JP2012074779A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system that does not make a communication error at a time of hot swap for changing joint modules of a robot and the like.SOLUTION: A master station of a communication system physically connects with a slave station at the highest level, electrically connects with the slave station at the highest level through a bus line, terminates the bus line, and communicates with a plurality of slave stations. In addition, each of the plurality of slave stations in the system connects the bus line with an upper station, and moreover switches the bus line between termination and connection with a lower station. In the lowest station, the bus line is terminated, and in slave stations other than the lowest station, the bus line is connected to a lower station connection connector. If a new slave station having the same function as a slave station is inserted under the lowest station, after the upper station connection connector of the new slave station is physically connected to the lower station connection connector of the lowest station, the lowest station receives an insertion instruction from the master station, and the lowest station switches the bus line from the terminal and connects to the upper station connection connector of a lower station.

Description

  The present invention relates to a communication system for hot-plugging or hot-plugging a terminal station that transmits and receives data in a time division manner.

  Conventionally, a system disclosed in Patent Document 1 has been known as a robot system that can cope with various work requests by combining a number of joint modules having simple shapes. In this system, first, a plurality of mechanically and electrically independent joint modules are combined and connected to each other. In this system, all the indirect modules connected are operated by transmitting and receiving data related to operation control using communication means provided in the joint module. As shown in FIG. 2 of Patent Document 1, the communication means in the joint module is configured to perform communication while being connected to the bus line. Therefore, even when a large number of joint modules are combined, the system uses a common bus line, so that it is possible to flexibly construct a robot system corresponding to the work content without increasing the number of internal wires. In addition, this robot system does not require a dedicated robot for each work. For this reason, for example, it can be said that the system is suitable for an automatic machine used for assembling a product of a small variety of products.

  By the way, in order to cause such a robot system to perform a work including a plurality of processes, the system prepares a plurality of joint module groups (robot hands) corresponding to each process, and replaces the robot hand every time the process is completed. Necessity comes out. This replacement operation should be avoided manually as it leads to a reduction in safety and productivity. For this reason, it is strongly desired that the system operate while autonomously exchanging the robot hand in accordance with the change of work contents. In order to realize this, the system needs to have a hot-line insertion / extraction function for changing the joint module without stopping its own system power supply.

  However, in the robot system described in Patent Document 1, when hot-swapping is performed, a communication error occurs in another joint module, and the system malfunctions. The first cause of this problem is noise generated during insertion / extraction. That is, if the joint module is inserted and removed while the bus line is in a live line state, noise is generated in the bus line. When this noise is superimposed on the communication signal of another joint module, a communication error occurs.

  The second cause is that the communication signal quality deteriorates due to the termination processing not being performed correctly. In bus communication, it is necessary to suppress the reflection of communication signals by terminating the end of the transmission path. When the joint module is inserted / removed, the joint module at the end is replaced. Therefore, it is necessary to change the termination process that has been performed at the end to another joint module. However, since this process is not taken into consideration in the robot system described in Patent Document 1, it is conceivable that signal quality deteriorates and a communication error occurs when the joint module is inserted and removed.

  As a technique for coping with the first cause, Patent Document 2 discloses an electrical connection relationship between an object to be inserted and a bus line at a timing that does not affect other communication in a system that transmits and receives data in a time division manner. A technique for switching is disclosed. Also, as a countermeasure technique for the second cause, Patent Document 3 discloses a technique in which the lowest station adaptively performs transmission line termination processing in a bus communication system configured by daisy chain connection.

JP 09-029671 A Japanese Patent Laid-Open No. 11-261667 Japanese Patent Laid-Open No. 04-326832

  The technique disclosed in Patent Document 2 is effective as a technique for suppressing noise generated by a driver that drives a communication signal, but it cannot suppress noise generated when a connector pin is connected or disconnected. For this reason, when inserting / removing, there still remains a problem that noise occurs on the bus line and a communication error occurs. Furthermore, in the system of Patent Document 2, it is necessary to separately provide a signal line for notifying the connection switching means between the insertion / extraction object and the bus line. In a robot system, an increase in the number of wires reduces the degree of freedom of bending of the joint, so an increase in the number of wires should be avoided.

