JP2017092856A - Communication equipment and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of a situation where data transmitted from an abnormal slave node may be used by a slave node.SOLUTION: In a communication system 1, a node 2 functions as a master node 2 which transmits a clock signal for causing nodes 2, 3, 4, 5 to synchronize with each other to a communication bus 6. In the communication system 1, the nodes 2, 3, 4, 5 are communicatively connected via the communication bus 6, and the nodes 2, 3, 4, 5 respectively transmit a header for designating the node which should transmit a response, and the node designated by the header transmits a response after the header is transmitted. Then, the node 2 determines whether or not abnormality has occurred in the slave nodes 3, 4, 5. Also, the node 2 prevents an abnormal slave node in which abnormality is determined to have occurred from transmitting a response to the communication bus 6.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication apparatus and a communication system that perform communication by a master-slave method.

  As described in Patent Document 1, in a communication system in which a plurality of communication devices are connected so as to be able to perform data communication, master-slave communication is performed using one communication device as a master node and another communication device as a slave node. Is known to perform.

JP 2007-312043 A

  When an abnormality occurs in a slave node, it is difficult to stop the slave node where the abnormality has occurred (hereinafter referred to as an abnormal slave node), and a normal slave node cannot identify the abnormal slave node. . For this reason, a normal slave node may use data with low reliability transmitted by an abnormal slave node.

  The present invention has been made in view of these problems, and an object thereof is to suppress the occurrence of a situation where a slave node uses data transmitted by an abnormal slave node.

  The first invention made to achieve the above object is to transmit a clock signal for synchronizing a plurality of communication devices (2, 3, 4, 5) to the communication line (6) in the communication system (1). It is a communication apparatus (2) which functions as a master communication apparatus. In the communication system, a plurality of communication devices are connected so as to be able to perform data communication via communication lines, and the plurality of communication devices transmit a header that specifies a communication device to be transmitted, and after the header is transmitted, A system in which a designated communication device transmits a response.

And the communication apparatus (2) of 1st invention is provided with an abnormality determination part (S10-S100) and a disturbance part (S210-S260, S510, S520, S610).
The abnormality determination unit determines whether a communication apparatus other than the master communication apparatus is a slave apparatus among a plurality of communication apparatuses constituting the communication system, and an abnormality has occurred in the slave apparatus.

The interfering unit prevents the abnormal slave device from transmitting a response to the communication line, with the slave device determined by the abnormality determining unit as having an abnormality as the abnormal slave device.
The communication device of the first invention configured as described above prevents the slave device from using the data transmitted by the abnormal slave device in order to prevent the abnormal slave device from transmitting a response to the communication line. Can be suppressed.

  Further, in the second invention, a plurality of communication devices are connected so as to be capable of data communication via a communication line, and the plurality of communication devices transmit a header designating a communication device to be transmitted, and after the header is transmitted, This is a communication system in which a communication device specified by a header transmits a response.

  In the communication system according to the second aspect of the present invention, one communication device that functions as a master communication device that transmits a clock signal for synchronizing the plurality of communication devices to the communication line among the plurality of communication devices includes an abnormality determination unit. And a disturbing part.

  The thus configured communication system of the second invention includes the communication device of the first invention, and can obtain the same effects as the communication device of the first invention.

1 is a block diagram showing a configuration of a communication system 1. FIG. It is explanatory drawing which shows the structure of the transmission-line code | cord | chord used with a communication bus. It is explanatory drawing which shows the structure of the flame | frame transmitted / received via a bus | bath. It is explanatory drawing which shows the content and size of each information which comprise a flame | frame. 3 is a timing chart showing the operation of nodes 2, 3, and 4 of the first embodiment at normal time. It is a flowchart which shows an abnormality detection process. It is a flowchart which shows a clock stop process. It is a flowchart which shows the header transmission process of 1st Embodiment. It is a figure which shows the structure of schedule table ST of 1st Embodiment. It is a timing chart which shows operation | movement of the nodes 2, 3, and 4 of 1st Embodiment at the time of abnormality. It is a timing chart which shows operation | movement of the master node and abnormal slave node of 1st Embodiment at the time of abnormality. It is a figure which shows the structure of schedule table ST of 2nd Embodiment. It is a flowchart which shows a table setting process. It is a flowchart which shows the header transmission process of 2nd Embodiment. It is a timing chart which shows operation of nodes 2, 3, and 4 of a 2nd embodiment at the time of abnormality. It is a timing chart which shows the operation of the master node and abnormal slave node of other embodiments at the time of abnormality.

