Address setting method and communication system to which the address setting method is applied

Abstract: Communication stations(3) whose own addresses coincide with a destination address of communication data(31) received via data transmission lines(5) and whose write enable/disable states of their own addresses stored in their address/flag memory(21) are in their write enable states can update their own addresses to variably set address values of the communication data, then update their own address write enable/disable states to their write disable states, then execute predetermined calculations for the variably set address value in the communication data(31), and then transmit the communication data(3) whose variably set address value has been rewritten into the variably set address value obtained by the calculations to succeeding stations(3) so as to circulate between a plurality of communication stations(3) sequentially.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present Invention relates to an address setting method for use in a communication system, which is constructed by connecting a plurality of communication stations mutually via data transmission lines in a data exchangeable manner, and capable of allocating/setting own addresses to enable mutual discrimination of their identity. More particularly, the present invention relates to an address setting method capable of setting their own addresses to a plurality of communication stations by simple process procedures respectively and also capable of improving throughput as a whole communication system upon setting the address, and a communication system to which the address setting method is applied. 2. Description of the Prior Art In the prior art, there has been commonly known a communication system which is constructed by connecting a plurality of communication stations mutually via data transmission lines in a data exchangeable manner. In the above communication system in the prior art, upon carrying out data exchange between the communication stations mutually, addresses to enable mutual discrimination of their own identity must be allocated and set previously to the communication stations respectively. Therefore, in the prior art, as disclosed in Patent Application Publication (KOKAI) Hei 4-326896, for example, there has been publicly known an address setting method for use in a communication system in which at least one master apparatus and a plurality of slave apparatuses are connected to a common communication bus. In the communication system disclosed in the above Publication, each of the slave apparatuses comprises a storing means for storing its own communication address updatably and a connection requesting means for transmitting its own connection request information to the master apparatus upon starting the communication system, while the master apparatus comprises a communication address setting means for setting the communication address of the slave apparatus in such a way that such set communication address can be discriminated from those in other slave units and for informing the concerned slave apparatus of such set communication address when it receives the connection requesting information. According to the communication system, the convection requesting means of the slave apparatus transmits its own connection request information to the master apparatus upon starting the communication system, while the communication address setting means of the master apparatus sets the communication address of the slave apparatus in such a way that such set communication address can be discriminated from those in other slave units and then informs the concerned slave apparatus of such set communication address when it receives the connection requesting information. Therefore, even though a plurality of slave apparatuses are connected on the same communication bus, the address to enable mutual discrimination of their identity can be set without fail to each slave apparatus. However, according to the address setting method in the above communication system in the prior art, the master apparatus, when receives the connection requesting information from respective slave apparatuses, has allocated/set the communication address to/in the slave apparatus in such a way that such set communication address can be discriminated from those in other slave units and then returned/informed the set communication address to/of the concerned slave apparatus individually. Therefore, the address setting method in the prior art has contained such a problem to be overcome that process procedures for exchanging the data including the connection requesting information, the communication address, etc. between the master apparatus and the plurality of slave apparatuses individually are complicated. Furthermore, a total sum of time consumed to carry out the data exchange individually, i.e., a time requested for address setting has tended to become longer. As a result, the address setting method in the prior art has also contained another problem to be overcome that it is difficult to improve throughput as a whole communication system upon setting addresses. Further prior art under Art. 54(3) and (4) EPC is EP 0 903 893 A2 disclosing an address setting method and communication system with a relay station whose own address coincides with a destination address of communication data and whose own address write enable/disable state is in a write enable state. Further, its own address can be updated in a variably set address value in the communication data and the method comprises the step of updating the own address write enable/disable state into the write disable state, executing predetermined calculations of the variably set address value in the communication data and transmitting the communication data to a succeeding relay station. SUMMARY OF THE INVENTION The present invention has been made in light of the above circumstances, and it is an object of the present invention to provide an address setting method which is capable of setting their own addresses to a plurality of communication stations by simple process procedures respectively and also capable of improving throughout as a whole communication system upon setting the address, and a communication system to which the address setting method is applied. According to the present invention the object is achieved by an address setting method having the features of independent claims 1. According to the present invention, at first the plurality of communication stations initialize their own addresses stored in their own address storing means provided in the plurality of communication stations respectively to a predetermined value which is common to the plurality of communication