JP2007251361A - Ring communication network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ring communication network system capable of properly executing communication by configuring identically each slave station without the need for setting an individual address to each slave station and achieving high speed communication. <P>SOLUTION: A control station and slave stations are connected with a communication bus in a ring form. A form of data transmitted through the communication bus adopts a form of composite packets resulting from connecting data packets each allocated to each of the slave stations in the connection order of the slave stations, and each data packet is provided with a flag area to which a transmission/reception flag is written. Each slave station detects a start position of the data packet in the composite packets, transmits a transmission/reception flag T and discriminates a type of the original transmission/reception flag at the same time, reaches a bus-through state until a start position of a next data packet is detected when the transmission/reception flag is the transmission/reception flag T, receives succeeding reception data and transmits reply data at the same time when the transmission/reception flag is a transmission/reception flag R, and thereafter reaches the bus-through state until a data packet start position of a top of a succeeding composite packets. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ring communication network system in which one control station and a plurality of dependent stations are connected in a ring shape via a communication bus.

  In recent years, with the development of communication network technology, for example, in vehicles such as automobiles, a communication network system has been installed as an important system for realizing integrated control of various electrical components. Various types of communication network systems mounted on vehicles have been proposed. Among them, ring-type communication network systems connect a control station and multiple subordinate stations in series via a ring-shaped communication bus. Therefore, there is an advantage that signal collision does not occur.

  By the way, there is a strong demand for lower prices for vehicles in recent years, and it is an important issue to configure a communication network system mounted on a vehicle as inexpensively as possible. In order to achieve this, each subordinate station connected as a node in a ring communication network system has the same configuration and can perform appropriate communication without setting an individual address for each subordinate station. There has been proposed an attempt to reduce costs by making it possible to centralize manufacture and management of communication equipment as a station (see, for example, Patent Document 1).

In Patent Document 1, a composite packet in which received data addressed to each dependent station is connected from the control station in accordance with the connection order of each dependent station is sent to the communication bus, and each dependent station starts from the composite packet flowing through the communication bus. A technique is described in which data is fetched, reply data to be sent back to the control station is added to the end, and the data is sent to the communication bus.
JP-A-11-163898

  However, in the conventional technique described in Patent Document 1, each dependent station takes the leading data from the composite packet flowing through the communication bus, adds reply data to the control station to the end, and adds it to the communication bus. Since it was configured to transmit, as the communication required time required to transmit data bidirectionally between the control station and each dependent station, the time to transmit data from the control station to each dependent station, A separate time must be set for the time at which data is returned from each subordinate station to the control station, and until the control station finishes a series of transmission / reception cycles, the total time of these times is added. There is a problem that it is necessary and it is difficult to increase the communication speed.

  The present invention was devised to solve the above-described problems of the prior art, and allows each dependent station to have the same configuration and perform appropriate communication without setting individual addresses. At the same time, a ring communication network system is provided in which the communication time required for bi-directionally transmitting data between the control station and each dependent station is shortened, and the communication speed can be increased. The purpose is that.

  In the present invention, the format of the signal flowing through the communication bus is the composite packet format. A composite packet is a combination of a plurality of data packets corresponding to the number of a plurality of subordinate stations serving as network nodes in accordance with the connection order of a plurality of subordinate stations. Each data packet constituting the composite packet includes A data area in which received data to be received by the dependent station or reply data from the dependent station to the control station is written, and whether the data added to the head of the data area and written in the data area is received data is returned. A flag area in which a transmission / reception flag for identifying whether it is data is written is set.

  In the present invention, the control station receives the reception data that each dependent station should receive in the data area of each data packet, and the data written in the subsequent data area in the flag area is the reception data that each dependent station should receive. And a communication control means for receiving a composite packet that flows through the communication bus at the same time as writing a composite packet to the communication bus. On the other hand, each of the plurality of dependent stations controls data communication by the composite packet while switching between a transmission state in which some data is written and transmitted in the data packet constituting the composite packet and a bus-through state in which the data packet is passed through as it is. Communication control means.

  Then, when the communication control means provided in each of the plurality of dependent stations detects the start position of the data packet in the composite packet, it shifts from the bus-through state to the transmission state, and the subsequent data is transferred to the flag area of the data packet. A flag indicating that the data written in the area is reply data is written, and at the same time, the original transmission / reception flag written in the flag area is received and its type is determined. If the communication control means provided in each of the plurality of dependent stations is a flag indicating that the original transmission / reception flag written in the flag area indicates that the data written in the subsequent data area is return data. From the transmission state to the bus-through state, the bus-through state is maintained until the start position of the next data packet is detected. On the other hand, if the original transmission / reception flag written in the flag area indicates that the data written in the subsequent data area is reception data, the reception data written in the subsequent data area is At the same time as receiving, after writing the reply data to the control station in the data area where the received data was written, transition from the transmission state to the bus-through state, the start position of the first data packet in the next composite packet The bus-through state is maintained until the signal is detected.

  According to the present invention, each dependent station has the same configuration, and communication between the control station and each dependent station can be appropriately performed without setting an individual address for each dependent station. Cost reduction can be realized. Further, according to the present invention, since the control station and each dependent station can simultaneously receive and transmit data in the composite packet format, data can be transmitted bidirectionally between the control station and each dependent station. The required communication time required for transmission can be shortened, and communication speed can be increased.

  Hereinafter, specific embodiments of a ring communication network system to which the present invention is applied will be described in detail with reference to the drawings.

[First Embodiment]
<Overall configuration>
FIG. 1 is a diagram schematically showing an overall configuration of a ring communication network system according to a first embodiment to which the present invention is applied. In the ring communication network system of the present embodiment, one control station M1 and three dependent stations (first dependent station S11, second dependent station S12, and third dependent station S13) serve as communication nodes as network nodes. 101, 102, 103 and 104 are connected in a ring shape. In this ring communication network system, the control station M1 as a node and the three dependent stations S11, S12, S13 are connected in series, and the signal flow is determined in one direction. That is, the transmission port TP of the control station M1 and the reception port RP of the first dependent station S11 are connected by the communication bus 101, and the transmission port TP of the first dependent station S11 and the reception port RP of the second dependent station S12 communicate with each other. The transmission port TP of the second dependent station S12 and the reception port RP of the third dependent station S13 are connected by the bus 102, and the transmission port TP of the third dependent station S13 and the reception port of the control station M1 are connected by the communication bus 103. The RP is connected to the communication bus 104. The third dependent station S1 from the control station M1 via the communication bus 101, the second dependent station S12 from the first dependent station S11 via the communication bus 102, and the third dependent station S12 from the second dependent station S12 via the communication bus 103. A signal sequentially flows from the dependent station S13 and the third dependent station S13 to the control station M1 via the communication bus 104.