[First Embodiment]
A first embodiment of the present invention will be described below with reference to the drawings.
A communication system 1 according to the present embodiment is mounted on a vehicle, and includes nodes 2, 3, 4, and 5 as communication devices, as shown in FIG. The nodes 2, 3, 4, and 5 are connected to each other via a communication bus 6 so that data communication is possible.

  The nodes 2, 3, 4, and 5 are mainly configured by a known microcomputer including a CPU, a ROM, a RAM, an I / O, a bus line that connects these components, and the like. Various functions of the microcomputer are realized by the CPU executing a program stored in a non-transitional physical recording medium. In this example, the ROM corresponds to a non-transitional tangible recording medium that stores a program. Further, by executing this program, a method corresponding to the program is executed.

  Of the nodes 2, 3, 4, and 5, the node 2 functions as a master, and the nodes 3, 4, and 5 function as slaves. Hereinafter, the node 2 is also referred to as a master node 2. Nodes 3, 4, and 5 are also referred to as slave nodes 3, 4, and 5, respectively.

  The communication bus 6 is configured such that when a high level signal and a low level signal are simultaneously output from two different nodes, the signal level on the communication bus 6 becomes a low level. Hereinafter, the high level is simply referred to as high and the low level is simply referred to as low.

  As shown in FIG. 2, as a transmission line code “0” or “1” flowing through the communication bus 6, a PWM code whose signal level changes from low to high in the middle of a bit is used. PWM is an abbreviation for Pulse Width Modulation. In this transmission line code, a binary signal that is in a dominant or recessive state is expressed by two types of duty ratios. In the present embodiment, dominant corresponds to “0” and recessive corresponds to “1”.

  Specifically, the dominant ratio is set to be larger than the recessive ratio. In this embodiment, the dominant is set to 2/3 period of 1 bit and the recessive is set to 1/3 period of 1 bit. When a dominant and recessive collision occurs on the communication bus 6, the dominant wins.

As shown in FIG. 3, the communication frame used for communication by the nodes 2, 3, 4 and 5 is composed of a header and a response.
The header stores an “ID” of data permitted to be transmitted. “ID” is also an identifier indicating the type of frame, as shown in FIG. For example, out of the 8 bits forming the header, 7 bits are used as an identifier, and the remaining 1 bit is used as a parity bit.

  As shown in FIGS. 3 and 4, the response includes, in addition to “DATA” that is data specified by the header, 4-bit “DLC”, 2-bit “NM”, and 2-bit “CT”. , And 8-bit “CRC”. Note that “DATA” is variable in the range of 0 to 12 bytes.

“DLC” is information indicating the data length of “DATA” included in the response.
“NM” is information for network management, and includes wake-up pulse transmission information and sleep availability information. The wakeup pulse transmission information is information indicating whether or not a wakeup pulse described later has been transmitted. The wake-up pulse transmission information is set to “1” when the node that has transmitted the communication frame including the wake-up pulse transmission information transmits a wake-up pulse, and “0” when the node does not transmit the wake-up pulse. "Is set. Hereinafter, the wake-up pulse transmission information is referred to as WU pulse transmission information.

  The sleep availability information is information indicating whether or not it is possible to shift to a sleep mode described later. The sleep propriety information is set to “1” when sleep is permitted in the node that has transmitted the communication frame including the sleep propriety information, and is set to “0” when sleep is prohibited.