  In addition, since the technology disclosed in Patent Document 3 does not consider insertion / removal in a live line state, signal quality is significantly reduced until termination processing is switched after insertion / removal. Will cause an error.

  That is, even if the techniques disclosed in Patent Documents 1 to 3 described above are used, a communication error occurs during hot-swap, and thus a system capable of autonomously exchanging joint modules while operating the system is realized. Is difficult.

  Therefore, this invention provides the communication system which does not produce a communication error at the time of hot-line insertion and removal for exchanging joint modules, such as a robot.

In order to solve such a problem, the communication system of the present invention is a communication system that performs transmission / reception between a parent station and a plurality of slave stations connected in order from the upper level to the lower level. Of the stations, a slave station connection connector for connecting to the top slave station, a bus line electrically connected to the top slave station, a master station side termination means for terminating the bus line, Communication means for communicating with each of a plurality of slave stations through the bus line, each of the plurality of slave stations having an upper station connection connector for connecting the bus line to an upper station, and the bus line The lower station connection connector for connecting to the lower station, the slave station side termination means for terminating the bus line, and the lower station connection to the bus line from the upper station connection connector based on the instruction information from the parent station Connector or A switch means for connecting by switching the station side termination means comprises,
The switch means of the lowest station of the plurality of slave stations is in a state where the bus line is connected to the slave station side termination means, and the switch means of a slave station other than the lowest station is connected to the bus line. In the state connected to the lower station connector,
When a new slave station having the same function as the slave station is inserted into the lowest station, a higher station connection connector of the new slave station is physically connected to a lower station connection connector of the lowest station Thereafter, the lowest station receives an insertion instruction from the master station, and the switch means of the lowest station connects the bus line from the slave station side termination means to the lower station connection connector.

  In a robot system that autonomously replaces a joint module, a communication system that does not cause a communication error at the time of hot-swapping to replace the joint module can be provided.

The figure which shows the structure of the whole robot system. The figure which shows the structure of a flame | frame. The figure which shows allocation of slot information. The figure which shows the function structure of a master station. The figure which shows allocation of the slot information in case the sub_station | mobile_unit D is inserted. The figure which shows allocation of the slot information in the case of extracting the slave station C. The figure which shows the function structure of a sub_station | mobile_unit. The figure which shows the operation | movement flow of the system in the case of inserting a slave station. The figure which shows the operation | movement flow of the system in the case of extracting a slave station. The figure which shows the structure of the robot system which inserts / extracts a some slave station. The figure which shows the function structure of a sub_station | mobile_unit. The figure explaining the detection of insertion / extraction.

<Embodiment 1>
FIG. 1 is a diagram illustrating a configuration of a communication system such as a robot according to the first embodiment. In the present embodiment, as shown in FIG. 1, it is assumed that a master station and a plurality of slave stations are connected in order from the upper level to the lower level to constitute a system. As will be described later, the communication means provided in the master station and the plurality of slave stations are connected by a single bus line which is a common bus line. Note that a slave station close to the master station when viewed from any slave station is called an upper station, and a slave station far from the master station is called a lower station.

  The master station 200 transmits motor control information to the slave stations A to C. The parent station 200 is provided with a higher-level station connection connector 201 of a child station, and is connected to a higher-level station connection connector 211 of a child station A that is the highest-level child station.

  Each of the slave stations A, B, and C is a joint module that is a component of the robot system. The slave stations A, B, and C are provided with upper station connection connectors 211 to 231 and lower station connection connectors 212 to 232, and are connected to the upper station and the lower station via these.

  The slave stations A, B, and C are connected to motors 213, 223, and 233 for bending the joints and angle sensors 214, 224, and 234 for detecting the bending angles of the joints.

  The motor control information transmitted from the master station 200 includes voltage values to be applied to the motors 213, 223, and 233, for example. The slave stations A, B, and C drive the motors 213, 223, and 233 based on the received motor control information. Further, the slave stations A and B acquire joint bending angles from the angle sensors 214, 224, and 234, respectively, and transmit them to the master station 200 as angle information. The master station 200 generates the next motor control information according to the received angle information. In this embodiment, feedback control of the entire system is performed by performing such communication and motor control at regular intervals.