<Composite packet>
In the ring communication network system of this embodiment, the format of the signal flowing through the communication buses 101, 102, 103, and 104 is a composite packet format as shown in FIG. The composite packet shown in FIG. 2 is a combination of three data packets corresponding to the number of dependent stations S11, S12, and S13. The first data packet is assigned to the first dependent station S11, The data packet is assigned for the second dependent station S12, and the last data packet is assigned for the third dependent station S13. That is, the composite packet is obtained by changing the three data packets respectively assigned to the dependent stations S11, S12, and S13 according to the connection order of the dependent stations S11, S12, and S13 along the signal flow from the control station M1. It is connected.

  Each data packet constituting the composite packet has a data area and a flag area added to the head of the data area. The data area is an area in which received data transmitted from the control station M1 and to be received by the dependent stations S11, S12, S13, or return data from the dependent stations S11, S12, S13 to the control station M1 is written. The flag area is an area in which a transmission / reception flag for identifying whether the data written in the subsequent data area is reception data or reply data is written.

  In addition, a communication start signal (SOM: Start Of Message) indicating the start of communication by the composite packet is added to the head of the composite packet, and the start position of the composite packet can be specified by this SOM. Yes.

<Outline of control station and dependent stations>
In the ring communication network system of this embodiment, the control station M1 and the three subordinate stations S11, S12, and S13, which are nodes, perform data communication using composite packets in addition to the transmission port TP and the reception port RP, respectively. Communication control means for controlling is provided.

  The communication control means of the control station M1 transmits the data (received data) addressed to each of the dependent stations S11, S12, S13 from the transmission port TP in the composite packet format, and at the same time from each of the dependent stations S11, S12, S13 in the composite packet format. It has a function of receiving the reply data sent from the reception port RP.

  Specifically, when starting the communication, the communication control means of the control station M1 first sends an SOM indicating the start of communication by the composite packet from the transmission port TP onto the communication bus 101, and then the subsequent Transmission / reception flag (hereinafter referred to as transmission / reception flag R) indicating that the data is reception data to be received by the dependent station, reception data addressed to the first dependent station S11, transmission / reception flag R, reception addressed to the second dependent station S12 The data, the transmission / reception flag R, and the reception data addressed to the third dependent station S13 are sequentially sent out on the communication bus 101 from the transmission port TP. Among the combinations of the transmission / reception flag R and the reception data sequentially transmitted from the transmission port TP of the control station M1 onto the communication bus 101, the combination of the transmission / reception flag R and the reception data transmitted first is the first subordinate station S11. Is a data packet assigned for the second dependent station S12, and the combination of the transmission / reception flag R and the reception data sent next is the data packet data assigned for the second dependent station S12. A combination of the flag R and the received data is data of the data packet allocated for the third dependent station S13. That is, as shown in FIG. 3A, the communication control means of the control station M1 writes the transmission / reception flag R in the flag area and the reception data RX1 addressed to the first subordinate station S11 in the data area following the SOM, respectively. Data packet, data packet in which transmission / reception flag R is written in the flag area, reception data RX2 addressed to the second dependent station S12 is written in the data area, transmission / reception flag R in the flag area, and reception addressed to the third dependent station S13 in the data area Data packets in which the data RX3 is written are transmitted in this order from the transmission port TP onto the communication bus 101, thereby transmitting data in a composite packet format.

  In addition, the communication control means of the control station M1 has a function of simultaneously transmitting data from the transmission port TP and receiving data from the reception port RP. While transmitting, the data in the composite packet format flowing on the communication bus 104 is sequentially received from the reception port RP. That is, the communication control means of the control station M1, as shown in FIG. 3B, transmits / receives a flag indicating that the subsequent data in the flag area is reply data from the subordinate station following the SOM (hereinafter referred to as transmission / reception). This is called a flag T.), a data packet in which the reply data TX1 from the first dependent station S11 is written in the data area, a transmission / reception flag T in the flag area, and a reply data TX2 from the second dependent station S12 in the data area. Each of the written data packets and the data packet in which the transmission / reception flag T is written in the flag area and the reply data TX3 from the third dependent station S13 are written in the data area are received in this order from the reception port RP.

  The communication control means of the dependent stations S11, S12, and S13 are configured in common with each other, receive reception data addressed to the own station from the control station M1 from the reception port RP, and simultaneously send return data to the control station M1 as a transmission port. A transmission state that has a function of transmitting from the TP, writes some data in the data packet constituting the composite packet and transmits it from the transmission port TP, and a bus through that passes the data received at the reception port RP as it is to the transmission port TP The data communication by the composite packet is controlled while switching the state.

  Specifically, when the communication control means of each dependent station S11, S12, S13 receives the SOM of the composite packet flowing through the communication buses 101, 102, 103 at the reception port RP, it determines the start of communication by the composite packet. The data communication by the composite packet is controlled by performing the following processing on each data packet constituting the composite packet. That is, when the start position of the data packet in the composite packet is detected, the communication control means of each subordinate station S11, S12, S13 shifts from the bus-through state to the transmission state, and transmits / receives a flag to the flag area of the data packet. At the same time when T is written and transmitted from the transmission port TP, the type of the original transmission / reception flag written in the flag area is determined. If the original transmission / reception flag written in the flag area is the transmission / reception flag T, the communication control means of each control station S11, S12, S13 uses the data packet for the dependent station upstream of the own station. It is determined that the data packet is allocated, transitions from the transmission state to the bus-through state, maintains the bus-through state until the start position of the next data packet is detected, and is written to the subsequent data area. Through the received data from the reception port RP to the transmission port TP. Then, when the start position of the next data packet is detected, the state transits again from the bus-through state to the transmission state, and the above-described processing is repeated.

  On the other hand, if the original transmission / reception flag written in the flag area is the transmission / reception flag R, it is determined that the data packet is a data packet assigned to the local station, and the reception data written in the subsequent data area is received. At the same time that the data is received from the reception port RP, the reply data to the control station M1 is written in the data area in which the reception data has been written and transmitted from the transmission port TP, and then the state shifts from the transmission state to the bus-through state. The bus through state is maintained until the start position of the first data packet in the next composite packet is detected, and the data of the subsequent data packet is passed from the reception port RP to the transmission port TP. The start position of the top data packet in the composite packet can be detected by the SOM added to the head of each composite packet. The start position of the data packet other than the top data packet in each composite packet is For example, if the data area in each data packet is set to a fixed length, the next data is determined based on the elapsed time after shifting to the bus-through state by measuring the elapsed time after shifting to the bus-through state. The start position of the packet can be detected.