  “CT” is counter information indicating the continuity of frames. Regarding the response to a specific header, the value of “CT” is updated according to a predetermined rule every time a response to the header is transmitted. For example, if “DATA” in a response to a certain header is important data, and data omission occurs on the receiving side, it is data that greatly affects the control to be performed. Updates the value of “CT” such that “0 → 1 → 2 → 3 → 0” at each transmission. This is because the data receiving side can be detected on the side of receiving the response based on the value of “CT”.

“CRC” is a CRC code for checking a frame error. CRC is an abbreviation for Cyclic Redundancy Check.
Note that since the data to be transmitted by the nodes 2, 3, 4, and 5 is determined in advance, the header is also information for designating a node to which a response is to be transmitted.

  Nodes 2 to 5 operate using the battery voltage of the vehicle as a power source. The operation modes of the nodes 2 to 5 include a wake-up mode and a sleep mode. The wake-up mode is a normal operation mode that can execute all functions assigned in advance. The sleep mode is an operation mode in which some functions are stopped in order to reduce power consumption. The nodes 2 to 5 do not transmit a signal to the communication bus 6 in the sleep mode. When all the nodes 2 to 5 enter the sleep mode, the entire communication system 1 enters the sleep state.

  When the nodes 2 to 5 are in the sleep mode and a wakeup factor determined by themselves occurs, the nodes 2 to 5 wake up. That is, the sleep mode transits to the wake-up mode. Then, the slave nodes 3 to 5 that wake up due to the occurrence of the wake-up factor transmit a wake-up pulse to the communication bus 6. The nodes 2 to 5 wake up by receiving the wake-up pulse. The master node 2 transmits a clock signal to be described later when a wake-up factor is generated.

In the wake-up mode, the master node 2 transitions to the sleep mode and does not transmit a signal to the communication bus 6 when a predetermined condition is satisfied.
In the sleep mode, when the master node 2 wakes up by its own wakeup factor or a wakeup pulse from the slave nodes 3 to 5, when the first specified time elapses from the wakeup time, the master node 2 The transmission of the clock signal to 6 is started. In the present embodiment, the clock signal is a falling edge (that is, an edge serving as a bit boundary) of the transmission line code shown in FIG. When the master node 2 transmits only the clock signal without transmitting the information signal to the communication bus 6, the master node 2 repeatedly transmits the recessive signal shown in FIG.

  Then, the master node 2 starts transmitting a header to the communication bus 6 when a second specified time longer than the first specified time elapses from the wake-up time. There are a plurality of types of headers transmitted from the master node 2, and each header is periodically transmitted according to a predetermined schedule. When the master node 2 is transmitting a header, the falling edge as the boundary of each bit in the transmitted header is handled as a clock signal in the slave nodes 3 to 5. That is, the master node 2 transmits both the clock signal and the header information to the communication bus 6.

  The slave nodes 3 to 5 also transition to the sleep mode when a predetermined condition is satisfied. For example, the slave nodes 3 to 5 transition to the sleep mode when a sleep frame instructing transition to the sleep mode is received or when a continuous time during which no header is received is equal to or longer than a predetermined error determination time. The error determination time is sufficiently longer than the second specified time.

  When the slave nodes 3 to 5 wake up due to their own wake-up factor or wake-up pulses from other nodes in the sleep mode, they extract the falling edge of the signal flowing through the communication bus 6 as a clock signal. The communication operation is performed in synchronization with the clock signal.

  When the slave nodes 3 to 5 receive the header specifying itself, the slave nodes 3 to 5 transmit a response to be transmitted to the communication bus 6 to the header. At that time, the slave nodes 3 to 5 perform decoding of received data, encoding of transmission data into a PWM code, and the like at a timing synchronized with the clock signal extracted from the communication bus 6.

  Also, when an event that requires a response to occur occurs, the nodes 2 to 5 can autonomously transmit a response by transmitting a header that specifies the response to the communication bus 6.