stations, and also initialize their own address write enable/disable states stored in their state storing means provided in the plurality of communication stations respectively to their write enable states, when own address allocating/setting process for each of the plurality of communication stations constituting the communication system is started. Then, any one of the plurality of communication stations transmits the communication data, in which a Predetermined value which is common to the plurality of communication station is described in their destination address portions, in which a destination address of the communication station as a destination of the communication data is described, and also in which a variably set address as any initial value is described in a variably set address description area in which the variably set address to be allocated/set to the plurality of communication stations respectively is described, to one communication station of the plurality of communication stations. Then, the plurality of communication stations including the any one of the plurality of communication stations update their own addresses stored in the own address storing means to the variably set address value described in the variably set address description area of the communication data and also update their own address write enable/disable states to their write disable states when their own addresses coincide with the destination address of the communication data received via the data transmission line end their write enable /disable states of their own addresses stored in the state storing means are in their write enable states, then execute predetermined calculations for the variably set address value described in the variably set address description area of the communication data, then describe the variably set address value calculated by the calculations in the variably set address description area of the communication data, and then transmit the communication data whose variably set address value has been rewritten to succeeding stations. Like the above, according to the present invention, the communication station whose own address coincides with the destination address of the communication data received via the data transmission line and whose write enable/disable state of own address stored in a state storing means is in its write enable state can update its own address to the variably set address value described in the variably set address description area of the communication data, then update its write enable/disable state of its own address to the write disable state, then executes predetermined calculations for the variably set address value described in the variably set address description area of the communication data, then describes the variably set address value calculated by this calculation in the variably set address description area of the communication data, and then transmits the communication data whose variably set address value has been rewritten to the next station so as to circulate between the plurality of communication stations sequentially. Therefore, their own addresses can be set to a plurality of communications stations by simple process procedures respectively and also throughput as a whole communication system upon setting the address can be improved. In other preferred embodiments additional advantages are achieved with the features of the dependent claims. According to a preferred embodiment of the present invention, at first the plurality of communication stations initialize their own addresses stored in their own address storing means provided in the plurality of communication stations respectively to a predetermined value which is common to the plurality of communication stations, and also initialize their own address write enable/disable states stored in their state storing means provided in the plurality of communication stations respectively to their write enable states, when own address allocating/setting process for each of the plurality of communication stations constituting the communication system is started. Then, a system control means, which is connected to any one communication station of the plurality of communication stations and manages integratedly their own address allocating/setting processes of the plurality of communication stations respectively, transmits the communication data, in which a predetermined value, which is common to the plurality of communication stations, is described in their destination address portions, in which a destination address of the communication station as a destination of the communication data is described, and also in which a variably set address as any initial value is described in a variably set address description area in which the variably set address to be allocated/set to the plurality of communication stations respectively is described, to the one communication station. Then, the plurality of communication stations including the any one of the plurality of communication stations update their own addresses stored in the own address storing means to the variably set address value described in the variably set address description area of the communication data and update their own address write enable/disable states to their write disable states when their own addresses coincide with the destination address of the communication data received via the data transmission line and their write enable/disable states of their own addresses stored in the state storing means are in their write enable states, then execute predetermined calculations for the variably set address value described in the variably set address description area of the communication data, then describe the variably set address value calculated by the calculations in the variably set address description area of the communication data, and then transmit the communication data whose variably are address value has been rewritten to succeeding stations. In this manner, according to the present invention, like the above invention, their own addresses can be set to a plurality of communication stations by simple process procedures respectively and also throughput as a whole communication system upon setting the address can be improved. In addition to the above, since the system control means which can manage integratedly their own address allocating/setting processes of the plurality of communication stations respectively is provided as a separate body from the communication stations, common configurations of the plurality of communication stations can be adopted. As a result, fabrication cost of the overall communication system can be reduced. Further, the object is achieved by a communication system having the features of