  In the ring communication network system of the present embodiment, the communication control means of each dependent station S11, S12, S13 performs the processing as described above, so that the control station M1 using the composite packet and each dependent station S11, S12. , S13 can be appropriately performed in two-way data communication.

  That is, when the control station M1 sends a composite packet as shown in FIG. 3A to the communication bus 101, the first subordinate station S11 performs the above-described processing on the communication bus 101 by the communication control means. The received data RX1 addressed to the own station written in the data area of the leading data packet is received from the flowing composite packet as shown in FIG. 3A, and at the same time, the reply data TX1 to the control station M1 is received in this data area. Is sent to the communication bus 102 as a composite packet shown in FIG.

  In addition, the second dependent station S12 performs the above-described processing by the communication control unit, so that the composite packet as shown in FIG. 3C flowing on the communication bus 102 is transferred to the data area of the second data packet. Simultaneously with receiving the received reception data RX2 addressed to the own station, the return data TX2 to the control station M1 is written in this data area and sent to the communication bus 103 as a composite packet shown in FIG.

  In addition, the third dependent station S13 performs the above-described processing by the communication control unit, so that the composite packet as shown in FIG. 3D flowing on the communication bus 103 is transferred to the data area of the third data packet. At the same time that the received reception data RX3 addressed to the own station is received, reply data TX3 to the control station M1 is written in this data area and sent to the communication bus 104 as a composite packet as shown in FIG. . Then, the control station M1 receives the reply data TX1, TX2, TX3 from the subordinate stations S11, S12, S13 from the composite packet as shown in FIG. 3B flowing on the communication bus 104.

  As described above, in the ring communication network system of the present embodiment, the dependent stations S11, S12, and S13 have the same configuration, and individual addresses are not set in the dependent stations S11, S12, and S13. Data communication between the control station M1 and each of the dependent stations S11, S12, S13 can be appropriately performed while maintaining a so-called address-free state. Therefore, according to the ring type communication network system of the present embodiment, it is possible to centralize the manufacture and management of the communication devices that are the subordinate stations S11, S12, and S13, thereby realizing cost reduction.

  In the ring communication network system of the present embodiment, the control station M1 and each of the dependent stations S11, S12, S13 can simultaneously receive and transmit data in the composite packet format. It is possible to reduce the time required for communication required for bi-directionally transmitting data between the subordinate stations S11, S12, and S13, and it is possible to increase the communication speed.

<Specific configuration example of dependent stations>
Here, in the ring communication network system of the present embodiment as described above, refer to FIG. 4 for a specific configuration example of the communication control means for realizing the processing described above in each of the dependent stations S11, S12, S13. Further details will be described. In the ring communication network system according to the present embodiment, since the subordinate stations S11, S12, and S13 have the same configuration as described above, the configuration and operation of the communication control means described below are also common. . Therefore, in the following, the dependent stations S11, S12, and S13 are collectively referred to as the dependent station S, and the preceding communication bus connected to the reception port RP is defined as the communication bus N, and the subsequent communication bus connected to the transmission port TP. The communication bus M will be described.

  FIG. 4 is a block diagram illustrating an example of a specific internal configuration of the dependent station S. The subordinate station S illustrated in FIG. 4 includes SOM detection circuit 1, transmission / reception flag transmission circuit 2, transmission / reception flag detection circuit 3, through timer 4, transmission / reception control circuit 5, as specific components constituting communication control means. A communication data receiving circuit 6, a communication data transmitting circuit 7, a transmission timer 8, a transmission selection control circuit 9, and a transmission selection circuit 10 are provided.

  In this dependent station S, a communication signal input from the communication bus N to the reception port RP connected to the communication bus N is sent to the SOM detection circuit 1, the transmission / reception flag detection circuit 3, the communication data reception circuit 6, The signal is distributed to the transmission selection circuit 10 as a reception signal.

  When detecting the SOM from the received signal, the SOM detection circuit 1 outputs the SOM detection signal to the transmission / reception flag transmission circuit 2 and the transmission selection control circuit 9.

  When the SOM detection signal output from the SOM detection circuit 1 is input, the transmission / reception flag transmission circuit 2 starts transmission of the transmission / reception flag T and outputs it to the transmission selection circuit 10 as an internal transmission signal. The transmission / reception flag transmission circuit 2 also starts transmission of the transmission / reception flag T and outputs it as an internal transmission signal to the transmission selection circuit 10 when a later-described through end signal output from the through timer 4 is input. To do.

  When the transmission / reception flag detection circuit 3 detects the transmission / reception flag T from the reception signal, the transmission / reception flag detection circuit 3 outputs the T reception signal to the through timer 4 and the transmission selection control circuit 9. When the transmission / reception flag detection circuit 3 detects the transmission / reception flag R from the reception signal, the transmission / reception flag detection circuit 3 outputs the R reception signal to the transmission / reception control circuit 5.

  When the T reception signal output from the transmission / reception flag detection circuit 3 is input, the through timer 4 starts a timer count and is determined by the communication data length of the data area of each data packet constituting the composite packet. A through end signal is output to the transmission / reception flag transmission circuit 2 and the transmission selection control circuit 9 at the timing when the transmission of the reception data addressed to the other dependent stations is completed.

  The transmission / reception control circuit 5 receives a transmission / reception start signal when an R reception signal output from the transmission / reception flag detection circuit 3 is input when a transmission selection signal described later output from the transmission selection control circuit 9 is in a transmission state. The data is output to the communication data receiving circuit 6, the communication data transmitting circuit 7, and the transmission timer 8.

  When the transmission / reception start signal output from the transmission / reception control circuit 5 is input, the communication data reception circuit 6 receives a reception signal from the reception port RP, that is, reception data sent from the control station M1 to the own station. Start.

  When the transmission / reception start signal output from the transmission / reception control circuit 5 is input, the communication data transmission circuit 7 starts transmission of reply data to the control station M1, and outputs the reply data to the transmission selection circuit 10 as an internal transmission signal. To do.

  The transmission timer 8 starts the timer count when the transmission / reception start signal output from the transmission / reception control circuit 5 is input, and is determined by the communication data length of the data area of each data packet constituting the composite packet. At the timing when transmission of reply data addressed to the control station M1 is completed, a transmission status end signal is output to the transmission selection control circuit 9.

  The transmission selection control circuit 9 always outputs a transmission selection signal indicating that it is in either a transmission state or a bus-through state to the transmission / reception control circuit 5 and the transmission selection circuit 10 and outputs it according to the situation. The content of the transmission selection signal to be switched is switched. That is, the transmission selection control circuit 9 outputs a transmission selection signal indicating a bus through state in the idle state and the initial state, and outputs a SOM detection signal output from the SOM detection circuit 1 or a through end signal output from the through timer 4. Is input, the output transmission selection signal is used as a transmission selection signal indicating a transmission state. Further, the transmission selection control circuit 9 receives the T reception signal output from the transmission / reception flag detection circuit 3 or the transmission state end signal output from the transmission timer 8 while outputting the transmission selection signal indicating the transmission state. Then, the output transmission selection signal is used as a transmission selection signal indicating a bus-through state.