  For example, as shown in FIG. 5, when the master node 2 transmits a header HD1 specifying the slave node 4 to the communication bus 6, the slave node 4 transmits a response RP1 to be transmitted to the header HD1 to the communication bus 6. To do. Similarly, when the master node 2 transmits a header HD2 designating the slave node 3 to the communication bus 6, the slave node 3 transmits a response RP2 to be transmitted to the header HD2 to the communication bus 6. Further, when the slave node 4 transmits the header HD3 designating itself to the communication bus 6, the slave node 4 transmits a response RP3 to be transmitted to the header HD3 to the communication bus 6.

  In the communication system 1 configured as described above, the master node 2 executes an abnormality detection process described later, a clock stop process described later, and a header transmission process described later. Note that some or all of the functions executed by the master node 2 may be configured in hardware by one or a plurality of ICs.

First, the procedure of the abnormality detection process will be described. The abnormality detection process is a process that is repeatedly executed during the operation of the master node 2.
When the abnormality detection process is executed, the CPU of the master node 2 first starts a monitoring timer in S10 as shown in FIG. This monitoring timer is a timer that is incremented, for example, every 100 ms, and its value is incremented from 0 when activated. “Increment” means “add 1”.

  In S20, it is determined whether or not the master node 2 is waked up. If the master node 2 has not been woken up, the process proceeds to S80. On the other hand, if the master node 2 has been woken up, it is determined in S30 whether a response has been received from any of the slave nodes 3, 4, and 5. If no response has been received, the process of S30 is repeated to wait until a response is received from any of the slave nodes 3, 4, and 5.

  When a response is received from any of the slave nodes 3, 4, 5, it is determined in S 40 whether or not the WU pulse transmission information of the received response is set to “1”. If the WU pulse transmission information is set to “0”, the process proceeds to S80.

  On the other hand, if the WU pulse transmission information of the response is set to “1”, the wake-up counter provided corresponding to the transmission source of the response received in S30 is incremented in S50. Note that the wake-up counter is provided in the RAM of the master node 2 corresponding to each of the slave nodes 3, 4, and 5. Hereinafter, the wake-up counter is referred to as a WU counter.

  Thereafter, in S60, it is determined whether or not the value of the WU counter provided corresponding to the transmission source of the response received in S30 (hereinafter referred to as the WU count) is equal to or greater than a preset abnormality determination count. In the present embodiment, the abnormality determination count is set to 100, for example.

  If the number of WUs is less than the number of abnormality determinations, the process proceeds to S80. On the other hand, if the number of WUs is equal to or greater than the number of abnormality determinations, in S70, transmission source information indicating the transmission source of the response received in S20 is set in the abnormal slave information provided in the RAM of the master node 2. , The process proceeds to S80.

In S80, it is determined whether or not the + B state continues. The + B state is a state in which the ignition power source and the accessory power source are off.
If the + B state is not continued, the process proceeds to S100. On the other hand, if the + B state continues, it is determined in S90 whether a preset monitoring time has elapsed. Specifically, it is determined whether or not the value of the monitoring timer is greater than or equal to the value corresponding to the monitoring time. In this embodiment, the monitoring time is set to 60 minutes, for example.

  If the monitoring time has not elapsed, the process proceeds to S30. On the other hand, if the monitoring time has elapsed, in S100, the WU counter corresponding to each of the slave nodes 3, 4, and 5 is reset, and the abnormal wakeup detection process is temporarily ended. Note that “reset” means “set to 0”.

Next, the procedure of the clock stop process will be described. The clock stop process is a process that is repeatedly executed during the operation of the master node 2.
When the clock stop process is executed, the CPU of the master node 2 first determines whether or not a header has been received in S210, as shown in FIG. If the header has not been received, the process of S210 is repeated to wait until the header is received. When the header is received, in S220, it is determined whether or not the received header is transmitted by a slave node in which an abnormality has occurred (hereinafter referred to as an abnormal slave node). Specifically, the slave node that transmitted the header is specified based on the “ID” stored in the received header. Since “ID” has a unique value for each slave, it is possible to specify a slave node based on “ID”. Furthermore, when the slave node specified based on “ID” is set in the abnormal slave information, it is determined that the received header is transmitted by the abnormal slave node.

