JP4728362B2 - Node identifier setting method for communication system - Google Patents

Description

  The present invention relates to a node identifier setting method of a communication system that assigns a node identifier to a slave node of a communication system in which a master node and a slave node exist, and in particular, even if the number of connected slave nodes changes, The node identifier to the slave node can be set without changing the setting.

  As a node identifier setting method of a conventional communication system, various methods for assigning a node identifier to a slave node in the communication system are shown. For example, as a method of assigning a node identifier to a node connected on a communication bus, a master (refers to a side that determines a node identifier. The same applies to the following, so this description will be omitted as appropriate) a node and a slave (the node identifier is (This is the same in the following, and this description will be omitted as appropriate.) The node has the same node identifier list in advance. Next, the slave node selects one node identifier from the node identifier list that it holds.

  Next, the master node selects one node identifier from the node identifier list that it holds and transmits it to all nodes. Next, the slave node responds if the same node identifier selected by itself is transmitted. Next, the slave node monitors responses from other slave nodes, and if the responding slave node is the only one, it determines the node identifier as a unique node identifier of the own slave node. Next, if there are other slave nodes that responded, the slave node reselects another node identifier. Next, the master node transmits in the order of the node identifier list that it holds, and determines the node identifiers of all the slave nodes (see, for example, Patent Document 1).

  As a node identifier setting method of a communication system that assigns a node identifier to a node connected to another communication bus, a master node transmits a request message, and a slave node that receives the request message sets based on a random variable. During the monitoring time, it waits for a response message to be sent. Next, when a response message is not transmitted from another slave node during the monitoring time, the slave node sets the received node identifier as a unique node identifier of the slave node, and transmits the response message (for example, patent Reference 2).

JP 2000-165437 A JP-A-2005-341386

In the present invention, one master node and one or a plurality of slave nodes are connected by a communication bus, and the master node and one or a plurality of slave nodes use a notification line for notifying a node identifier setting status. A node identifier setting method for a communication system connected in a ring shape with a daisy chain connection,
The master node outputs a setting start signal to a slave node connected later on the notification line, and the slave node that has input the setting start signal from the notification line stops message transmission on the communication bus and When a setting start signal is output to a slave node or a master node that is connected later, and the master node receives a setting start signal from a slave node that is connected before on the notification line, the master node is again connected later on the notification line. A first step of outputting a setting start signal to the slave node again and transmitting a request message for setting the node identifier to the slave node on the communication bus;
The slave node that has input the setting start signal from the notification line receives the request message flowing on the communication bus, sets the node identifier requested in the request message as a unique node identifier of its own slave node, A second step of transmitting a response message indicating that the node identifier has been set to the node and outputting a setting start signal to a slave node or a master node connected later on the notification line;
If the master node receives a response message and does not receive a setup start signal from a previously connected slave node on the notification line, it sends another request message on the communication bus and returns to the second step;
The master node includes a third step of receiving the response message and ending the node identifier setting when receiving the setting start signal from the slave node previously connected in the notification line.

In the node identifier setting method of the communication system according to the present invention, one master node and one or a plurality of slave nodes are connected via a communication bus, and the master node and one or a plurality of slave nodes are set to a node identifier. A node identifier setting method for a communication system that is connected in a ring shape in a daisy chain connection with a notification line that notifies the situation,
The master node outputs a setting start signal to a slave node connected later on the notification line, and the slave node that has input the setting start signal from the notification line stops message transmission on the communication bus and When a setting start signal is output to a slave node or a master node that is connected later, and the master node receives a setting start signal from a slave node that is connected before on the notification line, the master node is again connected later on the notification line. A first step of outputting a setting start signal to the slave node again and transmitting a request message for setting the node identifier to the slave node on the communication bus;
The slave node that has input the setting start signal from the notification line receives the request message flowing on the communication bus, sets the node identifier requested in the request message as a unique node identifier of its own slave node, A second step of transmitting a response message indicating that the node identifier has been set to the node and outputting a setting start signal to a slave node or a master node connected later on the notification line;
If the master node receives a response message and does not receive a setup start signal from a previously connected slave node on the notification line, it sends another request message on the communication bus and returns to the second step;
When the master node receives the response message and receives the setting start signal from the slave node previously connected in the notification line, the master node includes a third step for ending the node identifier setting. Node identifiers can be set for all slave nodes without change, and the node identifier setting time can be reduced.