independent claim 6. According to the present invention, at first the initializing means initializes its own address which is stored in the own address storing means provided in the plurality of communication stations respectively to a predetermined value which is common to the plurality of communication stations and also initializes its own address write enable/disable state stored in the state storing means provided in the plurality of communication stations respectively to its write enable state when their own address allocating/setting processes for the plurality of communication stations constituting the communication system respectively are started. Then, the initial data transmitting means transmits the communication data in which a predetermined value which is common to the plurality of communication stations is described in the destination address portion, and also in which a variably set address as any initial value is described in the variably set address description area to one communication station of the plurality of communication stations including its own communication station, and the communication data receiving means receives the communication data via the data transmission line. Then, when their own addresses coincide with the destination address of the communication data received via the data transmission line and their write enable/disable states of their own addresses stored in the state storing means are in their write enable states, the updating means update their own addresses stored in the own address storing means to the variably set address value described in the variably set address description area of the communication data and also updates their own address write enable/disable states stored in the state storing means to their write disable states. Then, the communication data transmitting means executes predetermined calculations for the variably set address value described in the variably set address description area of the communication data, then describes the variably set address value calculated by the calculations in the variably set address description area of the communication data, and then transmits the communication data whose variably set address value has been rewritten to succeeding stations. In this manner, according to the present invention, the communication station whose own address coincides with the destination address of the communication data received via the data transmission line and whose write enable/disable state of own address stored in a state storing means is in its write enable state can update its own address to the variably set address value described in the variably set address description area of the communication data, then update its write enable/disable state of its own address to the bite disable state, then executes predetermined calculations for the variably set address value described in the variably set address description area of the communication data then describes the variably set address value calculated by this calculation in the variably set address description area of the communication data, and then transmits the communication data whose variably set address value has been rewritten to the next station so as to circulate between the plurality of communication stations sequentially. Therefore, their own addresses can be set to a plurality of communication stations by simple process procedures respectively and also throughput as a whole communication system upon setting the address can be improved. In another preferred embodiment additional advantages are achieved. According to an aspect of the present invention, at first the initializing means initializes its own address which is stored in the own address storing means provided in the plurality of communication stations respectively to a predetermined value which is common to the plurality of communication stations and also initializes its own address write enable/disable state stored in the state storing means provided in the plurality of communication stations respectively to its write enable state when their own address allocating/setting processes for the plurality of communication station constituting the communication system respectively are started. Then, the initial data transmitting means provided in the system control means transmits the communication data in which a predetermined value which is common to the plurality of communication stations is described in the destination address portion, and also in which a variably set address as any initial value is described in the variably set address description area to one communication station of the plurality of communication stations including its own communication station, and the communication data receiving means receives the communication data via the data transmission line. Then, when their own addresses coincide with the destination address of the communication data received via the data transmission line and their write enable/disable states of their own addresses stored in the state storing means are in their write enable states, the updating means updates their own addresses stored in the own address storing means to the variably set address value described in the variably set address description area of the communication data and also updates their own address write enable/disable states stored in the state storing means to their write disable states. Then, the communication data transmitting means executes predetermined calculations for the variably set address value described in the variably set address description area of the communication data, then describes the variably set address value calculated by the calculations in the variably set address description area of the communication data, and then transmits the communication data whose variably set address value has been rewritten to succeeding stations. In this fashion according to the present invention, like the above invention, their own addresses can be set to a plurality of communication stations by simple process procedures respectively and also throughput as a whole communication system upon setting the address can be improved. In addition to the above, since the system control means which can manage integratedly their own address allocating/setting processes of the plurality of communication stations respectively is provided as a separate body from the communication stations, common configurations of the plurality of communication stations can be adopted and as a result fabrication cost of the overall communication system can be reduced. The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: FIG. 1 is a schematic block diagram showing a configuration of a communication system to which an address setting method according