  If it is determined that the header is not transmitted by the abnormal slave node, the clock stop process is temporarily terminated. On the other hand, if it is determined that the header is transmitted by the abnormal slave node, transmission of the clock signal is stopped in S230. In S240, a stop timer is started. This stop timer is, for example, a timer that increments every bit time, and when activated, its value increments from zero. Bit time refers to the time required to transfer one bit. For example, 10-bit time is the time required to transfer 10 bits.

  Next, in S250, it is determined whether a preset stop time has elapsed. Specifically, it is determined whether or not the value of the stop timer is equal to or greater than a value corresponding to the stop time. In this embodiment, the stop time is set to 10 bit time, for example.

  If the stop time has not elapsed, the process of S250 is repeated to wait until the stop time elapses. When the stop time elapses, transmission of a clock signal is started in S260, and the clock stop process is temporarily ended.

Next, the procedure of the header transmission process will be described. The header transmission process is a process repeatedly executed during the operation of the master node 2.
When the header transmission process is executed, the CPU of the master node 2 first increments the transmission order counter in S310 as shown in FIG. Note that the initial value of the transmission order counter is zero.

  In S320, the slave node corresponding to the transmission order indicated by the transmission order counter is specified by referring to a preset schedule table ST as shown in FIG. 9, for example.

  In the schedule table ST of the present embodiment, correspondence relationships among transmission order information, target slave information, and transmission interval information are set. The transmission order information indicates the transmission order of the header. The target slave information indicates a slave node that is a target of header transmission. The transmission interval information indicates the transmission interval of the header.

  The schedule table ST of the present embodiment is set so that the header specifying the slave node 3 is transmitted first. The schedule table ST is set to transmit the header specifying the slave node 4 second after 1000 ms has elapsed. The schedule table ST is set so that the header specifying the slave node 3 is transmitted third after 2000 ms further passes, and the header specifying the slave node 4 is transmitted fourth after 500 ms elapses. Yes. The schedule table ST is set so that the header specifying the slave node 5 is transmitted fifth after 500 ms has passed. The schedule table ST is set to return to the first after a further 1000 ms and transmit a header specifying the slave node 3.

  When the process of S320 ends, as shown in FIG. 8, in S330, a header designating the slave node specified in S320 is transmitted. In S340, the header transmission interval corresponding to the transmission order indicated by the transmission order counter is specified by referring to the schedule table ST.

In S350, the transmission timer is started. This transmission timer is, for example, a timer that increments every 10 ms, and when activated, its value increments from zero.
Next, in S360, it is determined whether the header transmission interval specified in S340 has elapsed. Specifically, it is determined whether or not the value of the transmission timer is equal to or greater than the value corresponding to the header transmission interval specified in S340.

  Here, if the header transmission interval has not elapsed, the process of S360 is repeated to wait until the header transmission interval has elapsed. When the header transmission interval elapses, it is determined in S370 whether or not the transmission order indicated by the transmission order counter is equal to or greater than a preset maximum transmission order. In the present embodiment, since the transmission order of the schedule table ST is set from 1 to 5, the maximum transmission order is 5.

  Here, if the transmission order is less than the maximum transmission order, the header transmission process is temporarily terminated. On the other hand, if the transmission order is greater than or equal to the maximum transmission order, the transmission order counter is reset in S380, and the header transmission process is temporarily terminated.