In the present invention, one master node and one or a plurality of slave nodes are connected by a communication bus, and the master node and one or a plurality of slave nodes use a notification line for notifying a node identifier setting status. A node identifier setting method for a communication system connected in a ring shape with a daisy chain connection,
A first step in which a master node outputs a setting start signal to a slave node connected later on a notification line and transmits a request message for setting a node identifier to the slave node on the communication bus;
The slave node that has input the setting start signal from the notification line receives the request message flowing on the communication bus, sets the node identifier requested in the request message as a unique node identifier of its own slave node, A second step of transmitting a response message indicating that the node identifier has been set to the node and outputting a setting start signal to a slave node or a master node connected later on the notification line;
If the master node receives a response message and does not receive a setup start signal from a previously connected slave node on the notification line, it sends another request message on the communication bus and returns to the second step;
The master node includes a third step of receiving the response message and ending the node identifier setting when receiving the setting start signal from the slave node previously connected in the notification line.

In the node identifier setting method of the communication system according to the present invention, one master node and one or a plurality of slave nodes are connected via a communication bus, and the master node and one or a plurality of slave nodes are set to a node identifier. A node identifier setting method for a communication system that is connected in a ring shape in a daisy chain connection with a notification line that notifies the situation,
A first step in which a master node outputs a setting start signal to a slave node connected later on a notification line and transmits a request message for setting a node identifier to the slave node on the communication bus;
The slave node that has input the setting start signal from the notification line receives the request message flowing on the communication bus, sets the node identifier requested in the request message as a unique node identifier of its own slave node, A second step of transmitting a response message indicating that the node identifier has been set to the node and outputting a setting start signal to a slave node or a master node connected later on the notification line;
If the master node receives a response message and does not receive a setup start signal from a previously connected slave node on the notification line, it sends another request message on the communication bus and returns to the second step;
When the master node receives the response message and receives the setting start signal from the slave node previously connected in the notification line, the master node includes a third step for ending the node identifier setting. Node identifiers can be set for all slave nodes without change, and the node identifier setting time can be reduced.

Embodiment 1 FIG.
Embodiments of the present invention will be described below. 1 is a diagram showing a configuration of a communication system according to Embodiment 1 of the present invention, FIG. 2 is a flowchart for explaining a node identifier setting method of the communication system shown in FIG. 1, and FIG. 3 is a communication shown in FIG. 4 is a flowchart for explaining the operation of the master node in the node identifier setting method of the system, and FIG. 4 is a flowchart for explaining the operation of the slave node in the node identifier setting method of the communication system shown in FIG.

  In the figure, a master node 21, a slave node A22, a slave node B23, and a slave node C24 are connected to the communication bus 11 to form a network. Further, the master node 21, the slave node A22, the slave node B23, and the slave node C24, for example, output a digital status on the notification line 12 that notifies the status of the node identifier setting formed by a digital input / output line. 32, 34, 36, 38 and digital inputs 31, 33, 35, 37 are connected in a daisy chain connection and in a ring shape. In addition to those shown in the figure, the apparatus and configuration necessary for the communication system of the network are included.

  A node identifier setting method of the communication system of the first embodiment configured as described above will be described based on the flowcharts of FIGS. First, when the communication system is initialized by power-on or reset, node identifier setting is started. Next, the master node 21 outputs the setting start signal from the notification line 12 by logically inverting the output value of the digital output 32 from the current value. Then, the master node 21 transmits a request message for setting a node identifier to the slave node A22 connected later on the notification line 12 on the communication bus 11 (step S11 in FIG. 2).

  Next, by detecting that the input value of the digital input 33 is logically inverted, the slave node A 22 that has input the setting start signal from the notification line 12 receives the request message flowing on the communication bus 11. Then, the node identifier requested by the request message is set as a unique node identifier of the own slave node A22. Then, a response message indicating that the node identifier has been set is transmitted onto the communication bus 11. The slave node A22 outputs a setting start signal from the notification line 12 by logically inverting the output value of the digital output 34 from the current value (step S12 in FIG. 2). As described above, the slave node A 22 to which the node identifier is set enters a normal state, and normal communication is started on the communication bus 11.

  Needless to say, the request message and the response message may be transmitted a plurality of times in order to prevent the master node and the slave node from leaking. In addition, the request message and the response message are formed with a configuration different from that of a normal communication message flowing on the communication bus 11. By forming in this way, it is possible to easily distinguish from other communication messages flowing on the communication bus 11. This prevents an erroneous communication message from being used for setting the node identifier.