  FIG. 2 is a diagram illustrating an example of a frame configuration used for communication between terminal stations. In this embodiment, time division communication is performed between stations by a TDMA (Time Division Multiple Access) method. As shown in FIG. 2, a frame having a certain time length is divided into M time slots 0 to M-1 having a certain time width. In time slot 0 at the beginning of the frame, slot information of the frame is transmitted from the master station 200 to the slave stations A, B, and C. The slot information here is information indicating which terminal station is assigned to which time slot and performs data transmission / reception. In the present embodiment, for example, information shown in FIG. 3 is transmitted as slot information. In the example of FIG. 3, time slots 1 to 3 are allocated for transmitting motor control information from the master station 200 to the slave stations A, B, and C. Each of the time slots 4 to 6 is assigned to transmit angle information from the slave stations A, B, and C to the master station 200. Other time slots are empty slots in which communication is not performed.

  FIG. 4 is a diagram illustrating an internal configuration of the master station 200 of the present embodiment. The motor control information generation unit 501 generates motor control information corresponding to the system operation. Further, the next motor control information is generated according to the angle information transmitted from the slave stations A, B, and C during the system operation.

  The insertion / extraction instruction information generation unit 502 generates insertion instruction information to be transmitted to an upper station adjacent to a new child station when a new child station is inserted into the system. For example, when the slave station D is inserted into the configuration up to the slave station C so far, insertion instruction information to be transmitted to the upper slave station C adjacent to the new slave station is generated. When the slave station is removed from the system configuration, the removal instruction information generation unit 502 of the parent station 200 generates removal instruction information to be transmitted to the upper station adjacent to the child station to be removed. For example, when the slave station C is removed from the configuration up to the slave station C so far, the removal instruction information generation unit 502 of the master station 200 provides the removal instruction information to be transmitted to the upper slave station B adjacent to the slave station C. Produces.

  The slot information generation unit 503 generates the aforementioned slot information. When the insertion instruction information or the extraction instruction information is input from the insertion / extraction instruction information generation unit 502, the slot information generation unit 503 uses the time slot that was an empty slot in the previous frame to insert the insertion instruction information or the extraction instruction information. Generate slot information to be transmitted.

  FIG. 5 shows an example of slot information when a new slave station D is inserted into the configuration up to the slave station C in the system shown in FIG. When the slave station D is inserted, the time slot is set so that the insertion instruction information is transmitted from the master station 200 to the slave station C using the time slot 7 that was an empty slot in the previous frame as shown in FIG. Assigned.

  FIG. 6 is an example of slot information when the slave station C is removed from the configuration up to the slave station C in the system shown in FIG. When the slave station C is extracted, the time slot is set so that the extraction instruction information is transmitted from the master station 200 to the slave station B using the time slot 7 that was an empty slot in the previous frame as shown in FIG. Assigned. Note that the time slot allocated to transmit the insertion instruction information and the extraction instruction information is not limited to the time slot 7 and may be any time slot as long as it is in an empty slot.

  The transmission / reception timing control unit 504 controls the communication timing of the communication unit 505 based on the slot information input from the slot information generation unit 503. Further, the communication unit 505 converts the motor control information, insertion instruction information or removal instruction information, and slot information into communication signals based on the control of the transmission / reception timing control unit 504, and transmits the communication signals to the slave stations A, B, and C. In addition, angle information transmitted from the slave stations A, B, and C is received.

  As shown in FIG. 4, the master station 200 is connected to the slave station A via a slave station connection connector 506. The slave station connection connector 506 is connected to the communication unit 505. When the master station 200 and the slave station are connected, the communication unit 505 of the master station 200 and the communication unit of the slave station are connected by a single bus line. It becomes the composition which is done. The terminator 507 performs termination on the master station side of the bus line.

  The slave station of this embodiment will be described. FIG. 7 is a diagram showing a functional configuration inside the slave station A. As shown in FIG. The slot information storage unit 101 stores the slot information received from the master station 200, and outputs the slot information to the transmission / reception timing control unit 102 and the switch timing control unit 109. When slot information is not received from the master station 200, that is, when the slave station A is not connected to the bus line, the slot information storage unit 101 stops outputting slot information.

