication is made, the transfer process to an initial state is started (FIG. 5 step S41, S42).

On the other hand, when the slave station SL2 receives the transparent command frame that circulates the slave stations SL3 and SL4, it returns the transparent command frame addressed to itself to the master station M0 (steps S24 and S25 in FIG. 4).
When the master station M0 receives the transparent command frame at the time t5, the master station M0 determines that the transparent command frame transmitted at the time t4 has reached the slave station SL3 and the slave station SL4 that are separated by the loopback. The measurement of the elapsed time from the time of reception is started.

  Until the predetermined time elapses, no instruction is issued to cancel the loopback, and data is exchanged between the master station M0, the slave station SL1, and the slave station SL2 by frame wrapping while maintaining the loopback. Perform (time t6). In addition, when the slave station SL2 receives a normal command frame addressed to itself from the master station M0, the slave station SL2 adds to the normal command frame that the disconnection state has been restored as the status of the own station and that it is in a loopback state. To return to the master station M0.

  Then, in the master station M0, it is predicted that the reset process in the slave station SL3 and the slave station SL4 is completed when the elapsed time from the time when the arrival of the transparent command frame is confirmed reaches a predetermined time set in advance. At time t7, the normal command frame of the loopback release command is transmitted to the slave station SL2 (steps S4 and S5 in FIG. 3).

The slave station SL2 reads the frame data of the loopback release command and returns it to the master station M0. Since the loopback cancellation is instructed, the loopback cancellation is performed (steps S26 and S27 in FIG. 4).
Therefore, when the normal command data is transmitted next at time t8, the normal command frame is transmitted to the slave station SL2, the slave station SL3, and the slave station SL4, and passes through the slave station SL3 and the slave station SL2 to become the master station M0. Returned to For this reason, data exchange between the slave stations SL1 to SL4 and the master station M0 is resumed.

Here, when the slave station SL2 cancels the loopback, the reset processing in the slave station SL3 and the slave station SL4 has already been completed. That is, the slave stations SL3 and SL4 are in an initial state, and these are the states set as the state of the slave station before returning.
Therefore, the master station M0 does not need to control the slave station SL3 and the slave station SL4 to the initial state when the loopback is canceled, and the slave station SL3 and the slave station SL4 are again connected to the line. It is only necessary to perform the line restoration process associated with this.

  Therefore, since it is not necessary for the master station M0 to perform the pre-processing and the line restoration process at the same time when the loopback is released, it is possible to reduce the load on the master station M0 when the loopback is released. For this reason, it is possible to shorten the time required from the time when the loopback is released to the start of system control including the slave station SL3 and the slave station SL4. For this reason, it is possible to shorten the recovery time at the time of disconnection recovery, and in the case of a network system using a programmable controller or a network system constituting a machine control system, it is possible to improve reliability and productivity. .

In addition, since the preprocessing and the line restoration processing can be clearly separated as the processing at the master station M0, the processing structure at the master station M0 can be simplified.
Also, the failure information of the slave station that has returned to the line returns to the line in a cleared state. Therefore, for example, even if the master station M0 is configured to collect and store the failure information of the slave station as maintenance information for maintenance of the network system, the master station M0 Since the station recognizes it as a normal state, slave station failure information is not collected. Therefore, in the event of a temporary disconnection, such as when communication cannot be temporarily performed due to something, avoiding the collection of failure information associated with this temporary disconnection as maintenance information can do. For this reason, it is possible to avoid collecting relatively minor failure information such as a temporary disconnection state as maintenance information.

In the above embodiment, the case where both the slave station SL3 and the slave station SL4 are reset to the initial state as the state before returning to the line has been described, but the present invention is not limited to this.
As described above, the state that each slave station should return to the line depends on the controlled device of each slave station, that is, the state before return differs. Different.

  For example, the slave station SL3 shifts to a pre-return state (for example, an initial state) set in advance as a state that should be present when the line is restored as pre-processing, and the slave station SL4 performs pre-processing with other slave stations. When setting the current values of other slave stations as various parameters for matching, the master station M0 sets a reset command that instructs the slave station SL3 to shift to the state before return, For SL4, an update command for instructing update of various parameters and update data are set. Then, these are transmitted as a transparent command frame to the slave station SL2.