  If the transmission selection signal output from the transmission selection control circuit 9 indicates a transmission state, the transmission selection circuit 10 represents the internal transmission signal (representing the transmission / reception flag T or the transmission / reception flag R) output from the transmission / reception flag transmission circuit 2. Signal) and an internal transmission signal output from the communication data transmission circuit 7 (a signal representing reply data to the control station M1) is output as a transmission signal to the transmission port TP. Further, the transmission selection circuit 10 selects the communication signal of the reception port RP connected to the communication bus N (transmission selection from the reception port RP) if the transmission selection signal output from the transmission selection control circuit 9 indicates a through state. The reception signal distributed to the circuit 10) is output as a transmission signal to the transmission port TP. The transmission signal output to the transmission port TP is transmitted as a communication signal on the communication bus M connected to the transmission port TP.

<Specific example of operation of first dependent station>
Next, a specific example of the operation of the first dependent station S11 having the internal configuration illustrated in FIG. 4 will be described with reference to FIG.

  FIG. 5 is a timing chart showing a series of operations when the first dependent station S11 having the internal configuration illustrated in FIG. 4 performs data communication using the composite packet. Note that the composite packet shown in the upper part of FIG. 5 is a composite packet that represents a communication signal (received signal) that flows through the communication bus 101 and is input to the reception port RP of the first dependent station S11. The illustrated composite packet is a composite packet representing a transmission signal transmitted from the transmission port TP of the first dependent station S11 onto the communication bus 102.

  As shown in FIG. 5, when a communication signal flowing in the form of a composite packet on the communication bus 101 is input to the reception port RP of the first dependent station S11, the SOM detection circuit 1 first starts in the first dependent station S11. The head SOM of the composite packet is detected and an SOM detection signal is output. As a result, the transmission selection signal output from the transmission selection control circuit 9 is switched from the signal indicating the bus-through state to the signal indicating the transmission state, and at the same time, the transmission / reception flag transmission circuit 2 outputs the transmission / reception flag T as an internal transmission signal. Then, the data is sent out on the communication bus 102 from the transmission port TP.

  At the same time when the transmission / reception flag transmission circuit 2 finishes transmitting the transmission / reception flag T, the transmission / reception flag detection circuit 3 detects the transmission / reception flag R, outputs the R reception signal, and the transmission / reception control circuit 5 outputs the transmission / reception start signal. Then, the communication data receiving circuit 6 and the communication data transmitting circuit 7 are activated, and the communication data receiving circuit 6 receives the reception signal from the communication bus 101 (received data RX1 sent from the control station M1 to the own station). At the same time, the reply data TX1 to the control station M1 is output as an internal transmission signal by the communication data transmission circuit 7 and sent out from the transmission port TP onto the communication bus 102. When the transmission of the reply data TX1 by the communication data transmission circuit 7 is started, the transmission timer 8 is started.

  Simultaneously with the end of transmission of the reply data TX1 by the communication data transmission circuit 7, a transmission state end signal is output by the transmission timer 8, and the transmission selection signal output from the transmission selection control circuit 9 is bus-through from the signal indicating the transmission state. It is switched to a signal indicating the state. Thereafter, until the SOM detection circuit 1 detects the SOM of the next composite packet, the transmission selection control circuit 9 is in a bus state even if the transmission / reception flag R is detected by the transmission / reception flag detection circuit 3 and the R reception signal is output. A transmission selection signal indicating the through state is output, and the bus through state is maintained until the first data packet in the next composite packet is input to the reception port RP.

<Specific example of operation of second dependent station>
Next, a specific example of the operation of the second dependent station S12 having the internal configuration illustrated in FIG. 4 will be described with reference to FIG.

  FIG. 6 is a timing chart showing a series of operations when the second dependent station S12 having the internal configuration illustrated in FIG. 4 performs data communication using composite packets. The composite packet shown in the upper part of FIG. 6 is a composite packet that represents a communication signal (received signal) that flows through the communication bus 102 and is input to the reception port RP of the second dependent station S12. The illustrated composite packet is a composite packet representing a transmission signal transmitted from the transmission port TP of the second dependent station S12 onto the communication bus 103.

  As shown in FIG. 6, when a communication signal flowing in the form of a composite packet on the communication bus 102 is input to the reception port RP of the second dependent station S12, the SOM detection circuit 1 first starts in the second dependent station S12. The head SOM of the composite packet is detected and an SOM detection signal is output. As a result, the transmission selection signal output from the transmission selection control circuit 9 is switched from the signal indicating the bus-through state to the signal indicating the transmission state, and at the same time, the transmission / reception flag transmission circuit 2 outputs the transmission / reception flag T as an internal transmission signal. Then, the data is transmitted from the transmission port TP onto the communication bus 103.

  At the same time as the transmission / reception flag T is completely transmitted by the transmission / reception flag transmission circuit 2, the transmission / reception flag detection circuit 3 detects the transmission / reception flag T and outputs a T reception signal. The selection signal is switched from the signal indicating the transmission state to the signal indicating the bus-through state, and the reply data TX1 from the first dependent station S11 input to the reception port RP to the control station M1 is transmitted to the transmission port TP. Simultaneously with the transmission on the communication bus 103, the through timer 4 is started.

  Thereafter, the through timer 4 outputs a through end signal simultaneously with the end of transmission of the reply data TX from the first dependent station S11 to the control station M1, and the transmission selection signal output from the transmission selection control circuit 9 is in the bus through state. The transmission / reception flag transmission circuit 2 outputs the transmission / reception flag T as an internal transmission signal and is transmitted from the transmission port TP onto the communication bus 103.

  Simultaneously with the end of transmission of the transmission / reception flag T by the transmission / reception flag transmission circuit 2, the transmission / reception flag detection circuit 3 detects the transmission / reception flag R, and the transmission / reception control circuit 5 outputs a transmission / reception start signal. The communication data transmission circuit 7 is activated, and the communication data reception circuit 6 receives the reception signal from the communication bus 102 (the reception data RX2 transmitted from the control station M1 to the own station). 7, the reply data TX2 to the control station M1 is output as an internal transmission signal, and is sent out on the communication bus 103 from the transmission port TP. When the transmission of the reply data TX2 by the communication data transmission circuit 7 is started, the transmission timer 8 is started.