  The transmission / reception timing control unit 102 controls the communication timing of the communication unit 103 for slave station communication based on the slot information input from the slot information storage unit 101. The communication unit 103 receives angle information transmission to the master station 200 based on control of the transmission / reception timing control unit 102, and receives motor control information, insertion instruction information, removal instruction information, slot information, etc. transmitted from the parent station 200. To do. The motor drive unit 104 drives an externally connected motor based on the motor control information transmitted from the master station 200. The angle information generation unit 105 acquires a bending angle from an angle sensor connected to the outside, and generates angle information.

  The slave station A is connected to the master station 200 via the upper station connection connector 106 and is connected to the slave station B via the lower station connection connector 107. When the switch 108 is controlled to connect the upper station connection connector 106 and the lower station connection connector 107, the communication unit 505 of the master station 200 and the communication unit 103 of the slave station A and the slave station B have a single Connected to the bus line. If there is no slave station connected to other than the slave station of A, the slave station A becomes the lowest station. In this case, the switch 108 switches the bus line to the terminator 110 and connects it. In this way, the slave station side termination is performed.

  The switch 108 electrically connects the upper station connection connector 106 to either the lower station connection connector 107 or the terminator 110 based on the connection control signal output from the switch timing control unit 109. When the switch timing control unit 109 receives the insertion instruction information from the master station 200, the upper station connection connector 106 and the lower station connection connector 107 are electrically connected at any timing of the empty slot shown in FIG. A connection control signal is output to the switch 108. Further, when the removal instruction information is received from the master station 200, the switch 108 is set so that the upper station connection connector 106 and the terminator 110 are electrically connected at any timing of the empty slot shown in FIG. Control.

  The switch timing control unit 109 switches so that the upper station connection connector 106 and the terminator 110 are electrically connected when no slot information is input and the slave station A is not connected to the bus line. 108 is controlled. The internal configurations and operations of the other slave stations B and C are the same as those of the slave station A. Therefore, the description of the internal configuration and operation of the slave stations B and C is omitted.

  Next, the insertion / extraction operation of the slave station will be described. First, the operation for inserting / removing a single slave station will be described. This is an operation assumed when the joint module is changed in accordance with, for example, a change in work content.

  FIG. 8 shows an operation flow of each station when a slave station D as a new slave station is inserted into the system. In the insertion operation of the present embodiment, the slave station D is arranged at a predetermined position. When the slave station C is moved to this position, the slave station C is connected to the slave station C by an appropriate mechanical holding mechanism (not shown). A configuration is adopted in which D is inserted. In general, it is assumed that the inserted slave station switch 108 is always connected to the terminator 110.

  In S801, the slave station D having the same function as the new slave station is inserted into the slave station C which is the lowest slave station. The insertion at this time may be performed by an external device based on an instruction from the master station, or may be performed by a user's manual. Then, the master station detects the insertion of the slave station D or receives a notice from the user. The switch 108 of the slave station C is controlled so that the upper station connector 106 and the terminator 110 are electrically connected. The slave station D is not yet electrically connected to the bus line. Therefore, first, the switch 108 of the slave station D is controlled so that the upper station connector 106 and the terminator 110 are electrically connected. Further, since the slave station D is not yet electrically connected to the bus line, the influence of noise or the like due to the insertion of the slave station D does not occur on the bus line.

  In S802, since the master station 200 has detected the insertion of the slave station D, the slave station C230, which is electrically connected to the bus line, sends insertion instruction information to the slave station C230, which is the lowest station. Send. As described above, the insertion instruction information is transmitted based on the slot allocation information shown in FIG.

  In step S <b> 803, the slave station C receives insertion instruction information from the master station 200. In S804, the slave station C controls the switch 108 so that the upper station connection connector 106 and the lower station connection connector 107 are electrically connected at the timing of the empty slot. As a result, the slave station D becomes the lowest station connected to the bus line. Then, by inserting the slave station D, the slave station that performs the termination process is changed from the slave station C to the slave station D, and the termination process of the bus line is correctly performed. Accordingly, when viewing the state of the switch 108 from the slave station A to the slave station D, the slave stations other than the lowest station of the slave station D are all connected to the lower station connector.