  Next, the master node 21 receives the response message transmitted from the slave node A22 from the communication bus 11 (step S13 in FIG. 2). Next, the master node 21 determines whether or not a setting start signal has been input by determining whether or not the input value of the digital input 31 has been logically inverted from the slave node C24 previously connected on the notification line 12. to decide. Thus, it is possible to determine whether or not the node identifier setting has been completed for all the slave nodes A22, B23, and C24 (step S14 in FIG. 2). When the master node 21 determines that the input value of the digital input 31 is not changed, that is, determines that the setting start signal is not input (NO), another request message is transmitted on the communication bus 11 ( Step S15 in FIG. Next, it returns to step S12 and repeats the operation | movement shown above.

  Then, by detecting that the input value of the digital input 35 is logically inverted, the slave node B23 performs the same operation as the slave node A22 described above, sets the node identifier of the slave node, and sends a response message. Simultaneously with the transmission on the communication bus 11, the slave node B23 outputs a setting start signal by logically inverting the output value of the digital output 36 from the current value. As described above, the slave node B 23 to which the node identifier is set enters a normal state and starts normal communication on the communication bus 11.

  Then, returning to step S12 again, by detecting that the input value of the digital input 37 has been theoretically inverted, the slave node C24 performs the same operation as the slave nodes A22 and B23 described above, and the slave node C24 The slave node C24 outputs a setting start signal by setting the node identifier and transmitting the response message on the communication bus 11 and simultaneously outputting the output value of the digital output 38 by logically inverting the current value. As described above, the slave node C24 to which the node identifier is set enters a normal state and starts normal communication on the communication bus 11.

  Next, the master node 21 receives the response message transmitted from the slave node C24 (step S13 in FIG. 2). Next, the master node 21 determines that the setting start signal has been input by determining that the input value of the digital input 31 is logically inverted from the slave node C24 previously connected in the notification line 12 (YES), It is determined that node identifiers have been set for all slave nodes A22, B23, and C24, and the setting of node identifiers is terminated.

  In this way, unique node identifiers can be assigned to all the slave nodes A22, B23, and C24 in the network shown in FIG. For convenience, three slave nodes have been described as an example here, but the present invention is not limited to this, and it goes without saying that the same can be done even if one or more slave nodes are provided.

  Next, in the case where the master node 21 cannot receive the response message from any of the slave nodes A22, B23, C24 even after the first predetermined period has elapsed, the node identifier of the communication system shown in FIG. A description will be given based on a flowchart showing the operation of the master node in the setting method. First, the master node 21 outputs a setting start signal from the digital output 32 and transmits a request message onto the communication bus 11 (the same operation as step S21 in FIG. 3 and step S11 shown in FIG. 2). Next, it is determined whether or not a response message has been received from any of the slave nodes A22, B23, and C24 (step S22 in FIG. 3). Thus, it can be determined whether or not there is a response to the request message.

  Next, when it is determined that there is no response to the request message (NO), it is determined whether or not a first predetermined period set in advance has elapsed since the request message was transmitted (step S23 in FIG. 3). . Next, if the first predetermined period has not elapsed (NO), the process returns to step S22 again, and the same operation as the above operation is performed, so that one of the slave nodes A22, B23, C24 Wait for a response message to be sent. Note that the first predetermined period set here is a period longer than the maximum period from when the slave node receives the request message until it transmits the response message, and it does not take any longer. It is set in a period shorter than the period considered to be.

  Next, when it is determined in step S23 that the first predetermined period has elapsed (YES), some kind of communication abnormality has occurred, and the node identifier is normally set to any of the slave nodes A22, B23, C24. Can judge what could not be done. Then, a counter value indicating the number of times the node identifier is set is input from step S26, which will be described later, and the number of slave nodes from which the response message has not been transmitted is recorded (step S24 in FIG. 3). Next, the process returns to step S21 again, and the same operation as the operation described above is repeated.

  Next, when it is determined in step S22 that there is a response to the request message (YES), the master node 21 has received a setting start signal from the slave node C24 previously connected on the notification line 12. (Same operation as step S25 in FIG. 3 and step S14 in FIG. 2). When the master node 21 determines that the input value of the digital input 31 is not changed, that is, determines that the setting start signal is not input (NO), the master node 21 increments the setting number counter value of the node identifier (that is, +1) (step S26 in FIG. 3). Next, another request message is transmitted on the communication bus 11 (the same operation as step S27 in FIG. 3 and step S15 in FIG. 2), the process returns to step S22, and the operation described above is repeated. Further, in step S25, when the master node 21 determines that the setting start signal is input from the slave node C24 previously connected in the notification line 12, it is assumed that node identifiers are set for all the slave nodes A22, B23, and C24. The node identifier setting is completed.

