JP4033108B2 - CSMA data communication method and broadcast transmission node device and slave node device using the same method - Google Patents

Description

  The present invention relates to a CSMA data communication method for a bus type system in which a parent device and a plurality of terminals are mutually controlled by the CSMA / ACK method, and a broadcast transmission node device and a child device node device using the method.

  In the transmission system called CSMA / CD (Carrier Sense Multiple Access with Collision Detection), which is commonly used, collision detection of transmission data signals is performed and collision between transmission data signals is detected. In this case, the transmission of the data signal is immediately stopped, and after a random time, a retry transmission is performed. That is, a plurality of terminals (nodes) monitor transmission of a shared line, and when a transmission signal is not confirmed on the line, an arbitrary terminal that desires to transmit transmits a data signal to the line.

  On the other hand, unlike the CSMA / CD system, in the CSMA / ACK transmission system, if the ACK signal from the receiving terminal is received within a predetermined time without detecting the collision of the transmitted data signal, it is considered that the transmission has been established, and the ACK signal If it cannot be received within a predetermined time, it is considered that transmission has failed, and retry transmission is performed. In this bus type transmission system using the CSMA / ACK transmission method, when the communication is one-to-one unicast communication, the transmitting side terminal transmits a data signal to the receiving side terminal, and then the receiving side terminal normally An ACK signal notifying that it has been received is received, and the delivery of the data signal is confirmed by looking at it. If the ACK signal cannot be normally received within a certain time, the transmitting terminal determines that the delivery has failed and retransmits the data signal.

  However, only in the case of a plurality of communication partners such as broadcast communication in the CSMA / ACK transmission system, ACK signals of a plurality of terminals are mixed and collide with each other on the transmission path. do not use. However, an invention for ordering the generation timings of a plurality of ACK signals so that the plurality of ACK signals do not collide on the transmission path during broadcasting is disclosed in, for example, the following patent documents.

FIG. 10 and FIG. 11 explain this prior art. In the system configuration diagram shown in FIG. 10, each of the nodes 10 ₁ , 10 ₂ , 10 ₃ ,... Is connected to the transmission line Ls by bus connection and CSMA / ACK. Access is controlled by the method. In FIG. 10, among the nodes corresponding to the slave units, the case where the unicast packets UP10 ₂ and UP10 ₃ are respectively transmitted at the same unicast transmission timing with the codes 10 ₂ and 10 ₃ is schematically shown. Naturally, the unicast packets UP10 ₂ and UP10 ₃ collide on the transmission line Ls, and thus do not normally reach any node. In the case of communication of the broadcast packet BP, as illustrated in FIG. 11, the period of the transmission prohibition period T_NG for detecting the ACK reply is subdivided, and the ACK reply (for example, ACK10 ₂ , ACK10 ₃ , By setting the timing of ACK 10 ₄ ,...) At a different timing for each reply node, an attempt is made to prevent collision between ACK replies.
Japanese Patent Laid-Open No. 4-6927 Japanese Patent Laid-Open No. 11-112530

  Conventionally, in the case of broadcast communication, if an ACK signal is not used, there is no way to confirm with high probability whether or not transmission can be performed to a transmission destination terminal.

  However, even if an ACK signal is used in the case of broadcast communication based on Patent Documents 1 and 2, as disclosed in Patent Documents 1 and 2, the generation timing of a plurality of ACK signals is negotiated. Therefore, a complicated function for determining the generation timing of the ACK signal is required, which is not preferable.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a CSMA data communication method that can make CSMA broadcasting succeed with high probability without adopting an ACK reply. .

In order to solve the above-described problem, in the CSMA data communication method according to claim 1, a plurality of nodes whose access is controlled by the CSMA / ACK method are bus-connected to a transmission line, and a node desiring to transmit an ACK response Unicast packet transmission is performed only after each start time of the unicast transmission period that is set and divided approximately equal to the time required for carrier sense after the transmission prohibition period to detect In the CSMA / ACK bus type data transmission system, the node determines whether or not the receiving node has received the data based on the presence or absence of an ACK response indicating an affirmative response during the transmission prohibition period. Broadcast packet transmission that does not require an ACK reply until the cast packet transmission period is broadcast The only broadcast transmission period only allows nodes with limited provided, if desired nodes broadcast transmission does not have the broadcast rights, this node is the only node addressed with a broadcast transmission authorization, the broadcast transmission period The broadcast transmission proxy request signal for requesting the broadcast transmission to be delegated and the broadcast content signal, which is a signal indicating the broadcast content, are transmitted at any opportunity during the unicast transmission period, and broadcast transmission authority is granted. The only node that has a unicast signal that combines the broadcast transmission proxy request signal and the broadcast content signal, and that is in a processing state that can accept the broadcast transmission proxy request, is the unicast signal. The received broadcast transmission period of the next opportunity, the broadcast content signal contained in the received said unicast signal, and transmits by broadcast to the bus system.