Next, an operation example of the master node 2 configured as described above will be described.
For example, as shown in FIG. 10, when the slave node 4 that is an abnormal slave node transmits the header HD11, the master node 2 stops the transmission of the clock signal as indicated by the clock stop period Tcs1. Thereby, transmission of response RP11 resulting from header transmission by slave node 4 can be prevented. On the other hand, when the slave node 3 that is not an abnormal slave node transmits the header HD12, as indicated by the clock operation period Tcd1, the master node 2 continues to transmit the clock signal. Thereby, the response RP12 resulting from the header transmission by the slave node 3 is transmitted.

  In FIG. 11, it is assumed that the clock signal is transmitted as indicated by the clock operation period Tcd11, and at this time, the header HD21 is transmitted from the transmission terminal Tx of the abnormal slave node. When the master node 2 receives the header HD21 via the communication bus 6, the master node 2 stops the transmission of the clock signal until the 10-bit time has elapsed as indicated by the clock stop period Tcs11. As a result, even if the abnormal slave node receives the header HD21 via the reception terminal Rx and executes the process of transmitting the response RP21 from the transmission terminal Tx, the response RP21 is not transmitted to the communication bus 6 and is defined. As time passes, an error occurs as indicated by error ER1. The specified time of this embodiment is set to 9 bit time or less.

  When 10-bit time has elapsed since the transmission of the clock signal is stopped, the master node 2 transmits the clock signal as indicated by the clock operation period Tcd12. Then, it is assumed that the header HD22 is transmitted from the transmission terminal Tx of the abnormal slave node after the IFS has elapsed since the header HD21 was transmitted. IFS is an abbreviation for Inter Frame Space, and is set to, for example, 20 bit times in this embodiment.

  When the master node 2 receives the header HD22 via the communication bus 6, the master node 2 stops transmitting the clock signal until the 10-bit time has elapsed, as indicated by the clock stop period Tcs12. As a result, even if the process of transmitting the response RP22 from the transmission terminal Tx of the abnormal slave node is executed, the response RP22 is not transmitted to the communication bus 6, and as the error ER2 indicates that the specified time has elapsed, An error occurs. Thus, even if the header is transmitted again from the transmission terminal Tx of the abnormal slave node, the transmission of the clock signal is stopped. The number of header retransmissions is finite, and transmission of a header from an abnormal slave node is stopped when header transmission is performed for a preset number of retransmissions.

  The node 2 configured as described above functions as the master node 2 that transmits a clock signal for synchronizing the nodes 2, 3, 4, and 5 to the communication bus 6 in the communication system 1. In the communication system 1, the nodes 2, 3, 4, and 5 are connected to be able to perform data communication via the communication bus 6, and the nodes 2, 3, 4, and 5 transmit headers that specify nodes to be transmitted, This is a system in which a node specified by a header transmits a response after the header is transmitted.

  Then, the node 2 determines whether or not an abnormality has occurred in the slave nodes 3, 4, and 5. Further, when the node 2 receives the header, the node 2 determines whether or not the header is transmitted by the abnormal slave node. When the node 2 determines that the header is transmitted by the abnormal slave node, the node 2 stops transmitting the clock signal for a preset stop time, so that the abnormal slave node sends a response to the communication bus 6. Prevent transmission.

  As a result, the node 2 prevents the abnormal slave node from sending a response to the communication bus 6, thereby suppressing occurrence of a situation where the slave nodes 3, 4, and 5 use the data transmitted by the abnormal slave node. can do.

The node 2 can prevent the abnormal slave node from transmitting a response autonomously by transmitting a header designating itself to the communication bus 6.
In the embodiment described above, the nodes 2, 3, 4, and 5 correspond to communication devices, the communication bus 6 corresponds to a communication line, the node 2 corresponds to a master communication device, and the nodes 3, 4, and 5 correspond to slave devices.

Further, the abnormal slave node corresponds to an abnormal slave device, the processes in S10 to S100 correspond to an abnormality determination unit, and the processes in S210 to S260 correspond to an obstruction unit.
[Second Embodiment]
A second embodiment of the present invention will be described below with reference to the drawings. In the second embodiment, parts different from the first embodiment will be described. The same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description is referred to.