to the present invention is applied; FIG. 2 is a block diagram showing a communication station as a pertinent portion of the communication system according to the present invention; FIG.3 is a block diagram showing a configuration of a system control unit (SCU) constituting a part of the communications system according to the present invention; FIG. 4 is a view showing an example of a format of communication data used in the communication system according to the present invention; and FIG. 5 is a flowchart showing process procedures of the address setting method according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS An address setting method and a communication system to which the address setting method is applied according to embodiments of the present invention will be explained in detail with reference to the accompanying drawings hereinafter. As shown in FIG. 1, a communication system 1 to which an address setting method according to the present invention is applied is constructed by connecting a plurality of communication stations 3-0, 3-1,.... 3-Y (where Y is a positive integer) mutually via a bus type data transmission line 5 in a data exchangeable manner. To the communication station 3-0 is connected a system control unit (abbreviated as "SCU" hereinafter) 7 as zu system control means which can manage integratedly synchronous control of the overall communications system 1, address setting process for respective communication stations constituting the communication system 1 and respective functional devices N to be described later, etc. As network topology of the communication system 1, an appropriate topological type, for example, loop type star type, or the like may be employed other than the above bus type. One or more than two functional devices N1 to NX (where X is a positive integer) are connected to each of the plurality of communication stations respectively. The communication system 1 is constructed to enable the data exchange between the communication actions, the functional devices N, or the communication station and the functional device N mutually via the data transmission line 5. For example, if the communication system according to the present invention 1 is applied to a vehicle, various functional devices such as a mobile telephone, a facsimile (FAX), a digital TV, a radio receiver, a navigation unit (NV), a DVD (Digital Video Disc or Digital Versatile Disc) - ROM drive, a CD (Compact Disc)-ROM drive, a DAT (Digital Audio Taperecorder), a MD (Mini Disc) drive, an audio amplifier having a built-in digital signal processor, a CAN (Controller Area Network) interface, various sensors such as an azimuth sensor, a speed sensor etc., a monitor device, a vehicle-equipped personal computer, etc. may be employed appropriately as the functional devices N. A format of communication data which are circulated in the present communication system I will be explained with reference to FIG. 4. A plurality of information description areas in which various information are described are set in a signal frame of a communication data 31. The plurality of information description areas are composed of a destination address area 33 in which an address of a destination communications station as a destination of the communication data is described, a source address area 35 in which an address of a source communication station as a source of the communication data is described, a variably set address description area 37 in which an address as a set object for respective communication stations is described as a variably set address K, a set number accumulated value description area 39 in which an accumulated value A of the address setting number carried out repeatedly when any communication failure is caused during the address set process is described, and a data area (not shown) in which various instructions, control information, source data, etc. are described. Next, while taking as an example the case the above formatted communication data are transmitted from the communication station 3-0 acting as the source communication station to a plurality of communication stations 3-1, ... , 3-Y except for the communication station 3-1 with the use of the communication station 3-1 as a representative communication station, a block configurations of each communication station executing major functions in the present communication system 1 will be explained with reference to FIG.2 hereinbelow. As shown in FIG.2, the communication station 3-1 comprises a transmitting/receiving interface (referred to as a transmitting/receiving I/F hereinafter) 9, a buffer memory 11, a decoder 13, a power-on reset circuit 15, an address/flag memory 21 including an own address storing area 17 and a lock flag (LF) storing area 19, and an arithmetic unit 23. The transmitting/receiving I/F 9 receives the communication data which are sent out via the bus type data transmission line 5, while transmits the communication data whose variably set address K out of various information has been selectively updated in its own station to a succeeding communication station via the data transmission line 5. The buffer memory 11 stores temporarily the communication data which have been received by the transmitting/receiving I/F 9. The address/flag memory 21 is composed of RAM, etc., and has the own address storing area 17 for storing its own address of the communications station 3-1 per se, and the lock flag (LF) storing area 19 for storing a write enable/disable state for its own address. The power-on reset circuit 15 generates a reset signal which can initialize stored contents of the buffer memory 11 and the address/flag memory 21 into predetermined values respectively when a power supply of the present communication system 1 is turner on. The decoder 13 decodes various information including the destination communication address which has been described in the destination address area 33 in the communication data 31 read out from the buffer memory 11, and then decides whether or not the decoded destination address coincide with its own address of the communication station 3-1, itself stored in the address/flag memory 21. As a result of this coincidence decision, if the destination address coincides with its own address, the decoder 13 then decides a state of the lock flag (LF) which is read out from the lock flag (LF) storing area 19 of the address/flag memory 21. As a result of this state decision, if the lock flag (LF) is in its own address write enable state (LF=0), the decoder 13 then decodes the variably set address K in the communication data 31 as its own address and then stores the address K in the own address storing area 17 of the address/flag memory 21. The arithmetic unit 23 calculates K+1 by incrementing