In the CSMA data communication method according to claim 2, when a node that desires broadcast transmission does not have broadcast transmission authority in claim 1 , this node broadcasts to only one node having broadcast transmission authority. A broadcast transmission permission request signal for applying to allow broadcast transmission in the transmission period is transmitted at any opportunity in the unicast transmission period, and the only node having broadcast transmission authority transmits the broadcast transmission permission request signal. A broadcast that indicates permission for the broadcast transmission permission request signal in the ACK reply that responds in the transmission prohibition period immediately after this unicast signal if the unicast signal is received and the broadcast transmission request is accepted. Cass The node that transmitted the transmission permission signal and transmitted the broadcast transmission permission request signal, when receiving the broadcast transmission permission signal, at least in the broadcast transmission period of the next opportunity that received the broadcast transmission permission signal, Instead of being the only node with broadcast transmission authority, it is characterized by transmitting in the bus system by broadcast .

The CSMA data communication method according to claim 3, wherein a broadcast transmission requesting node that has impersonated a single node having broadcast transmission authority in claim 2 has passed a transmission prohibition period immediately after performing broadcast transmission. The same broadcast signal is sent and this broadcast continuous transmission has been applied to be included in the broadcast transmission permission request signal, or has been specified to be included in the received broadcast transmission permission signal, a predetermined number of times, It is characterized by repetition .

5. The broadcast transmission node device according to claim 4, wherein the broadcast transmission node device is the only node device having a broadcast transmission authority in the CSMA / ACK scheme, and a transmission prohibition period for detecting an ACK reply has elapsed. After that, not only is it configured to enable unicast packet transmission only at each start time of the unicast transmission period set and divided approximately equal to the time required for carrier sense, and further, the transmission prohibited period and The slave node device that is provided between the end of the transmission prohibition period and the next unicast packet transmission period and is connected in the same bus system and controlled for access by the CSMA / ACK method is prohibited from transmission. Enables transmission of broadcast packets that do not require ACK replies during the broadcast transmission period Thus, the broadcast transmission node device may accept the broadcast transmission proxy request when receiving a unicast signal that combines the broadcast transmission proxy request signal and the broadcast content signal at any opportunity during the unicast transmission period. If in the processing state, the broadcast content signal included in the received unicast signal is broadcast and transmitted in the bus system in the broadcast transmission period of the next opportunity of receiving this unicast signal. And

The slave node device according to claim 5, wherein the slave node device is access-controlled by the CSMA / ACK method, and if transmission is desired, a transmission prohibition period for detecting an ACK reply has elapsed. Thereafter, unicast packet transmission is performed only at each start time of the unicast transmission period set and divided approximately equal to the time required for carrier sense, and the transmission prohibition period and the transmission prohibition period include Broadcast transmission period that is provided between the end of the transmission and the next unicast packet transmission period, and that can be transmitted only by the only broadcast transmission node device that is connected in the bus system and is access-controlled by the CSMA / ACK method. Is prohibited from transmission, and when the slave node device desires broadcast transmission, A unicast transmission period that combines a broadcast transmission proxy request signal for requesting that the broadcast transmission in the broadcast transmission period be delegated to the loadcast transmission node device, and a broadcast content signal that represents the content of the broadcast. It is characterized by transmitting on any occasion of .

The broadcast transmission node device according to claim 6, wherein the broadcast transmission node device requests to permit broadcast transmission in the broadcast transmission period at any opportunity in the unicast transmission period. If the broadcast transmission permission request signal indicating that the broadcast transmission request is accepted is in a processing state in which the broadcast transmission request can be accepted, an ACK response responding in the transmission prohibition period immediately after the unicast signal is sent to the broadcast transmission permission request signal. A broadcast transmission permission signal that indicates permission is transmitted, and broadcast transmission is not performed at least in the broadcast transmission period of the next opportunity after receiving the broadcast transmission permission signal .