In the slave station SL2, a transparent command frame including a reset command addressed to the slave station SL3, an update command addressed to the slave station SL4, and update data is transmitted to the slave station SL3 and the slave station SL4.
The slave station SL3 that has received this transparent command frame reads the reset command addressed to itself and performs a reset process to a predetermined state before return, and the slave station SL4 reads the update command and update data addressed to itself and is designated. The parameter values of various parameters are updated to update data.
In this way, the present invention can be applied even when the processing contents of the preprocessing for the slave station SL3 and the slave station SL4 are different.
In the above-described embodiment, the slave station SL3 and the slave station SL4 have described the case where only the reset process is performed according to the reset instruction in the transparent command frame. However, the present invention is not limited to this.

  For example, in a transparent command frame, a response request and a transmission request for predetermined information are added to the slave stations SL3 and SL4, and the response request and the transmission request are added to the slave stations SL3 and SL4. If so, the designated information is added to the transparent command frame and transmitted to the next station, or a response frame is newly created and transmitted to the slave station SL2 which is the loopback station. The transparent command frame and the response frame to which the predetermined information from the slave station SL3 and the slave station SL4 is added may be transmitted from the slave station SL2 to the master station M0 at a predetermined timing. .

  As described above, by transmitting the information required by the master station M0 from the slave station SL3 or the slave station SL4, the master station M0 side needs necessary information such as the status at the slave station SL3 or the slave station SL4. Various processes can be executed after collecting the information. For this reason, for example, when the preprocessing is completed from the slave station SL3 or the slave station SL4 side, the master station M0 notifies the end of the preprocessing in the slave station SL3 or the slave station SL4. You can wait and release the loopback.

In the above embodiment, a case has been described in which only a transparent command frame for instructing a resetting station is transmitted from the master station M0. However, the present invention is not limited to this.
For example, when the instruction station and the response data are exchanged between the master station and the disconnection station, the response command from the disconnection station is used when the disconnection station is shifted to the pre-return state by following multiple steps. Then, the transparent command frame may be transmitted again from the master station.

By doing in this way, for example, after resetting the disconnected station in the fault state once to the initial state, the initial value is set again, and after confirming that the initial value is correctly read and reflected, Even when returning to the line, it is possible to accurately shift to the state before return.
In addition, when a sequence is required for each slave station to shift to a predetermined pre-return state, the master station generates a transparent command frame addressed to each slave station and transmits it to each slave station first. It is only necessary to wait for a response command to the transparent command frame and transmit the next transparent command frame.

  Also, in a mechanical system composed of a plurality of slave stations, when a slave station is initialized and returned to the original position, then other stations are initialized, etc. When a sequence is required, the master station first transmits a transparent command frame instructing predetermined preprocessing for the first slave station, waits for a response, and transmits a predetermined previous value for the second slave station. Transmits a transparent command frame instructing processing, waits for a response, transmits a transparent command frame instructing predetermined preprocessing for the first slave station, etc. The transparent command frame may be transmitted to a predetermined slave station in consideration of the processing status.

  Further, in the above embodiment, the case where the master station and the slave station are connected by bus and the ring network is configured by turning the line back at the stations located at both ends of the master station and the slave station is described. By connecting in a loop with a double line and looping back where the disconnection occurred, communication between the master station and the slave station connected via the line is continued, and the disconnection is restored. Even if it is a ring-type network in which the loopback is canceled when it is done, it can be applied.

In the above embodiment, the processes in steps S2 and S3 in FIG. 3 correspond to the preprocessing command frame transmitting means, the transparent command frame corresponds to the preprocessing command frame, and steps S4 to S in FIG. The processing in S7 corresponds to the line restoration processing means, and in the processing in step S4, the transparent command frame received from the loopback station as a response to the transparent command frame transmitted in the processing in step S3 corresponds to the response command frame.
Further, the process in step S23 in FIG. 4 corresponds to the preprocessing command relay means, and the processes in steps S24 and S25 correspond to the response relay means.
Further, in the process of step S3 in FIG. 3, the process of specifying the disconnection station from the storage information stored in the predetermined storage area in the process of step S1 when the disconnection state is notified corresponds to the disconnection station specifying means. .