  Simultaneously with the end of transmission of the reply data TX2 by the communication data transmission circuit 7, a transmission state end signal is output by the transmission timer 8, and the transmission selection signal output from the transmission selection control circuit 9 is bus-through from the signal indicating the transmission state. It is switched to a signal indicating the state. Thereafter, until the SOM detection circuit 1 detects the SOM of the next composite packet, the transmission selection control circuit 9 is in the bus even if the transmission / reception flag R is detected by the transmission / reception flag detection circuit 3 and the R reception signal is output A transmission selection signal indicating the through state is output, and the bus through state is maintained until the first data packet in the next composite packet is input to the reception port RP.

<Specific example of the operation of the third dependent station>
Next, a specific example of the operation of the third dependent station S13 having the internal configuration illustrated in FIG. 4 will be described with reference to FIG.

  FIG. 7 is a timing chart showing a series of operations when the third dependent station S13 having the internal configuration illustrated in FIG. 4 performs data communication using composite packets. The composite packet shown in the upper part of FIG. 7 is a composite packet that represents a communication signal (received signal) that flows through the communication bus 103 and is input to the reception port RP of the third dependent station S13. The illustrated composite packet is a composite packet representing a transmission signal transmitted from the transmission port TP of the third dependent station S13 onto the communication bus 104.

  As shown in FIG. 7, when a communication signal flowing in the form of a composite packet on the communication bus 103 is input to the reception port RP of the third dependent station S13, the SOM detection circuit 1 first starts in the third dependent station S13. The head SOM of the composite packet is detected and an SOM detection signal is output. As a result, the transmission selection signal output from the transmission selection control circuit 9 is switched from the signal indicating the bus-through state to the signal indicating the transmission state, and at the same time, the transmission / reception flag transmission circuit 2 outputs the transmission / reception flag T as an internal transmission signal. Then, the data is transmitted from the transmission port TP onto the communication bus 104.

  At the same time as the transmission / reception flag T is completely transmitted by the transmission / reception flag transmission circuit 2, the transmission / reception flag detection circuit 3 detects the transmission / reception flag T and outputs a T reception signal. The selection signal is switched from the signal indicating the transmission state to the signal indicating the bus-through state, and the reply data TX1 from the first dependent station S11 input to the reception port RP to the control station M1 is transmitted to the transmission port TP. Simultaneously with the transmission on the communication bus 104, the through timer 4 is started.

  Thereafter, the through timer 4 outputs a through end signal simultaneously with the end of transmission of the reply data TX1 from the first dependent station S11 to the control station M1, and the transmission selection signal output from the transmission selection control circuit 9 is in the bus through state. The transmission / reception flag transmission circuit 2 outputs the transmission / reception flag T as an internal transmission signal and is transmitted from the transmission port TP onto the communication bus 104.

  At the same time as the transmission / reception flag T is completely transmitted by the transmission / reception flag transmission circuit 2, the transmission / reception flag detection circuit 3 detects the transmission / reception flag T and outputs a T reception signal. The selection signal is switched again from the signal indicating the transmission state to the signal indicating the bus-through state, and the reply data TX2 from the second subordinate station S12 input to the reception port RP to the control station M1 is transmitted to the transmission port TP. At the same time as being sent out on the communication bus 104, the through timer 4 is started.

  Thereafter, the through timer 4 outputs a through end signal simultaneously with the end of transmission of the reply data TX2 from the second dependent station S12 to the control station M1, and the transmission selection signal output from the transmission selection control circuit 9 is in the bus through state. The transmission / reception flag transmission circuit 2 outputs the transmission / reception flag T as an internal transmission signal and is transmitted from the transmission port TP onto the communication bus 104.

  Simultaneously with the end of transmission of the transmission / reception flag T by the transmission / reception flag transmission circuit 2, the transmission / reception flag detection circuit 3 detects the transmission / reception flag R, and the transmission / reception control circuit 5 outputs a transmission / reception start signal. And the communication data transmission circuit 7 are activated, and the communication data reception circuit 6 receives the reception signal (reception data RX3 transmitted from the control station M1 to the local station) from the communication bus 103, and at the same time, the communication data transmission circuit 7, the reply data TX3 to the control station M1 is output as an internal transmission signal, and is sent out on the communication bus 104 from the transmission port TP. When the transmission of the reply data TX3 by the communication data transmission circuit 7 is started, the transmission timer 8 is started.

  Simultaneously with the end of transmission of the reply data TX3 by the communication data transmission circuit 7, a transmission state end signal is output by the transmission timer 8, and the transmission selection signal output from the transmission selection control circuit 9 is bus-through from the signal indicating the transmission state. It is switched to a signal indicating the state.

<Effect>
As described above in detail with specific examples, according to the ring communication network system of the present embodiment, the first dependent station S11, the second dependent station S12, and the third dependent station S13 are identical to each other. Since the communication between the control station M1 and each of the dependent stations S11, S12, and S13 can be appropriately performed without setting an individual address for each of the dependent stations S11, S12, and S13, It is possible to unify the manufacture and management of communication devices that become the subordinate stations S11, S12, and S13, thereby realizing cost reduction. Further, according to the ring communication network system of the present embodiment, the control station M1 and each of the dependent stations S11, S12, S13 can simultaneously receive and transmit data in the composite packet format. It is possible to reduce the time required for communication required to transmit data bidirectionally between M1 and each of the dependent stations S11, S12, S13, and to realize high speed communication.

[Second Embodiment]
Next, a ring communication network system according to a second embodiment to which the present invention is applied will be described. In the ring communication network system of the present embodiment, a plurality of dependent stations that are nodes of the network are grouped by dependent stations having the same shared address, and the dependent station group and the control station belonging to each group communicate with each other. Each is connected in a ring shape via a bus. Then, the communication control means of the control station adds the address information indicating the shared address to the composite packet and sends it to the communication bus, and the communication control means provided in each of the plurality of dependent stations indicates the address indicating the shared address of the own station. Data communication using the composite packet is controlled for the composite packet to which information is added.

  The other parts in the ring communication network system of this embodiment, that is, the basic parts of the configuration and operation of the control station and each dependent station are the same as those in the first embodiment described above. Now, only the characteristic part of the present embodiment will be described, and the description of the same part as the first embodiment will be omitted.