The slave node device according to claim 7, wherein the slave node device permits broadcast transmission in a broadcast transmission period to the broadcast transmission node device when requesting broadcast transmission in claim 5. Broadcast transmission permission request signal to apply to be transmitted at any opportunity in the unicast transmission period, in the ACK reply received from the broadcast transmission node device in the transmission prohibition period immediately after this unicast signal, When a broadcast transmission permission signal indicating permission for the broadcast transmission permission request signal is received and received, at least in the broadcast transmission period of the next opportunity after receiving the broadcast transmission permission signal, it replaces the broadcast transmission node device, and the bus Characterized in that it broadcasts to the stem.

The slave node device according to claim 8 is the slave node device according to claim 7, wherein the slave node device transmits the same broadcast signal after a transmission prohibition period immediately after performing broadcast transmission. The transmission is repeated a predetermined number of times that has been applied for in the broadcast transmission permission request signal or specified in the received broadcast transmission permission signal .

  As described above, since a broadcast transmission period in which only a node having broadcast transmission authority can perform broadcast transmission that does not require ACK reply is provided immediately after the transmission prohibition period elapses until the next unicast transmission period. Since it is the only node that has permission to send and broadcast packets can be delivered with priority over any unicast communication, broadcast packets cannot collide with each other, It becomes easy to deliver the broadcast packet to each node. In addition, since it is not necessary to use an ACK reply at the time of broadcasting, it is not necessary to complicate the communication function of each node in order to avoid a collision between a plurality of ACK replies as in the prior art.

  Hereinafter, an embodiment of a bus type transmission system employing a CSMA / ACK transmission system according to the present invention will be described with reference to FIGS.

  In any case, a terminal (slave unit) in a receiving state among a plurality of nodes returns an ACK signal to a transmitting side terminal (slave unit or base unit in a transmission right holding state). Only if done. That is, the ACK signal is not returned in the case of broadcast communication or when the receiving terminal cannot normally receive the data signal even in unicast communication. In addition, it is assumed that a preset fixed address such as 0xFF is used as a destination when performing broadcast communication, and 0x01 or the like is also used when communicating with a parent device corresponding to a single node having broadcast transmission authority. It is assumed that a fixed address set in advance is used.

(First embodiment)
This will be described with reference to FIGS. FIG. 1 is a system configuration diagram, and FIGS. 2 to 6 are time charts showing the generation timing of unicast and broadcast packets and ACK replies flowing through the transmission line Ls.

As shown in FIG. 1, each of the nodes 10 ₁ , 10 ₂ , 10 ₃ ,... Is bus-connected to the transmission line Ls and is access controlled by the CSMA / ACK method. Node 10 ₁ corresponds to the master unit of this bus type transmission system, the other node _{10 2, 10 3, ...,} 10 x, ..., 10 n corresponds to the child device of the bus type transmission system. The situation in FIG. 1 in which the base unit node 10 ₁ and the slave device node 10 _x is a packet transmitted at the same timing schematizes.

As shown in FIG. 2, the node _{10 1, 10 2, 10 3} , ..., 10 x, ..., one of the nodes 10 _k of 10 _n is assumed that sent unicast packets UP10 _k. Then, the node 10 _k is, only the transmission inhibition period T_NG after unicast packets UP10 _k finished, by detecting the acknowledgment reply ACK from the packet UP10 _k responding node specified in the destination address of 10 _t, Uni The communication starting from the cast packet UP10 _k is terminated.

The details are as follows. The node 10 _k desiring to transmit first performs carrier sense, and immediately sends out a unicast packet UP10 _k to be transmitted when other nodes are not communicating. If another node is already communicating, it waits until the communication is completed including the transmission packet or ACK reply. If desired transmission node 10 _k could sending a unicast packet UP10 _k, beginning balance from the time T1 which has finished sending the unicast packet UP10 _k, only the transmission prohibition period T_NG, all transmissions except ACK returned is prohibited ing. The transmission prohibition period T_NG is set at different time intervals depending on whether or not an ACK is returned. The ACK return has a time regulation in which the ACK can be returned, and the transmission of the ACK signal when the ACK return timeout time TO is exceeded is prohibited. When there is an ACK return, a period in which the interframe gap time IFG, which is the minimum gap time between consecutive packets, is further added to the time points T1 to T2, starting from the end timing T2 of the ACK signal, is the transmission prohibited period. T_NG. When no ACK is returned, the transmission prohibition period T_NG is equal to the interframe gap time IFG. However, ACK return timeout time TO <interframe gap time IFG.