  In S805, the master station 200 confirms that the slave station D is connected to the bus line, and ends the operation. Confirmation of the slave station connected to the bus line is performed, for example, when the slave station C that has performed switching control of the switch 108 notifies the master station 200 to that effect. In this case, after the slave station C controls the switch 108, it notifies the master station 200. Then, the master station 200 receives the notification from the slave station C and recognizes that the slave station D is connected to the bus line. The notification from the slave station C that has performed switching control to the master station 200 may use a time slot that was an empty slot in the previous frame, in addition to using the assigned time slot.

  When the slave station D is inserted into the system by the operation of these stations, the slave station D is electrically connected at the timing of an empty slot where communication with other stations is not performed. In addition, termination processing is performed in the slave station D which is the lowest in place of the slave station C. As a result, it is possible to insert a new slave station D into the system without affecting the communication of other stations.

  Next, the operation of each station when the slave station C is removed from the system shown in FIG. 1 will be described with reference to the operation flowchart of FIG. In the extraction operation of this embodiment, after the slave station C is moved to a predetermined position, the slave station C is extracted from the slave station B that is an upper slave station adjacent to the slave station C by an appropriate mechanical holding mechanism (not shown). Shall.

  In step S <b> 901, the master station 200 transmits the extraction instruction information to the slave station B that is an upper station adjacent to the slave station C. As described above, the removal instruction information is transmitted based on the slot allocation information shown in FIG. In step S <b> 902, the slave station B receives the extraction instruction information from the master station 200. In S903, the slave station B controls the switch 108 so that the upper station connection connector 106 and the terminator 110 are electrically connected at the timing of the empty slot 7 shown in FIG. As a result, the slave station C is disconnected from the bus line, and at the same time, the slave station that performs the termination process is changed from the slave station C to the slave station B, and the termination process of the bus line is performed correctly. In S904, the slave station C is physically removed from the slave station B. Removal of the slave station C may be performed by an external device according to an instruction from the master station, or may be manually performed by a user.

  As described above, when the slave station C is removed from the system by the operation of each station, the slave station C is electrically disconnected at the timing of an empty slot where communication with other stations is not performed. Then, termination processing is performed in the slave station B which is the lowest station connected to the bus line. As a result, the slave station can be removed from the system without affecting the communication of other stations. Note that after the slave station C is removed, the upper slave station B adjacent to the removed slave station C may notify the master station 200 to that effect.

  The operation when a plurality of slave stations are simultaneously inserted and removed will be described below. For example, as shown in FIG. 10, it is assumed that a combination of a slave station D and a slave station E is prepared as one robot hand, and this is inserted into and removed from the system according to the work contents. The operation in this case is also performed according to the operation flow shown in FIGS.

  First, the operation when the slave station D and the slave station E are inserted into the system will be described. In S901, the master station receives an instruction to add the slave station D and the slave station E to the slave station C that is the lowest station from the outside. For example, the slave station D and the slave station E are physically inserted into the slave station C, which is the lowest station, by an external device in accordance with an instruction from the master station. Here, the switches 108 of the slave station D and the slave station E are not connected to the bus line. That is, the switches 108 of the slave station D and the slave station E are both connected to the terminator 110. In the following steps, control is performed so that the upper station connector 106 and the terminator 110 are electrically connected.

  In S902, the master station 200 transmits insertion instruction information to the slave station C that is the lowest station among the slave stations electrically connected to the bus line. In S903, the slave station C, which is the lowest station among the slave stations electrically connected to the bus line, receives the insertion instruction information from the master station 200. In S904, the slave station C controls the switch 108 so that the upper station connection connector 106 and the lower station connection connector 107 are electrically connected, for example, at the timing of the empty slot 7 in FIG. As a result, the switch 108 of the slave station C is connected to the lower station connection connector 107, and the bus line of the slave station D1010 is connected to the bus line of the slave station C230. Further, the slave station that performs the termination process is changed from the slave station C to the slave station D.

  In S905, the master station 200 confirms that the slave station D is electrically connected to the bus line. Then, the master station 200 confirms that the slave station E is not yet electrically connected to the bus line, returns to step S902, and the operations in steps S902 to S904 are now performed for the slave station D. Done. Thereby, the bus line of the slave station E and the bus line of the slave station D are connected, and the termination process is performed in the slave station E. In S905, the master station 200 confirms that the slave station D and the slave station E are electrically connected to the bus line, and ends the operation.