<Overall configuration>
FIG. 8 is a diagram schematically showing the overall configuration of the ring communication network system of the second embodiment. The ring communication network system of this embodiment includes one control station M2 and nine dependent stations (first dependent station S21, second dependent station S22, third dependent station S23, fourth dependent station S24, and fifth dependent station). S25, sixth dependent station S26, seventh dependent station S27, eighth dependent station S28, and ninth dependent station S29) are provided as network nodes. Of the nine dependent stations, the first dependent station S21, the second dependent station S22, and the third dependent station S23 are assigned a shared address AD1 and are grouped as a first dependent station group SG1, The fourth dependent station S24, the fifth dependent station S25, and the sixth dependent station S26 are assigned a shared address AD2 and grouped as a second dependent station group SG2, and the seventh dependent station S27 and the eighth dependent station S26 are grouped together. The station S28 and the ninth dependent station S29 are assigned a shared address AD3 and are grouped as a third dependent station group SG3.

  In the ring communication network system of the present embodiment, the control station M2 and the first dependent station S21, the second dependent station S22, and the third dependent station S23 that form the first dependent station group SG1 are communication buses 201 and 202. , 203, 204 are connected in a ring shape. That is, the transmission port TP of the control station M2 and the reception port RP of the first dependent station S21 are connected by the communication bus 201, and the transmission port TP of the first dependent station S21 and the reception port RP of the second dependent station S22 communicate with each other. The transmission port TP of the second dependent station S22 and the reception port RP of the third dependent station S23 are connected by the bus 202, and the transmission port TP of the third dependent station S23 and the reception port of the control station M2 are connected by the communication bus 203. The RP is connected to the communication bus 204. Then, the control station M2 receives the third dependent station S21 via the communication bus 201, the first dependent station S21 via the communication bus 202, the second dependent station S22, and the second dependent station S22 via the communication bus 203. A signal sequentially flows from the dependent station S23 and the third dependent station S23 to the control station M2 via the communication bus 204.

  In the ring communication network system of the present embodiment, the control station M2 and the fourth dependent station S24, the fifth dependent station S25, and the sixth dependent station S26 constituting the second dependent station group SG2 are connected to the communication bus 201. , 205, 206, 204 are connected in a ring shape. That is, the transmission port TP of the control station M2 and the reception port RP of the fourth dependent station S24 are connected by the communication bus 201, and the transmission port TP of the fourth dependent station S24 and the reception port RP of the fifth dependent station S25 communicate with each other. The transmission port TP of the fifth dependent station S25 and the reception port RP of the sixth dependent station S26 are connected by the bus 205, and the transmission port TP of the sixth dependent station S26 and the reception port of the control station M2 are connected by the communication bus 206. The RP is connected to the communication bus 204. Then, from the control station M2 to the fourth dependent station S24 via the communication bus 201, from the fourth dependent station S24 to the fifth dependent station S25 via the communication bus 205, and from the fifth dependent station S25 via the communication bus 206 to the sixth slave station. A signal sequentially flows from the dependent station S26 and the sixth dependent station S26 to the control station M2 via the communication bus 204.

  In the ring communication network system of the present embodiment, the control station M2 and the seventh dependent station S27, the eighth dependent station S28, and the ninth dependent station S29 constituting the third dependent station group SG3 are connected to the communication bus 201. , 207, 208 and 204 are connected in a ring shape. That is, the transmission port TP of the control station M2 and the reception port RP of the seventh dependent station S27 are connected by the communication bus 201, and the transmission port TP of the seventh dependent station S27 and the reception port RP of the eighth dependent station S28 communicate with each other. The transmission port TP of the eighth dependent station S28 and the reception port RP of the ninth dependent station S29 are connected by the bus 207, and the transmission port TP of the ninth dependent station S29 and the reception port of the control station M2 are connected by the communication bus 208. The RP is connected to the communication bus 204. Then, the control station M2 is connected to the seventh dependent station S27 via the communication bus 201, from the seventh dependent station S27 via the communication bus 207 to the eighth dependent station S28, and from the eighth dependent station S28 via the communication bus 208 to the ninth. A signal sequentially flows from the dependent station S29 and the ninth dependent station S29 to the control station M2 via the communication bus 204.

<Composite packet>
In the ring communication network system of this embodiment, the format of the signal flowing through the communication buses 201, 202, 203, 204, 205, 206, 207, 208 is the composite packet format as shown in FIG. The composite packet shown in FIG. 9 includes address information for specifying the first to third dependent station groups SG1, SG2, and SG3 described above in the composite packet described in the first embodiment (see FIG. 2). An address area (Address Area) that is an area to be written is added. This address area is provided between the head SOM in the composite packet and the subsequent three data packets.

<Outline of control station and dependent stations>
In the ring communication network system of this embodiment, the communication control means of the control station M2 adds address information to the address area of the composite packet in addition to the function of the communication control means of the control station M1 described in the first embodiment. It has a function of writing and sending it out on the communication bus 201.

  Specifically, when the communication control means of the control station M2 starts communication with each of the dependent stations S21, S22, S23 constituting the first dependent station group SG1, first, communication using a composite packet is performed. Address information indicating the shared address AD1 assigned to each of the dependent stations S21, S22, S23 constituting the first dependent station group SG1. Is transmitted from the transmission port TP onto the communication bus 201. After that, as in the first embodiment, the transmission / reception flag R, the reception data addressed to the first dependent station S21, the transmission / reception flag R, the reception data addressed to the second dependent station S22, the transmission / reception flag R, the addressing to the third dependent station S23 Received data is sequentially transmitted from the transmission port TP onto the communication bus 201. That is, when the communication control means of the control station M2 transmits the reception data addressed to each of the dependent stations S21, S22, S23 constituting the first dependent station group SG1, as shown in FIG. Following the SOM, the address information indicating the shared address AD1, the transmission / reception flag R in the flag area, the data packet in which the reception data RX1 addressed to the first dependent station S21 is written in the data area, and the transmission / reception flag R, data in the flag area A data packet in which the reception data RX2 addressed to the second dependent station S22 is written in the area, a transmission / reception flag R in the flag area, and a data packet in which the reception data RX3 addressed to the third dependent station S23 is written in the data area, Sending data in the composite packet format by sending the data from the transmission port TP to the communication bus 201 in order. Cormorant.

  In addition, when the communication control means of the control station M2 starts communication with each of the dependent stations S24, S25, S26 constituting the second dependent station group SG2, first, the communication control means starts the communication by the composite packet. SOM to be sent is transmitted from the transmission port TP to the communication bus 201, and then address information indicating the shared address AD2 assigned to each of the dependent stations S24, S25, S26 constituting the second dependent station group SG2 is transmitted to the transmission port. The data is transmitted from the TP onto the communication bus 201. Thereafter, the transmission / reception flag R, the reception data addressed to the fourth dependent station S24, the transmission / reception flag R, the reception data addressed to the fifth dependent station S25, the transmission / reception flag R, and the reception data addressed to the sixth dependent station S26 are sequentially transmitted to the transmission port TP. To the communication bus 201. That is, when the communication control means of the control station M2 transmits the reception data addressed to each of the dependent stations S24, S25, S26 constituting the second dependent station group SG2, as shown in FIG. Following the SOM, the address information indicating the shared address AD2, the transmission / reception flag R in the flag area, the data packet in which the reception data RX4 addressed to the fourth subordinate station S24 is written, and the transmission / reception flag R, data in the flag area A data packet in which the reception data RX5 addressed to the fifth dependent station S25 is written in the area, a data packet in which the transmission / reception flag R is written in the flag area, and the reception data RX6 addressed to the sixth dependent station S26 is written in the data area. Sending data in the composite packet format by sending the data from the transmission port TP to the communication bus 201 in order. Cormorant.