When the transmission prohibition period T_NG ends, a broadcast transmission period BT in which transmission of only broadcast packets by the parent node 10 ₁ is permitted, and a plurality of unicast transmission periods UT ₁ , UT in which transmission of only unicast packets is permitted. ₂ , ..., UT _n follows. The time interval between the broadcast transmission period BT and the respective unicast transmission periods UT ₁ , UT ₂ ,... UT _n is set longer than the time required for each node to perform carrier sense. The broadcast packet is always sent out at the start of the only broadcast transmission period BT, but the next unicast packet UP10 _t to be generated is any one unicast randomly selected by the desired transmission node UP10 _t. It is sent out at the start of the transmission period (FIG. 2 shows an example of UT ₂ ).

Since the broadcast transmission period BT is prepared in this way, as shown in FIG. 3, when the parent node 10 ₁ performs broadcast transmission, the broadcast originating from the parent node 10 ₁ is broadcast in the broadcast transmission period BT. Packet BP10 ₁ is transmitted. As illustrated in FIG. 3, since the data amount of the broadcast packet BP10 ₁ is variable, if the data amount is large, it may take up to the unicast transmission period UT ₁ immediately after that. If there is no ACK reply as shown in FIG. 3, to be sometimes abnormal communication by ACK reply is not satisfied such that there is no ACK reply to unicast packets UP10 _k immediately before, the broadcast packets instead of unicast packets UP10 _k There is also a possibility that

As shown in FIG. 4, Tatoeko computer node _{10 2, 10 3, ...,} 10 x, ..., any desired transmission node 10 _k of 10 _n unicast packets UP10 the first unicast transmission period UT ₁ even trying to sending a _k, since the broadcast transmission period BT already broadcast packets BP10 ₁ will have been delivered, the desired transmission node 10 _k unicast packets UP10 _k in the first unicast transmission period UT ₁ discontinued for delivering is a 'wait for the opportunity to broadcast packets BP10 ₁ is not transmitted, the unicast transmission period UT _1' broadcast transmission period BT of the next subsequent occasions broadcast packets BP10 _1, UT ₂ ', ..., the opportunity for sending a unicast packet UP10 _k finally to any of UT _n ' When broadcast packets BP10 ₁ is delivered, is always transmission prohibited period T_NG is immediately, since immediately thereafter the followed broadcast transmission period BT again, as long as the base unit node 10 ₁ is not stopped broadcast packets BP10 _1, child machine node _{10 2, 10 3, ...,} 10 x, ..., any desired transmission node 10 _k of 10 _n is're Prevents sending unicast packets UP10 _k.

FIG. 5 illustrates a case in which unicast transmission between the transmission request nodes 10 _k competes. However, the same process is performed in the conventional CSMA / ACK method. Desired transmission node 10 _k is when I send a unicast packet UP10 _k unicast transmission period UT _2, unicast transmission period in UT ₃ another desired transmission node 10 k _{+ 1} immediately after the unicast packet UP10 k + ₁ Stop sending. If another transmission-desired node 10 _{k + 1} detects an ACK response to the unicast packet UP10 _k and subsequently does not transmit the broadcast packet BP10 ₁ in the broadcast transmission period BT ′, the subsequent unicast transmission period UT ₁ The unicast packet UP10 _{k + 1} is transmitted to any one of ', UT ₂ ', ..., UT _n '(in this case, the unicast transmission period UT ₃ '). Of course, when another unicast packet (in this case, any one of the unicast transmission periods UT ₁ ′, UT ₂ ′, UT ₃ ′) competing with the unicast packet UP10 _{k + 1} occurs, another transmission is performed. detects that desired node 10 k _{+ 1} is the still broadcast packets BP10 ₁ to the next broadcast period BT (not shown) is not sent, only so as apply a retry unicast transmission.