  As described above, even when a plurality of new slave stations are inserted into the system at the same time, the new slave stations are electrically connected using the timings of the empty slots where communication with other stations is not performed. Further, termination processing is performed in the lowest station E instead of the slave station C. As a result, it can be seen that a plurality of new slave stations can be simultaneously inserted into the system without affecting the communication of other stations.

  Next, the operation when the slave station D and the slave station E are simultaneously removed from the system will be described. At the time of extracting a plurality of slave stations, the master station 200 selects the highest slave station, the slave station D, from the plurality of slave stations to be extracted. A description will be given according to the flow of extracting the slave station D and the slave station E shown in FIG.

  In step S <b> 901, the master station 200 transmits the extraction instruction information to the slave station C that is an upper station adjacent to the slave station D. In step S <b> 902, the slave station C receives the extraction instruction information from the master station 200. In S903, the slave station C controls the switch 108 so that the upper station connector 106 and the terminator 110 are electrically connected, for example, at the timing of the empty slot 7 in FIG. As a result, the slave station D and the slave station E are disconnected from the bus line. In addition, the slave station that performs the termination process moves from the slave station E to the slave station C. In S904, the slave station D is physically removed from the slave station C230.

  As described above, even when a plurality of slave stations are removed from the system at the same time, the slave stations are electrically disconnected at the timing of an empty slot where communication with other stations is not performed. Further, in place of the slave station E, the termination process is performed in the slave station C which is the lowest station. As a result, it is understood that a plurality of slave stations can be removed from the system at the same time without affecting the communication of other stations.

  As described above, by adopting the configuration of the first embodiment, it is possible to perform hot-swapping of a slave station from the system without affecting the communication of other slave stations while operating the system. It becomes. As a result, it is possible to realize a highly safe and productive robot system that can autonomously recombine each joint module as a slave station.

<Embodiment 2>
In the second embodiment, even when the user physically inserts or removes the slave station without going through the system or when the function of the slave station is impaired due to a failure or the like during the system operation, Explain that it is possible to stably perform communication of the slave stations. Thereby, even when a slave station is inserted and removed at an unexpected timing of the system, it is possible to realize a highly safe robot system that does not cause a malfunction.

  FIG. 11 shows the configuration of the internal functions of the slave station in this embodiment. The same reference numerals as those in FIG. 1 are attached to blocks indicating the internal configuration of the slave station of the first embodiment, and the description of the blocks is omitted. As shown in FIG. 11, the insertion / extraction detection unit 1101 is for detecting the connection state between the lower station connector 107 and the lower station connector. The insertion / removal detection unit 1101 detects the insertion of the lower station by inserting the lower station and electrically connecting the own station and the communication line of the lower station. Conversely, when a lower station is removed from the lower station connection connector 107, the mechanical state of the connector is electrically monitored before the communication line between the own station and the lower station is electrically disconnected. Detects removal of subordinate stations. Then, the insertion / extraction detection unit 1101 outputs an insertion detection signal to the switch timing control unit 1102 at the time of detection of insertion and an extraction detection signal at the time of detection of extraction.

  FIG. 12 shows the configurations of the upper station connection connector 106, the lower station connection connector 107, and the insertion / extraction detection unit 1101 that enable the above insertion / extraction detection.

  In FIG. 12, male pins 1201 and 1202 are communication line connection pins provided in the lower station connection connector 107. The male pins 1201 and 1202 are connected to the switch 108 via signal lines 1203 and 1204. Male pins 1205 and 1206 are insertion / extraction detection pins provided in the lower-level station connection connector 107. The male pins 1205 and 1206 are connected to the insertion / extraction detection unit 1101 through signal lines 1207 and 1208.

  Female pins 1209 and 1210 are communication line connection pins provided in the upper station connection connector 106. The female pins 1209 and 1210 are connected to the switch 108 and the communication unit 103 via signal lines 1211 and 1212. The female pins 1213 and 1214 are insertion / extraction detection pins provided in the upper station connector 106. Female pins 1213 and 1214 are connected via a signal line 1215.

  The insertion / extraction detection unit 1101 outputs an insertion detection signal to the switch timing control unit 1102 when the signal line 1207 and the signal line 1208 are in a short circuit state. Further, when the signal line 1207 and the signal line 1208 are in an open state, an extraction detection signal is output to the switch timing control unit 1102.