  In the communication system 1 of the second embodiment, the clock stop process is omitted, the schedule table ST is changed, the table setting process described later is added, and the header transmission process is changed. Is different from the first embodiment.

  As shown in FIG. 12, the schedule table ST of the second embodiment has a correspondence relationship with transmission permission / inhibition information in addition to transmission order information, target slave information, and transmission interval information. And different. The transmission availability information indicates whether header transmission is possible.

Next, the table setting process will be described. The table setting process is a process that is repeatedly executed during the operation of the master node 2.
When the table setting process is executed, as shown in FIG. 13, the CPU of the master node 2 first identifies the abnormal slave node by referring to the abnormal slave information in S510.

  In S520, transmission permission / prohibition information of the schedule table ST is set based on the abnormal slave node specified in S510. Specifically, when the slave node indicated by the target slave information in the schedule table ST is included in one or more abnormal slave nodes specified in S510, transmission permission / inhibition information corresponding to the target slave information is displayed. Set to “No”. On the other hand, when the slave node indicated by the target slave information in the schedule table ST is not included in the one or more abnormal slave nodes specified in S510, the transmission availability information corresponding to the target slave information is set to “ Set to “Yes”.

When the process of S520 is completed, the table setting process is temporarily ended.
Next, the procedure of the header transmission process of the second embodiment will be described.
As shown in FIG. 14, the header transmission process of the second embodiment is different from the first embodiment in that the process of S610 is added.

  That is, when the process of S320 is completed, it is determined in S610 whether or not a header specifying the slave node specified in S320 can be transmitted. Specifically, referring to the schedule table ST, if the transmission permission / inhibition information corresponding to the transmission order indicated by the transmission order counter is set to “permitted”, it is determined that the header can be transmitted. On the other hand, when the transmission permission / inhibition information is set to “No”, it is determined that the header cannot be transmitted.

If it is determined that the header can be transmitted, the process proceeds to S330. On the other hand, if it is determined that the header cannot be transmitted, the process proceeds to S340.
Next, an operation example of the master node 2 configured as described above will be described.

  For example, as shown in FIG. 15, when it is time to transmit the header HD 31 designating the slave node 4 to the communication bus 6 based on the schedule table ST, the slave node 4 is an abnormal slave node, so the header HD 31 is not transmitted. Thereby, transmission of the response RP31 by the slave node 4 can be prevented. On the other hand, when it is time to transmit the header HD32 designating the slave node 3 to the communication bus 6, since the slave node 3 is not an abnormal slave node, the header HD32 is transmitted. Thereby, the response RP32 is transmitted by the slave node 3.

  The node 2 configured in this way transmits the header based on the schedule table ST in which the correspondence relationship between at least the header transmission order and the slave node specified by the header is preset. The node 2 prevents the abnormal slave node from transmitting a response to the communication bus 6 by changing the schedule table ST so as to prohibit transmission of a header designating the abnormal slave node.

  Thereby, the node 2 of 2nd Embodiment has an effect similar to the node 2 of 1st Embodiment. The node 2 can prevent the abnormal slave node from periodically transmitting a response based on the schedule table ST.

  Further, in the schedule table ST, in addition to the transmission order and slave nodes, a correspondence relationship with transmission availability information indicating whether header transmission is possible is set in advance. Then, the node 2 changes the transmission availability information corresponding to the abnormal slave node to “No” indicating that the header cannot be transmitted.

  Thereby, the node 2 of the second embodiment can determine whether or not to transmit the header by a simple process of referring to the transmission permission / inhibition information. For this reason, the node 2 can reduce the processing load for preventing the abnormal slave node from transmitting a response.

In the embodiment described above, the processing of S310 to S380 corresponds to a header transmission unit, and the processing of S510, S520, and S610 corresponds to an obstruction unit.
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, As long as it belongs to the technical scope of this invention, a various form can be taken.