FIG. 6 illustrates a case where unicast transmission between the transmission request nodes 10 _k collides. However, this collision processing is also performed in the conventional CSMA / ACK method as in the description of FIG. It is assumed that the transmission-desired node 10 _k transmits the unicast packet UP10 _k in the unicast transmission period UT ₂ , but another transmission-desired node 10 _{k + 1} has also transmitted the unicast packet UP10 _{k + 1} . Since these two unicast packets UP10 _k and UP10 _{k + 1} collide with each other on the transmission line Ls, the transmission request node 10 _k and another transmission request node 10 _{k + 1} have two transmission prohibition periods T_NG. If it is confirmed that no ACK response is returned, a unicast retransmission opportunity is set at random using random number data or the like, and unicast transmission is attempted.

  In this way, in the CSMA / ACK-type bus-type data transmission system, only a node having broadcast transmission authority for broadcast transmission that does not require an ACK reply immediately after the transmission prohibition period elapses until the next unicast transmission period. Since a broadcast transmission period is set up to allow broadcast packets to be sent, it is the only node that has transmission authority, and broadcast packets can be delivered with priority over any unicast communication. Since broadcast packets do not collide with each other, it is easy to deliver broadcast packets to each node.

Although the node having the right to perform broadcast communication is illustrated as the parent node 10 ₁ , the node having the right to perform broadcast communication may be unique in the bus system, and may not be the parent node 10 _1. Of the other terminals, a specific slave node 10 _x may be used.

(Second embodiment)
FIG. 7 is a time chart showing the generation timing of each packet such as unicast and broadcast and ACK reply flowing in the transmission line Ls. The bus type data transmission system according to the second embodiment is different from the bus type data transmission system according to the first embodiment described above in that the broadcast transmission authority is given when the transmission request node wants to perform broadcast transmission. This is the point that broadcast transmission is delegated to the only node that has it.

Desired transmission node 10 _k wishing to broadcast transmission has no broadcast transmission authorization, the only node with a broadcast transmission authorization master unit node 10 _1.

The desired transmission node 10 _k is, the parent device node 10 _1, and the broadcast transmission proxy request signal Sig_BT_Req to apply to get on behalf of the broadcast transmission of a broadcast transmission period, broadcast content signal Sig_BT_DATA and is a signal representing the contents of the broadcast Are also transmitted as a unicast packet UP10 _k in a unicast transmission period with unicast transmission authority.

Base unit node 10 _1, upon receiving a unicast packet UP10 _k in conjunction with a broadcast transmission proxy request signal Sig_BT_Req and broadcast content signal Sig_BT_DATA, if the good processing state to acknowledge the broadcasts substitute request, the unicast packets In the transmission prohibition period T_NG immediately after receiving UP10 _k , an ACK reply to the effect of accepting the substitution of the broadcast is returned to the transmission-desired node 10 _k . However, the parent device node 10 _1, if the processing state can not understand the broadcast transmission request, ACK reply to the effect that to acknowledge the agency of the broadcast does not reply. The presence or absence of the ACK reply, the desired transmission node 10 _k is whether the base unit node 10 ₁ has approved the broadcast agency, can be identified.

Then, the master unit node 10 _1, the broadcast transmission period BT of next opportunity, already broadcast content signal Sig_BT_DATA already received from the desired transmission node 10 _k, within the bus system (transmission line Ls), broadcasts. After this broadcast transmission is completed, the same processing as in the first embodiment described above is performed, and if a unicast packet UP10 _k including a broadcast transmission proxy request signal Sig_BT_Req is generated in the middle of the broadcast transmission, the same processing is performed as described above. Similar processing is performed.

Thus, as compared with the first embodiment, the desired transmission node 10 _k, due to the addition of the ability to get to on behalf of the broadcast to base unit node 10 _1, any desired transmission node 10 _k parent device node 10 Broadcast communication via _{1 is} possible.

Although the node having the right to perform broadcast communication is illustrated as the parent node 10 ₁ , the node having the right to perform broadcast communication may be unique in the bus system, and may not be the parent node 10 _1. Of the other terminals, a specific slave node 10 _x may be used.

(Third embodiment)
FIG. 8 is a time chart showing the generation timing of each packet such as unicast and broadcast and ACK reply flowing through the transmission line Ls. The bus type data transmission system according to the third embodiment is different from the bus type data transmission systems according to the first and second embodiments described above, and is characterized in that a broadcast is transmitted when a node wishing to transmit broadcasts. The point is that the broadcast authority is borrowed to the only node that has the transmission authority.