  In this way, in the network shown in FIG. 1, if the response message from any of the slave nodes A22, B23, C24 is not transmitted even after the first predetermined period, the node identifier setting is started again. At the same time, it is possible to record which slave node does not respond.

  Next, when any of the slave nodes A22, B23, C24 is not registered with the node identifier of its own slave node, the node identifier setting is not performed even after the second predetermined period has elapsed. A description will be given based on the flowchart showing the operation of the slave node in the node identifier setting method of the communication system shown above. This process is executed independently by each of the slave nodes A22, B23, C24. First, each of the slave nodes A22, B23, and C24 determines whether or not to receive a request message from the master node 21 depending on whether or not a setting start signal is input from the digital inputs 33, 35, and 37 (FIG. 4). Step S31).

  Next, if it is determined that the setting start signal has not been input (NO), it is determined whether or not a second predetermined period set in advance has elapsed (step S32 in FIG. 4). Next, if the second predetermined period has not elapsed, the process returns to step S31 again to repeat the operation described above to wait for the node identifier setting. Note that the second predetermined period set here is a period longer than the maximum period from when the master node starts setting the node identifier to when a unique node identifier can be assigned to all slave nodes. In addition, it is set in a period shorter than a period in which it will not take any longer.

  Next, when it is determined in step S32 that the second predetermined period has elapsed (YES), a start request message for setting a node identifier is transmitted on the communication bus 11 (step in FIG. 4). S33). Next, the slave node records that the node identifier has not been set even after the second predetermined period has elapsed (step S34 in FIG. 4). Next, the master node 21 receives the start request message from the communication bus 11 and starts the node identifier setting shown in FIG. 2 when the node identifier setting has not started yet. Next, in step S31, when the slave node detects that the setting start signal has been input (YES), the slave node receives a request message from the communication bus 11. Then, the node identifier requested by the request message is set as the node identifier of the own slave node. Then, a response message indicating that the node identifier has been set is transmitted onto the communication bus 11. Then, a setting start signal is output (the same operation as step S35 in FIG. 4 and step S12 in FIG. 2).

  In this way, when the node identifier of the slave node is not registered even after the second predetermined period has elapsed, the start request message can be transmitted to request the master node to start setting the node identifier. it can.

  According to Embodiment 1 of the present invention performed as described above, one master node and one or a plurality of slave nodes are connected by a common communication bus, and the master node and each slave node are node identifiers. In the node identifier setting method of a communication system that is daisy chain connected by a notification line for notifying the setting status and connected in a ring shape, the master node uses the notification line and all the slave nodes have completed the node identifier setting. By determining this, even when the number of slave nodes connected to the network changes, a unique node identifier can be assigned to all slave nodes without changing the data of the master node.

Further, by specifying the slave node that receives the request message transmitted by the master node to only one node using the notification line, the node identifier setting processing of other slave nodes does not collide, so that the node identifier The setting can be completed in a desired period.
Furthermore, by making the request message and the response message different from normal communication messages, it is possible to prevent other messages flowing on the communication bus from being erroneously used for node identifier setting.

Further, when the master node cannot receive the response message from the slave node even after the first predetermined period has elapsed, the master node can start setting the node identifier again.
Furthermore, the master node records the number of the slave node that has not received a response message, thereby making it easy to identify a location where an abnormality has occurred in the network.
In addition, when the node identifier of the slave node is not registered and the node identifier is not set even after the second predetermined period has elapsed, the slave node transmits a start request message on the communication bus. When the master node that has received the node identifier setting starts, a unique node identifier can be reliably assigned to all the slave nodes.
Furthermore, by recording that the node identifier has not been set, the slave node can easily identify the location where an abnormality has occurred in the network.

Embodiment 2. FIG.
FIG. 5 is a flowchart showing a node identifier setting method of the communication system according to Embodiment 2 of the present invention. The configuration of the communication system is the same as that of the first embodiment, and will be described with reference to FIG.