  Here, as shown in FIG. 12, the lengths of the male pins 1201 and 1202 for connecting the communication line are set longer than the male pins 1205 and 1206 for detecting insertion / removal. With this setting, when the upper station connection connector 106 is inserted into the lower station connection connector 107, the signal line 1207 and the signal line 1208 are short-circuited after the communication lines of the upper station and the lower station are connected. On the other hand, when the higher station connection connector 106 is removed from the lower station connection connector 107, the signal line 1207 and the signal line 1208 are opened before the communication line between the upper station and the lower station is disconnected. As a result, when a lower station is inserted, the insertion / extraction detection unit 1101 can output an insertion detection signal after the communication lines of the own station and the lower station are electrically connected. Further, when the lower station is removed, the insertion / removal detection unit 1101 can output the removal detection signal before the communication line between the own station and the lower station is electrically disconnected.

  Next, returning to FIG. 11, the switch timing control unit 1102 controls the switch 108 in accordance with the input from the insertion / extraction detection unit 1101 in addition to the operation of the first exemplary embodiment. When the insertion detection signal is input from the insertion / extraction detection unit 1101, the switch timing control unit 1102 controls the switch 108 in the same manner as when the insertion instruction information is received from the master station 200. When a removal detection signal is input from the insertion / removal detection unit 1101, the switch 108 is controlled in the same manner as when removal instruction information is received from the master station 200. As in the first embodiment, when no slot information is input from the slot information storage unit 101, the switch timing control unit 1102 controls the switch 108 so that the upper station connection connector 106 and the terminator 110 are electrically connected. To do.

  Next, the operation when the switch 108 is controlled by the insertion / extraction detection of the insertion / extraction detection unit 1101 in the system configuration shown in FIG. 10 will be described. This corresponds to the operation when the slave station is inserted / removed at an unexpected timing when the system inserts / removes the slave station or when the slave station is disconnected due to a failure or the like. To do.

  First, a case where the slave station D and the slave station E are simultaneously inserted into a system in which the master station 200 to the slave stations A, B, and C are connected will be described. The slave station D and the slave station E do not receive slot information from the slot information storage unit 101 before insertion. For this reason, the switches 108 of the slave station D and the slave station E are controlled so as to electrically connect the upper station connection connector 106 and the terminator 110.

  When the slave station D is inserted into the slave station C, the insertion / extraction detection unit 1101 of the slave station C outputs an insertion detection signal to the switch timing control unit 1102. Thereafter, the switch 108 of the slave station C is controlled to electrically connect the upper station connection connector 106 and the lower station connection connector 107 at the timing of the empty slot. As a result, the slave station D is electrically connected to the bus line and can receive slot information from the master station 200.

  A slave station E is inserted in the slave station D. Therefore, the switch timing control unit 1102 of the slave station D is in a state where an insertion detection signal is input from the insertion / extraction detection unit 1101. Therefore, when the slot information is input to the switch timing control unit 1102 of the slave station D, the upper station connection connector 106 and the lower station connection connector 107 are electrically connected, for example, at the timing of the empty slot 7 in FIG. The switch 108 is controlled as described above. As a result, the slave station E1020 is electrically connected to the bus line, and the insertion operation of the slave station D and the slave station E is completed.

  Next, the operation when the slave station D and the slave station E are simultaneously removed from the system will be described. When the slave station D is removed from the slave station C, an extraction detection signal is output from the insertion / extraction detection unit 1101 of the slave station C to the switch timing control unit 1102 before the electrical connection between the slave stations is disconnected. Then, the switch timing control unit 1102 of the slave station C controls the switch 108 to electrically connect the upper station connection connector 106 and the terminator 110 at the timing of the empty slot 7. Here, the switch timing control unit 1102 until the disconnection detection signal is input until the electrical connection between the lower station connection connector 107 of the slave station C and the upper station connection connector 106 of the slave station D1010 is disconnected. The control of the switch 108 must be completed. That is, an empty slot needs to exist between the time when the removal detection signal is input and the time when the electrical connection is disconnected. For this, the time length of the frame is made sufficiently short (for example, 1 msec). If it is set, it can be operated practically without any problem.