The desired transmission node 10 _k is, was placed on the sole of the parent device node 10 ₁ addressed to a node with a broadcast transmission authorization, the broadcast transmission permission request signal Sig_BT_Req_CHG to apply to ask them to allow the broadcast transmission of a broadcast transmission period BT The unicast packet UP10 _k is transmitted in a unicast transmission period with unicast transmission authority.

Base unit node 10 _1, upon receiving a unicast packet UP10 _k carrying the broadcast transmission permission request signal Sig_BT_Req_CHG, if the broadcast application to be processed state note, immediately after receiving the unicast packet UP10 _k In the transmission prohibition period T_NG, an ACK reply to the effect that the lending of broadcast transmission authority is approved is sent to the transmission-desired node 10 _k . However, the parent device node 10 _1, if the processing state can not understand the broadcast transmission authority lending, ACK reply to the effect that to understand the broadcast transmission authorization lending does not reply. The presence or absence of the ACK reply, the desired transmission node 10 _k is whether the base unit node 10 ₁ has approved the broadcast transmission authorization lending can be identified.

Thereafter, the desired transmission node 10 _k is a broadcast transmission period BT for the next opportunity, the broadcast packets BP10 _k to be broadcast by the own apparatus onset, within the bus system (transmission line Ls), broadcasts. In the broadcast transmission period BT, base unit node 10 ₁ is in a transmission inhibiting state broadcasting can not be performed.

After the transmission of the broadcast packet BP10 _k is completed, the same processing as in the first embodiment and the second embodiment described above is performed, and a unicast including a broadcast transmission permission request signal Sig_BT_Req_CHG in the middle thereof. If the packet UP10 _k is generated, the same processing as described above is performed.

Thus, as compared with the second embodiment, the desired transmission node 10 _k, due to the addition of the ability to borrow broadcast rights from the main device node 10 _1, broadcast communication any desired transmission node 10 _k is by the own apparatus origin It will be possible. Therefore, in comparison with the second embodiment, to be able to reduce the burden of transmission processing operations according to the base unit node 10 _1, sent the broadcast content signal Sig_BT_DATA in the second embodiment to the main unit node 10 ₁ No need.

Although the node that lends the right to perform broadcast communication to the transmission-desired node 10 _k is exemplified as the parent node 101 ₁ , the node having the right to perform broadcast communication may be the only node in the bus system. not be the node 10 ₁ of the other terminal may be a specific handset node 10 _x.

(Fourth embodiment)
FIG. 9 is a time chart showing the generation timing of each packet such as unicast and broadcast and ACK reply flowing through the transmission line Ls. The difference between the bus type data transmission system of the fourth embodiment and the bus type data transmission system of the first to third embodiments is that the transmission node continuously transmits broadcast transmission. is there.

Both the master node 10 ₁ in the first or second embodiment and the transmission request node 10 _k in the third embodiment are nodes that have acquired the authority for broadcast transmission. These nodes acquired rights of broadcast transmission, once through the transmission prohibition period T_NG of immediately after the transmission of broadcast packets BP10 _1, BP10 _k, the same broadcast packets BP10 _1, sends the BP10 _k, this broadcast communication Repeat the transmission a predetermined number of times.

However, since it is necessary for the receiving node to recognize how many broadcast packets have the same content, sequence numbers are set in the frame control areas in the broadcast packets BP10 ₁ and BP10 _k . The receiving node compares the sequence numbers of the broadcast packets BP10 ₁ and BP10 _k received immediately before with the newly received broadcast packets BP10 ₁ and BP10 _k and obtains the already received broadcast packets BP10 ₁ and BP10 _k again. If this happens, the broadcast packets BP10 ₁ and BP10 _k are discarded, and the corresponding processing is not performed in the own device.