  First, when the communication system is initialized by turning on or resetting the power, the node identifier setting is started. At this time, usually, when a unique node identifier is already recorded in one or more slave nodes, the slave node starts normal communication simultaneously with power-on (hereinafter referred to as a normal state). Next, the master node 21 transmits a preparation start message on the communication bus 11 (step S41 in FIG. 5). Next, when each of the slave nodes A22, B23, and C24 receives a preparation start message from the communication bus 11, transmission of a normal communication message is stopped, and a preparation state for setting a node identifier is entered (step S42 in FIG. 5). .

  Next, similarly to the first embodiment, the same processes as in steps S11 to S15 are performed, and unique node identifiers are assigned to all the slave nodes A22, B23, and C24. However, in the present embodiment, unlike the first embodiment, each of the slave nodes A22, B23, and C24 does not return to the normal state even if the node identifier is set, and stops transmitting the normal communication message. Leave. Next, the master node 21 transmits a node identifier setting completion message onto the communication bus 11 (step S48 in FIG. 5). Next, when each of the slave nodes A22, B23, C24 receives the completion message, the slave node A22, B23, C24 enters a normal state and starts transmitting a normal communication message (step S49 in FIG. 5).

  According to the second embodiment of the present invention performed as described above, the master node transmits the preparation start message and receives all of the same effects as the first embodiment. After the slave node stops sending normal communication messages, node identifier setting is performed, and when the node identifier setting is completed, the master node sends a completion message so that each slave node returns to the normal state. Until all node identifier settings are completed, only the messages used for node identifier setting flow on the communication bus, so that each slave node will not use the wrong message for node identifier setting and is unique to all slave nodes. Node identifiers can be reliably assigned.

  In the second embodiment, an example is shown in which each master node is returned to a normal state after the master node has transmitted a completion message. However, the present invention is not limited to this, and the slave node in which the node identifier is set. May be set to enter a normal state and start normal communication on the communication bus. Even in this case, since the normal state is not obtained until the node identifier is set, the same effect as in the first embodiment can be obtained.

Embodiment 3 FIG.
FIG. 6 is a flowchart showing a node identifier setting method of the communication system according to Embodiment 3 of the present invention. The configuration of the communication system is the same as that of each of the above embodiments, and will be described with reference to FIG. First, when the communication system is initialized by turning on or resetting the power, the node identifier setting is started. At this time, normally, when a unique node identifier is already recorded in one or a plurality of slave nodes, the slave node starts normal communication simultaneously with power-on. Next, the master node 21 outputs the setting start signal from the notification line 12 by logically inverting the output value of the digital output 32 from the current value (step S51 in FIG. 6).

  Next, by detecting that the input value of the digital input 33 is logically inverted, the slave node A22 that has input the setting start signal from the notification line 12 stops the normal communication message and simultaneously outputs the output value of the digital output 34. Is logically inverted from the current value and output, the slave node A22 outputs a setting start signal from the notification line 12. Then, a node identifier setting preparation state is set (step S52 in FIG. 6). Next, the master node 21 determines whether or not a setting start signal has been input by determining whether or not the input value of the digital input 31 has been logically inverted from the slave node C24 previously connected on the notification line 12. to decide. From this, it can be determined whether or not all the slave nodes A22, B23, and C24 are ready for node identifier setting (step S53 in FIG. 6).

  Next, the master node 21 determines that there is no change in the input value of the digital input 31, that is, the setting start signal is not input, and all the slave nodes A22, B23, C24 are ready for node identifier setting. If it is determined that it is not (NO), the process returns to step S52 again, the above-described operation is repeated, and it waits until all the slave nodes are ready for node identifier setting. Then, by detecting that the input value of the digital input 35 is logically inverted, the slave node B23 detects that the setting start signal is input from the notification line 12. Then, the slave node B23 stops the normal communication message and at the same time outputs the output value of the digital output 36 logically inverted from the current value and outputs it as a setting start signal. Then, a node identifier setting preparation state is set (step S52 in FIG. 6).

  Then, by detecting that the input value of the digital input 37 is logically inverted, the slave node C24 detects that the setting start signal has been input. Then, the slave node C24 stops the normal communication message and at the same time outputs the output value of the digital output 38 logically inverted from the current value and outputs it as a setting start signal. Then, a node identifier setting preparation state is set (step S52 in FIG. 6).

  Next, the master node 21 detects that the input value of the digital input 31 has been logically inverted from the previously connected slave node C24 on the notification line 12, that is, determines that a setting start signal has been input, and all slaves It is determined that the nodes A22, B23, and C24 are ready for node identifier setting (YES).