  Further, when the communication control means of the control station M2 starts communication with each of the dependent stations S27, S28, S29 constituting the third dependent station group SG3, first, the communication control means starts the communication by the composite packet. The SOM shown is sent from the transmission port TP to the communication bus 201, and then address information indicating the shared address AD3 assigned to each of the dependent stations S27, S28, S29 constituting the third dependent station group SG3 is sent to the transmission port. The data is transmitted from the TP onto the communication bus 201. Thereafter, the transmission / reception flag R, the reception data addressed to the seventh dependent station S27, the transmission / reception flag R, the reception data addressed to the eighth dependent station S28, the transmission / reception flag R, and the reception data addressed to the ninth dependent station S29 are sequentially transmitted to the transmission port TP. To the communication bus 201. That is, when the communication control means of the control station M2 transmits received data addressed to each of the dependent stations S27, S28, S29 constituting the third dependent station group SG3, as shown in FIG. Following the SOM, the address information indicating the shared address AD3, the data packet in which the transmission / reception flag R is written in the flag area, the reception data RX7 addressed to the seventh subordinate station S27 is written in the data area, and the transmission / reception flag R, data in the flag area A data packet in which the reception data RX8 addressed to the eighth dependent station S28 is written in the area, a transmission / reception flag R in the flag area, and a data packet in which the reception data RX9 addressed to the ninth dependent station S29 is written in the data area, Sending data in the composite packet format by sending the data from the transmission port TP to the communication bus 201 in order. Cormorant.

  Further, the communication control means of the control station M2 simultaneously transmits data from the transmission port TP and receives data from the reception port RP, similarly to the communication control means of the control station M1 described in the first embodiment. Based on the address information written in the address area of the composite packet, the data received from the reception port RP in the form of the composite packet is the data from which dependent station group. Judgment.

  In the ring communication network system according to the present embodiment, the communication control means of the dependent stations S21, S22, S23, S24, S25, S26, S27, S28, and S29 are configured in common with each other, and the first embodiment. In addition to the function of the communication control means of the dependent stations S11, S12, and S13 described in the above, it is determined from the address information added to the composite packet whether the composite packet is addressed to the group of dependent stations to which the local station belongs. Transporting functions.

  That is, the first subordinate station S21 belonging to the first subordinate station group SG1 has the case where the address information added to the composite packet flowing on the communication bus 201 indicates the shared address AD1 assigned to the own station. Only the operation similar to that of the first dependent station S11 described in the first embodiment is performed. Further, the second dependent station S22 belonging to the first dependent station group SG1 has a case where the address information added to the composite packet flowing on the communication bus 202 indicates the shared address AD1 assigned to the own station. Only the operation similar to that of the second dependent station S12 described in the first embodiment is performed. Further, the third subordinate station S23 belonging to the first subordinate station group SG1 has the case where the address information added to the composite packet flowing on the communication bus 203 indicates the shared address AD1 assigned to the own station. Only, the same operation as the third dependent station S13 described in the first embodiment is performed.

  Further, the fourth dependent station S24 belonging to the second dependent station group SG2 is configured such that the address information added to the composite packet flowing on the communication bus 201 indicates the shared address AD2 assigned to the own station. Only the operation similar to that of the first dependent station S11 described in the first embodiment is performed. Further, the fifth subordinate station S25 belonging to the second subordinate station group SG2 determines that the address information added to the composite packet flowing on the communication bus 205 indicates the shared address AD2 assigned to the own station. Only the operation similar to that of the second dependent station S12 described in the first embodiment is performed. Further, the sixth subordinate station S26 belonging to the second subordinate station group SG2 determines that the address information added to the composite packet flowing on the communication bus 206 indicates the shared address AD2 assigned to the own station. Only, the same operation as the third dependent station S13 described in the first embodiment is performed.

  In addition, the seventh dependent station S27 belonging to the third dependent station group SG3 has a case where the address information added to the composite packet flowing on the communication bus 201 indicates the shared address AD3 assigned to the own station. Only the operation similar to that of the first dependent station S11 described in the first embodiment is performed. Further, the eighth dependent station S28 belonging to the third dependent station group SG3 has a case where the address information added to the composite packet flowing on the communication bus 207 indicates the shared address AD3 assigned to the own station. Only the operation similar to that of the second dependent station S12 described in the first embodiment is performed. Further, the ninth subordinate station S29 belonging to the third subordinate station group SG3, when the address information added to the composite packet flowing on the communication bus 208 indicates the shared address AD3 assigned to the own station. Only, the same operation as the third dependent station S13 described in the first embodiment is performed.

<Effect>
As described above, according to the ring communication network system of the present embodiment, each of the dependent stations S21, S22, S23, S24, S25, which are connected as network nodes, as in the first embodiment described above. Appropriate data communication with the control station M2 can be performed while the S26, S27, S28, and S29 have the same configuration, and each of the dependent stations S21, S22, S23, S24, S25, S26, S27, and S28. , S29 can be integrated into the manufacturing and management of the communication equipment, the cost can be reduced, and the control station M2 and the subordinate stations S21, S22, S23, S24, S25, S26, S27, S28, S29 and It is possible to reduce the time required for communication in order to transmit data in both directions between them, and to realize high-speed communication.

  In the ring communication network system of the present embodiment, the dependent stations S21, S22, S23, S24, S25, S26, S27, S28, and S29 connected as network nodes are identified by the shared addresses AD1, AD2, and AD3. Grouped into three subordinate station groups SG1, SG2, SG3, and each subordinate station group SG1, SG2, SG3 is an individual communication system independent of other subordinate station groups. It is possible to effectively avoid the inconvenience that communication between all the dependent stations and the control station is interrupted, and to minimize the influence of the failure of the dependent station on the other dependent stations.

[Modification]
As described above, the first embodiment and the second embodiment have been described as specific examples of the ring communication network system to which the present invention is applied. However, each of the above embodiments exemplifies an application example of the present invention. The technical scope of the present invention is not limited to the contents disclosed in the description of the above embodiments, and various alternative techniques that can be easily derived from these disclosures are also included. .