As for the transmission desired node 10 _k in the third embodiment, Failure negotiated a continuous transmissions times before starting the broadcast transmission in between the master unit node 10 _1, then many times of broadcast transmission period BT master unit node 10 ₁ will resume the broadcast transmission in, there is a risk that a broadcast packet collides from the broadcast packet and base unit node 10 ₁ from a desired transmission node 10 _k. To avoid this, the desired transmission node 10 _k is a continuous transmissions desired number of broadcast, previously apply in advance to the base unit node 10 ₁ included in the broadcast transmission permission request signal Sig_BT_Req_CHG. Specifically, the transmission-desired node 10 _k sets a sequence number in the frame control area in the broadcast transmission permission request signal Sig_BT_Req_CHG. Alternatively, the broadcast transmission permission signal received in the ACK reply is answered with the designated number of continuous broadcasts, and the desired transmission node 10 _k transmits the same broadcast packet continuously for the predetermined number of times. You can do it.

  Thus, since broadcast packets are continuously transmitted, it is possible to increase the probability of successful reception during broadcast communication. For example, even when a transmission failure occurs due to noise or the like, the probability of successful reception at the receiving node can be increased by continuously transmitting broadcast packets.

Although the node having the right to perform broadcast communication is illustrated as the parent node 10 ₁ , the node having the right to perform broadcast communication may be unique in the bus system, and may not be the parent node 10 _1. Of the other terminals, a specific slave node 10 _x may be used.

1 is a system configuration diagram illustrating a bus type data transmission system according to the present invention. FIG. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and ACK reply which flow through the transmission line Ls of 1st embodiment which concerns on this invention. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and ACK reply which flow through the transmission line Ls of 1st embodiment which concerns on this invention. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and ACK reply which flow through the transmission line Ls of 1st embodiment which concerns on this invention. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and ACK reply which flow through the transmission line Ls of 1st embodiment which concerns on this invention. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and ACK reply which flow through the transmission line Ls of 1st embodiment which concerns on this invention. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and ACK reply which flow through the transmission line Ls of 2nd embodiment which concerns on this invention. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and an ACK reply which flow through the transmission line Ls of 3rd embodiment which concerns on this invention. It is a time chart showing generation | occurrence | production timing of each packet, such as unicast and broadcast, and ACK reply which flow through the transmission line Ls of 4th embodiment which concerns on this invention. It is a system block diagram explaining the conventional bus type data transmission system. It is a time chart explaining preventing the collision of ACK replies by subdivision of a transmission prohibition period for the conventional ACK reply detection.

Explanation of symbols

_{10 1, 10 2, 10 3} , 10 k, 10 k + 1, 10 t, 10 x, ..., 10 n nodes Ls transmission path T_NG transmission prohibition period _{UT 1, UT 2, UT 3} , ..., UT n unicast Transmission period ACK ACK reply BP10 ₁ , BP10 _k broadcast packet 10 ₁ Only node having broadcast transmission authority Sig_BT_Req Broadcast transmission proxy request signal Sig_BT_DATA Broadcast content signal Sig_BT_Req_CHG Broadcast transmission permission request signal

Claims (8)