  Next, as in the above embodiments, the master node 21 outputs a setting start signal. Then, the master node 21 transmits a request message onto the communication bus 11 (step S11 in FIG. 6). Next, when the slave node A22 detects that the setting start signal has been input by detecting that the input value of the digital input 33 is logically inverted, the slave node A22 receives a request message from the communication bus 11. Then, the requested node identifier is set as the node identifier of the own slave node A22. Then, a response message indicating that the node identifier has been set is transmitted onto the communication bus 11. Then, the output value of the digital output 34 is logically inverted from the current value and output as a setting start signal (step S12 in FIG. 2).

  Then, the slave node A22 enters a normal state and starts normal communication. Here, since the other slave nodes B23 and C24 in the node identifier setting ready state are not transmitting any message on the communication bus 11, the response message transmitted by the slave node A22 includes a special message. A message configuration used for normal communication may be used instead of a message having a simple configuration. Next, step S13 to step S15 are performed in the same manner as in the above embodiments, and are repeated, so that a unique node identifier is surely assigned to all slave nodes in the network.

  According to the third embodiment of the present invention performed as described above, the response message transmitted by the slave node is shared with the normal communication message as well as the same effects as the above-described embodiments. By doing so, there is no need for the slave node to have a message that is used only for setting the node identifier, and there is an effect that the software configuration becomes easier.

  In each of the above embodiments, a digital input / output line is used as a node identifier setting state notification line configured as a daisy chain connection. Of course, the next node such as an analog input / output line or a serial communication line is used. Any device can be used as long as it can transmit a setting start signal.

It is a figure which shows the structure of the communication system of Embodiment 1 of this invention. It is a flowchart which shows the node identifier setting method in the communication system shown in FIG. 3 is a flowchart showing a node identifier setting process executed by a master node in the communication system shown in FIG. FIG. 3 is a flowchart showing a node identifier setting process executed by a slave node in the communication system shown in FIG. 2. FIG. It is a flowchart which shows the node identifier setting method of the communication system in Embodiment 2 of this invention. It is a flowchart which shows the node identifier setting method of the communication system in Embodiment 3 of this invention.

Explanation of symbols

1 communication bus, 12 notification line, 21 master node, 22 slave node A,
23 Slave node B, 24 Slave node C.

Claims (6)

A master node and one or more slave nodes are connected by a communication bus, and the master node and the one or more slave nodes are daisy chained by a notification line for notifying a node identifier setting status. A node identifier setting method of a communication system that is connected and connected in a ring shape,
The master node outputs a setting start signal to a slave node connected later on the notification line, and the slave node that has input the setting start signal from the notification line stops message transmission on the communication bus. A setting start signal is output to a slave node or a master node connected later on the notification line, and the master node receives the setting start signal from a slave node connected earlier on the notification line. again, the first step of transmitting output again setting start signal to the connected slave node after the above notification line, a request message for setting the node identifier to the slave node on said communication bus,
The slave node receiving the setting start signal from the notification line receives the request message flowing on the communication bus, and sets the node identifier requested by the request message as a unique node identifier of the own slave node. A second step of transmitting a response message indicating that the node identifier has been set on the communication bus, and outputting the setting start signal to a slave node or a master node connected later on the notification line;
If the master node receives the response message and does not receive the setting start signal from a slave node previously connected on the notification line, it sends another request message on the communication bus. Return to the second step,
A third step of ending the node identifier setting when the master node receives the response message and receives the setting start signal from a slave node previously connected in the notification line;
A node identifier setting method for a communication system, comprising: In the third step, before the master node receives the setting start signal from the slave node previously connected on the notification line and ends the node identifier setting, a node identifier setting completion message is sent on the communication bus. The node identifier setting method of the communication system according to claim 1, wherein transmission is performed. 3. The node identifier setting of the communication system according to claim 1, wherein the master node returns to the first step if the response message is not received even after a first predetermined period has elapsed. 4. Method. The master node records which of the slave nodes has not received a response message if the master node has not received the response message even after the first predetermined period has elapsed. node identifier setting method of a communication system according to any one of 3. The slave node transmits a start request message for setting a node identifier on the communication bus if registration is not performed even after the second predetermined period of time has elapsed for the node identifier of the slave node.
The master node receives the start request message, the node identifier setting method of a communication system according to any one of claims 1 to 4, characterized in that to initiate the first step. The slave node records that the node identifier is not set if the node identifier of the slave node is not registered even after the second predetermined period has elapsed. The node identifier setting method of the communication system according to any one of claims 5 .

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