  By the operation of each part in the second embodiment as described above, even when the user inserts / removes the slave station during the system operation, or when the slave station is disconnected due to a failure or the like, the influence of the insertion / extraction is different. Other slave stations can perform stable communication without affecting the communication of the slave stations. Therefore, when insertion / extraction is performed at an unexpected timing of the system, it becomes possible for the master station to receive the detection information and transmit a system operation stop command to the slave station to safely stop the system. .

  In the first and second embodiments, the stations are directly connected in cascade using connectors, but the present invention is not limited to this. For example, the present invention can also be applied to a configuration in which the stations are connected in cascade by a cable, that is, a communication system in which a plurality of stations are connected in a daisy chain.

Claims (6)

A communication system that performs transmission and reception between a master station and a plurality of slave stations connected in order from the top to the bottom,
The master station is
Of the plurality of slave stations, a slave station connector for connecting to the top slave station,
A bus line electrically connected to the uppermost slave station;
Master station side termination means for terminating the bus line;
Communication means for communicating with each of the plurality of slave stations through the bus line;
With
Each of the plurality of slave stations is
An upper station connection connector for connecting the bus line to an upper station;
A subordinate station connection connector for connecting the bus line to a subordinate station;
Slave station side termination means for terminating the bus line;
Switch means for switching and connecting the electrically connected bus line from the upper station connection connector to the lower station connection connector or the slave station side termination means based on the instruction information from the parent station;
With
The switch means of the lowest station of the plurality of slave stations is in a state where the bus line is connected to the slave station side termination means, and the switch means of a slave station other than the lowest station is connected to the bus line. In the state connected to the lower station connector,
When a new slave station having the same function as the slave station is inserted into the lowest station, a higher station connection connector of the new slave station is physically connected to a lower station connection connector of the lowest station Thereafter, the lowest station receives an insertion instruction from the master station, and the switch means of the lowest station connects the bus line from the slave station side termination means to the lower station connection connector. Communications system.   When the lowest station is removed from the plurality of slave stations, an upper slave station adjacent to the lowest station receives an removal instruction from the parent station, and the switch means of the higher slave station includes the bus line. The upper station connection connector of the lowest station is physically removed from the lower station connection connector of the upper station after connecting the lower station connection connector to the slave station side termination means. The communication system according to 1.   The said communication means of the said master station is provided with the production | generation means which produces | generates the slot which transmits the said insertion instruction | indication and the said removal instruction | indication by time division with respect to each of these several slave stations. The communication system described. A communication system that performs transmission and reception between a master station and a plurality of slave stations connected in order from the top to the bottom,
The master station is
Of the plurality of slave stations, a slave station connector for connecting to the top slave station,
A bus line electrically connected to the uppermost slave station;
Master station side termination means for terminating the bus line;
Communication means for communicating with each of the plurality of slave stations via the bus line;
With
Each of the plurality of slave stations is
An upper station connection connector for connecting the bus line to an upper station;
A subordinate station connection connector for connecting the bus line to a subordinate station;
Slave station side termination means for terminating the bus line;
Detecting means for detecting a connection state between the lower station connection connector and an upper station connection connector of an adjacent slave station;
According to the connection state of the detection means, the bus line from the higher station connection connector, switch means for switching and connecting to the lower station connection connector or the slave station side termination means,
With
In the plurality of slave stations, the switch means of the lowest station is in a state where the bus line is connected to the slave station side termination means, and the switch means of a slave station other than the lowest station is the bus line Is connected to the subordinate station connector,
When a new slave station having the same function as the slave station is inserted into the lowest station, the detection means of the lowest station is inserted into the lower station connection connector of the higher station connection connector of the new slave station. And the switch means of the lowest station connects the bus line from the slave station side termination means to the lower station connection connector based on the detection.   When the lowest station is removed from the plurality of slave stations, the detection means of the upper slave station adjacent to the lowest station removes the upper station connection connector of the lowest station from the lower station connection connector. 5. The switch according to claim 4, wherein the switching means of the upper slave station connects the bus line from the lower station connection connector to the slave station side termination means based on the detection. Communications system. Each of the plurality of slave stations further includes a slave station communication means for communicating with the master station via a bus line,
When the switch means of any of the plurality of slave stations changes connection, the slave station communication means of any of the plurality of slave stations notifies the master station to that effect. The communication system according to claim 5.

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