It is a block diagram which shows an example of the ring type network system to which this invention is applied. It is an example of a frame format. It is a flowchart which shows an example of the process sequence of the master station at the time of a disconnection state detection. It is a flowchart which shows an example of the process sequence in the loopback station at the time of disconnection recovery. It is a flowchart which shows an example of the process sequence in a isolation | separation station. It is explanatory drawing explaining the flow of the frame from a disconnection state detection to disconnection recovery. It is explanatory drawing explaining the flow of the data in a ring type network system at each time from a disconnection state detection to disconnection recovery. It is explanatory drawing for demonstrating the state of a ring type network system when a disconnection state arises.

Explanation of symbols

M0 Master station SL1 to SL4 Slave station

Claims (4)

A ring network is constructed by one master station and a plurality of slave stations connected to the master station via a line and managed by the master station,
When any one of the stations detects a disconnection state in which communication with an adjacent station is disabled, communication is performed between the stations connected to the master station via the line by performing a loopback. Continue,
A ring in which the slave station disconnected from the master station by the loop back is reconnected to the master station via the line by releasing the loop back when recovery of the disconnected state is detected. Type network system,
When the recovery of the disconnection state is detected, the master station is set in advance as a state when the disconnected station is reconnected to the master station with respect to the disconnected station disconnected from the master station by the loopback. A preprocessing command frame transmitting means for generating a preprocessing command for shifting to the pre-return state and transmitting the command as a preprocessing command frame to the loopback station performing the loopback. ,
A line restoration processing means for instructing the loopback station to release the loopback and executing a predetermined line restoration process after a response command frame is notified as a response to the preprocessing command frame; With
The loopback station, when receiving the preprocessing command frame, preprocessing command frame relay means for transmitting the preprocessing command frame to the disconnecting station;
A response relay means for transmitting a response command frame received from the disconnecting station as a response to the preprocessing command frame to the master station, and
The ring network system according to claim 1, wherein, when receiving the preprocessing command frame, the disconnection station executes predetermined preprocessing according to the preprocessing command frame and transmits the response command frame. The state before return is set for each slave station according to the function of the slave station,
The master station comprises disconnection station specifying means for specifying the disconnection station to be reconnected to the master station by releasing the loopback when recovery of the disconnection state is detected,
The preprocessing command transmission means generates a preprocessing command corresponding to the pre-return state set for each disconnection station for each disconnection station specified by the disconnection station specifying means, 2. The ring network system according to claim 1, wherein the pre-processing command frame is transmitted in association with the disconnection station specified by the disconnection station specifying means.   3. The ring network according to claim 1, wherein the ring network is configured by connecting the master station and the slave station by a bus and turning back a line at stations located at both ends. system. A ring network is constructed by one master station and a plurality of slave stations connected to the master station via a line and managed by the master station,
Communicate between stations connected to the master station via the line by performing a loopback when any of the stations detects a disconnection state in which communication with an adjacent station is disabled. Continue
A ring in which the slave station disconnected from the master station by the loop back is reconnected to the master station via the line by releasing the loop back when recovery of the disconnected state is detected. Type network system recovery method,
When recovery from the disconnection state is detected, the master station sets in advance as a state when the disconnected station is reconnected to the master station with respect to the disconnected station disconnected from the master station by the loopback. Generating a preprocessing command for shifting to the pre-return state, and transmitting the command as a preprocessing command frame to the disconnecting station via the loopback station performing the loopback; ,
The disconnecting station that has received the preprocessing command frame performs a predetermined preprocessing according to the preprocessing command frame and transmits a response command frame to the preprocessing command frame;
The master station, after receiving the response command frame via the loopback station, instructing the loopback station to release the loopback and executing a process at the time of a predetermined line restoration; A method for restoring a ring network system, comprising:

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