A plurality of nodes whose access is controlled by the CSMA / ACK method are bus-connected to the transmission line, and a node that desires to transmit is set to be approximately equal to the time required for carrier sense after the transmission prohibition period for detecting an ACK reply has elapsed. The unicast packet transmission is performed only at the start of each of the divided unicast transmission periods, and the transmitted node receives the data of the receiving node depending on the presence or absence of an ACK reply indicating an acknowledgment during the transmission prohibited period. In the CSMA / ACK bus type data transmission system that determines the success or failure of a broadcast packet, it has the broadcast transmission authority to transmit a broadcast packet that does not require an ACK reply immediately after the transmission prohibition period elapses until the next unicast packet transmission period. a broadcast transmission period only a single node can be performed provided, broad If the node that wants to perform the broadcast transmission does not have the broadcast transmission authority, this node applies to the only node having the broadcast transmission authority to perform the broadcast transmission during the broadcast transmission period. And the broadcast content signal, which is a signal representing the content of the broadcast, are transmitted at any opportunity in the unicast transmission period, and the only node having the broadcast transmission authority is the broadcast transmission proxy request signal and the broadcast content signal. If the unicast signal is received and the broadcast transmission proxy request is accepted, the received unicast signal is received during the broadcast transmission period of the next opportunity when the unicast signal is received. A broadcast content signal contained in No., characterized in that it broadcasts in the bus system, CSMA communication method. When a node that desires broadcast transmission does not have broadcast transmission authority, this node applies to a single node having broadcast transmission authority to permit broadcast transmission during the broadcast transmission period. The only node that has the broadcast transmission authority can receive the unicast signal including the broadcast transmission permission request signal and accept the broadcast transmission request. If this is the case, the broadcast transmission permission request signal is transmitted by including the broadcast transmission permission signal indicating permission for the broadcast transmission permission request signal in the ACK reply that responds in the transmission prohibition period immediately after this unicast signal. If the received node receives the broadcast transmission permission signal, the node replaces the only node having broadcast transmission authority at least in the broadcast transmission period of the next opportunity after receiving the broadcast transmission permission signal, and broadcasts in the bus system. The CSMA data communication method according to claim 1, wherein the CSMA data communication method is performed by using the CSMA data communication method. A broadcast transmission requesting node impersonating the only node having the broadcast transmission authority transmits the same broadcast signal after the transmission prohibition period immediately after performing the broadcast transmission, and this broadcast transmission permission 3. The CSMA data communication method according to claim 2, wherein the CSMA data communication method is repeated for a predetermined number of times that has been applied for in the request signal or specified in the received broadcast transmission permission signal. A broadcast transmission node device that is the only node device having broadcast transmission authority in the CSMA / ACK scheme, and is set to be substantially equal to the time required for carrier sense after the transmission prohibition period for detecting an ACK reply has elapsed. In addition to being configured to be able to transmit unicast packets only at each start time of a given unicast transmission period, the transmission unicast period and the next unicast after the transmission prohibition period ends A slave node device that is provided during the packet transmission period and is connected to the bus system and controlled for access using the CSMA / ACK method can transmit broadcast packets that do not require an ACK return during the broadcast transmission period when transmission is prohibited. The broadcast transmission node device is unicast If a unicast signal that combines the broadcast transmission proxy request signal and the broadcast content signal is received at any occasion during the transmission period, the unicast signal is received if the broadcast transmission proxy request is acceptable. Broadcast transmission in the CSMA / ACK system, wherein a broadcast content signal included in the received unicast signal is broadcast in the bus system during a broadcast transmission period of the next opportunity received. Node device. A slave node device that is access-controlled by the CSMA / ACK method, and when transmission is desired, it is set and divided approximately equal to the time required for carrier sense after the transmission prohibition period for detecting an ACK reply has elapsed. Unicast packet transmission is performed only at each start point of the unicast transmission period, and between the transmission prohibition period and the next unicast packet transmission period after the transmission prohibition period ends. Transmission is prohibited during a broadcast transmission period in which only a single broadcast transmission node device connected in the bus system and controlled for access by the CSMA / ACK method can transmit. When the broadcast node device wishes to perform broadcast transmission, the broadcast node device A broadcast transmission proxy request signal for applying for broadcast transmission in the broadcast transmission period and a broadcast content signal representing the broadcast content are transmitted together at any opportunity during the unicast transmission period. A slave node device according to the CSMA / ACK system. The broadcast transmission node device acknowledges the broadcast transmission request when receiving a broadcast transmission permission request signal for requesting permission for broadcast transmission in the broadcast transmission period at any opportunity in the unicast transmission period. If the processing state is acceptable, the ACK reply responding in the transmission prohibition period immediately after the unicast signal is transmitted including a broadcast transmission permission signal indicating permission for the broadcast transmission permission request signal, and at least the broadcast transmission permission is transmitted. The broadcast transmission node apparatus according to claim 4, wherein broadcast transmission is not performed in a broadcast transmission period of a next opportunity after receiving a signal. When the slave node device desires broadcast transmission, the slave node device transmits a broadcast transmission permission request signal for applying to the broadcast transmission node device to permit broadcast transmission during the broadcast transmission period. If the ACK reply received from the broadcast transmission node apparatus is included in the transmission prohibition period immediately after the unicast signal, including a broadcast transmission permission signal indicating permission for the broadcast transmission permission request signal, In the broadcast transmission period of the next opportunity at least after receiving the broadcast transmission permission signal, the broadcast transmission node device is broadcasted in place of the broadcast transmission node device. Handset node device according to claim 5. When the slave node device has passed the transmission prohibition period immediately after performing broadcast transmission, it sends out the same broadcast signal, and this broadcast transmission has been applied to be included in the broadcast transmission permission request signal, or The slave node device according to claim 7, wherein the slave node device repeats a predetermined number of times specified in the broadcast transmission permission signal received.

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