  For example, the first embodiment shows an example including three subordinate stations as network nodes, and the second embodiment includes nine subordinate stations as network nodes, and these nine subordinate stations include three subordinate stations. Although an example of grouping into groups is shown, the number of dependent stations connected as a network node and the number of dependent station groups are arbitrary, the number of data packets constituting a composite packet is the number of dependent stations, Alternatively, any number can be accommodated by matching the number of dependent stations constituting one dependent station group.

  In the first and second embodiments, the communication control means of each dependent station has shifted to the bus-through state using a through timer or the like as a method for detecting the start position of the data packet other than the head data packet in the composite packet. The method of measuring the elapsed time later and detecting the start position of the next data packet based on the elapsed time after shifting to the bus-through state is exemplified. The data length transmitted from the reception port RP to the transmission port TP by counting through may be counted (bit count) to detect the start position of the next data packet. Further, if a packet end flag indicating the end of the data packet is added to the end of each data packet constituting the composite packet, the next is based on the packet end flag added to the end of each data packet. It is also possible to detect the start position of the data packet. If the start position of the next data packet is detected based on the packet end flag, the data area of each data packet that constitutes the composite packet can be made variable in length to perform more efficient communication. It becomes possible.

1 is a diagram illustrating an overall configuration of a ring communication network system according to a first embodiment to which the present invention is applied. It is a figure which shows the format of the composite packet used with the ring type communication network system of 1st Embodiment. It is a figure which shows the composite packet which flows through a communication bus in the ring type communication network system of 1st Embodiment, (a) is a figure which shows the composite packet sent on a communication bus from the transmission port of a control station, (b) Fig. 5 is a diagram showing a composite packet sent from the transmission port of the third dependent station to the communication bus and received at the receiving port of the control station, and (c) is sent out from the transmission port of the first dependent station onto the communication bus. The figure which shows a composite packet, (d) is a figure which shows the composite packet sent on the communication bus from the transmission port of a 2nd subordinate station. It is a block diagram which shows the specific example of the internal structure of a dependent station. 5 is a timing chart showing a series of operations when a first dependent station having the internal configuration shown in FIG. 4 performs data communication using a composite packet. 5 is a timing chart showing a series of operations when a second dependent station having the internal configuration shown in FIG. 4 performs data communication using a composite packet. 5 is a timing chart showing a series of operations when a third dependent station having the internal configuration shown in FIG. 4 performs data communication using composite packets. It is a figure which shows the whole structure of the ring type communication network system of 2nd Embodiment to which this invention is applied. It is a figure which shows the format of the composite packet used with the ring type communication network system of 2nd Embodiment. FIG. 10 is a diagram showing a composite packet sent from a transmission port of a control station to a communication bus in the ring communication network system of the second embodiment, and (a) is addressed to each dependent station constituting the first dependent station group. The figure which shows the composite packet in the case of transmitting the receiving data of (b), (b) is a figure which shows the composite packet in the case of transmitting the reception data addressed to each dependent station constituting the second dependent station group, (c) is the first It is a figure which shows the composite packet in the case of transmitting the reception data addressed to each dependent station which comprises 3 dependent station groups.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 SOM detection circuit 2 Transmission / reception flag transmission circuit 3 Transmission / reception flag detection circuit 4 Through timer 5 Transmission / reception control circuit 6 Communication data reception circuit 7 Communication data transmission circuit 8 Transmission timer 9 Transmission selection control circuit 10 Transmission selection circuit 101-104, 201-208 Communication bus M1, M2 Control station S11-S13, S21-S29 Dependent station SG1-SG3 Dependent station group RP Receive port TP Transmit port

Claims (5)

In a ring communication network system in which one control station and a plurality of subordinate stations are connected in a ring shape via a communication bus,
The format of the signal flowing through the communication bus includes a data area in which received data to be received by the dependent station or reply data from the dependent station to the control station is written, and the data area added to the head of the data area. A data packet having a flag area in which a transmission / reception flag for identifying whether the data written in the received data is the received data or the reply data is defined as one unit, and corresponds to the number of the plurality of dependent stations A plurality of data packets are combined in accordance with the connection order of the plurality of dependent stations, and are in the form of a composite packet;
The control station writes received data to be received by each dependent station in the data area of each data packet, and data written in a subsequent data area in the flag area of each data packet is received. A communication control means for writing a flag indicating data and sending the composite packet to the communication bus as the composite packet and simultaneously receiving the composite packet flowing through the communication bus,
Communication control in which each of the plurality of dependent stations controls data communication by the composite packet while switching between a transmission state in which some data is written and transmitted in the data packet and a bus-through state in which the data packet is directly passed through. With means,
The communication control means provided in each of the plurality of dependent stations includes:
When the start position of the data packet in the composite packet is detected, the data shifts from the bus-through state to the transmission state, and the data written in the subsequent data area in the flag area of the data packet is the return data. At the same time as writing the flag indicating that it is, the original transmission / reception flag written in the flag area is received and its type is determined,
If the original transmission / reception flag written in the flag area is a flag indicating that the data written in the subsequent data area is the reply data, the state shifts from the transmission state to the bus-through state. The bus-through state is maintained until the start position of the next data packet is detected,
If the original transmission / reception flag written in the flag area is a flag indicating that the data written in the subsequent data area is the received data, the received data written in the subsequent data area is Simultaneously with reception, after writing the reply data to the control station in the data area where the received data has been written, the state shifts from the transmission state to the bus-through state, and the first data packet in the next composite packet The ring-type communication network system is characterized in that the bus-through state is maintained until the start position of the network is detected. A communication start signal indicating the start of communication is added to the top of the composite packet,
The communication control means provided in each of the plurality of dependent stations detects a start position of a head data packet in the composite packet based on a communication start signal added to the head of the composite packet. Item 4. A ring communication network system according to item 1.   The communication control means provided in each of the plurality of dependent stations measures an elapsed time after transitioning to the bus-through state, and detects a start position of each data packet in the composite packet based on the measured elapsed time The ring communication network system according to claim 1, wherein: A packet end flag indicating the end of each data packet is added to the end of each data packet in the composite packet,
The communication control means provided in each of the plurality of dependent stations detects the start position of the next data packet based on a packet end flag added to the end of each data packet. The ring communication network system described. The plurality of dependent stations are grouped by dependent stations having the same shared address, and the dependent station group belonging to each group and the control station are respectively connected in a ring shape via the communication bus,
The communication control means of the control station adds address information indicating the shared address to the composite packet and sends it to the communication bus,
2. The communication control means provided in each of the plurality of dependent stations controls data communication using the composite packet for a composite packet to which address information indicating a shared address of the local station is added. The ring type communication network system described in 1.

Images