[Modification 1]
For example, in the above embodiment, the communication system 1 is configured with three slave nodes. However, the communication system 1 may be configured with two or four or more slave nodes.

[Modification 2]
In the above embodiment, as shown in FIG. 11, the signal level of the receiving terminal Rx of the abnormal slave node is high when the transmission of the clock signal is stopped. However, as shown in FIG. 16, even when the signal levels LV1 and LV2 are low when the transmission of the clock signal is stopped, the error can be detected as indicated by the errors ER1 and ER2. it can.

[Modification 3]
Moreover, in the said embodiment, what detected the abnormal slave node based on the WU pulse transmission information of a response was shown. However, the method for detecting an abnormal slave node is not limited to that described in the above embodiment. For example, an abnormal slave node may be detected based on the sleep availability information of the response.

  In addition, the functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claim are embodiment of this invention.

  In addition to the master node 2 described above, the present invention can be implemented in various forms such as a system having the master node 2 as a constituent element, a program for causing a computer to function as the master node 2, a medium on which the program is recorded, and a communication method. It can also be realized.

  DESCRIPTION OF SYMBOLS 1 ... Communication system, 2 ... Master node, 3, 4, 5 ... Slave node, 6 ... Communication bus

Claims (5)

A plurality of communication devices (2, 3, 4, 5) are connected via a communication line (6) so that data communication is possible, and the plurality of communication devices transmit headers that specify the communication devices to be transmitted. In the communication system (1) in which the communication device specified by the header transmits a response after the header is transmitted, a master that transmits a clock signal for synchronizing a plurality of the communication devices to the communication line A communication device (2) functioning as a communication device,
Among the plurality of communication devices constituting the communication system, the communication device other than the master communication device is set as a slave device (3, 4, 5), and it is determined whether or not an abnormality has occurred in the slave device. An abnormality determination unit (S10 to S100);
An obstruction unit (S210 to S260, S510, S510, S510, S510) that prevents the abnormal slave device from transmitting the response to the communication line, using the slave device determined by the abnormality determination unit as an abnormal slave device when an abnormality has occurred. S520, S610). The communication device according to claim 1,
Upon receiving the header, the disturbing unit (S210 to S260) determines whether the header is transmitted by the abnormal slave device, and the header is transmitted by the abnormal slave device. When it is determined that there is a communication device, the transmission of the clock signal is stopped for a preset stop time, thereby preventing the abnormal slave device from transmitting the response to the communication line. The communication device according to claim 1,
A header transmission unit (S310 to S380) for transmitting the header based on at least a schedule table in which a correspondence relationship between the transmission order of the header and the slave device specified by the header is set in advance;
The disturbing unit (S510, S520, S610) changes the schedule table so as to prohibit the header transmitting unit from transmitting the header designating the abnormal slave device. A communication device that prevents transmission of the response to a communication line. The communication device according to claim 3,
In the schedule table, in addition to the transmission order and the slave device, a correspondence relationship with transmission availability information indicating whether transmission of the header is possible is set in advance,
The communication device, wherein the disturbing unit changes the transmission permission information corresponding to the abnormal slave device so as to indicate that the header cannot be transmitted. A plurality of communication devices (2, 3, 4, 5) are connected via a communication line (6) so that data communication is possible, and the plurality of communication devices transmit headers that specify the communication devices to be transmitted. A communication system (1) in which, after the header is transmitted, the communication device specified by the header transmits a response,
Among the plurality of communication devices, one communication device (2) functioning as a master communication device that transmits a clock signal for synchronizing the plurality of communication devices to the communication line,
Among the plurality of communication devices constituting the communication system, the communication device other than the master communication device is set as a slave device (3, 4, 5), and it is determined whether or not an abnormality has occurred in the slave device. An abnormality determination unit (S10 to S100);
Using the slave device determined by the abnormality determination unit as an abnormal slave device as an abnormal slave device, an obstruction unit (S210 to S260, S510, S520, S610).

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