the variably set address K sent out from the decoder 13 by one to update, and then sends out the updated value K+1 to the buffer memory 11. In turn, a block configuration of the SCU 7 connected to the source communication station 3-0 will be explained with reference to FIG.3 hereinbelow. The SCU 7 comprises a set number deciding unit 25, a reset signal generator 27, and an address setting portion 29. The set number deciding unit 25 has an initializing function of initializing the accumulated value A of the address set number to "0" as an initial value, an accumulated value storing function of incrementing the set number accumulated value A by one every time when the address set process is carried out and then storing the updated set number accumulated value A in an accumulated value storing portion (not shown), and a set number deciding function of deciding based on the set number accumulated value A stored in the accumulated value storing portion whether or not the address set process at this time is effected for the first time and also deciding whether or not the updated set number accumulated value A has come up to a re-set upper limit which is set to an appropriate value, e.g., "3", or so. The reset signal generator 27 generates a reset signal when the power supply of the communication system 1 is turned on or when it has been decided by the set number deciding unit 25 that the address set process at this time is not effected for the first time, i.e., such address set process is a re-set process. The address setting portion 29 sets the destination address, the source address and the variably set address K to predetermined values respectively when the address set process is commenced, and also sends out the communication data including various address information, the set number accumulated value A, and address set commands to the communication station 3-0. Next, referring, to as an example the case the communication data are transmitted from the communication station 3-0 acting as the source communication station to the plurality of destinations communication stations 3-I,..., 3-Y except for the communication station 3-0, process procedures in the address setting method which is applied to the present communication system 1 will be explained with reference to FIG.5 hereinbelow. At first, when the power supply of the communication system 1 is turned on, the power-on reset circuits 15 in the communications stations 3 generate the reset signals respectively. Based on respective reset signals, stored contenis in the buffer memories 11 and the address/flag memories 21 are initialized to predetermined values respectively (step S1). More particularly, According to this initialization process, in respective communication stations 3, the stored contents in the buffer memories 11 are cleared, and their own addresses of respective stations stored in the own address storing area 17 of the address/flag memory 21 are set to a predetermined address, e.g., "00", etc. which is common to all communication stations 3, and a write enable/disable state of their own address stored in the lock flag (LF) storing area 19 is initialized to a write enable state (LF=0). Then, the set number deciding unit 25 of the SCU 7 connected to the source communication station 3-0 initializes the set number accumulated value A to "0" (step S2). After this initialization, the set number deciding unit 25 increments the set number accumulated value A by one and then stores the updated set number accumulated value A in the accumulated value storing portion (step S3). Then, the set number deciding unit 25 of the SCU 7 decides whether or not the set number accumulated value A stored in the accumulated value storing portly is "1" (step S4). As a result of this decision, if it has been decided that the set number accumulated value A is "1", the address setting portion 29 sets "00" as the destination address described in the destination address Area 33, the source address described in the source address area 35, and the variably set address K described in variety set address description area 37 respectively (step S5). Then, the SCU 7 sends out the communication data including various address information, the set number accumulated value A described in the set number accumulated value description area 39, and address set commands to the communication station 3-0 (step S6). The processes in above steps S2 to S6 are executed sequentially on the SCU 7 side. Meanwhile, a flow of the process in respective communication stations 3 will be explained hereunder. When the transmitting/receiving I/Fs 9 in respective communications stations 3 receive the communication data which are sent out from the SCU 7 during a standby state to receive the communication data or which are sent out from one of the destination communication stations except for the source communication station 3-0,they stone the received communication data in the buffer memory 11. At that time, the decoder 13 decodes various information including the destination address, the source address, the variably set address K, and the set number accumulated value A described in the information description areas of the communication data being read out from the buffer memory 11, and also decides whether or not the decoded destination address (00) coincides with own address of its own station stored in the address/flag memory 21. As a result of coincidence decision, if the destination address coincides with own address, the decoder 13 then decides a state of the lock flag (LF) read out from the lock flag (LF) storing area 19 of the address/flag memory 21 (step S7). As a result of state decision in step S7, if the lock flag (LF) of a captain communication station which has received the communication data is in its write enable state (LF=0) of its own address, the decoder 13 then employs the variably set address K described in the communication data as its own address and then stores the address K in the own address storing area 17 of the address/flag memory 21 (step S8). When the own address setting process has been completed in step S8, the decoder 13 sets the lock flag (LF) into its own address write disable state (LF=1) by inverting the state of the lock flag (LF) stored in the lock flag (LF) storing area 19 of the address/flag memory 21. Also, the arithmetic unit 23 calculates k+1 by incrementing the variably set address K sent out from the decoder 13 by one, then updates the value of the variably set address K into K+1, and then sends out the value K+1 to the buffer memory 11 (step S9). As a result, out of the described contents of the communication data stored in the buffer memory 11, the value of the variably set address K is updated into K+1 and then stored. If the process in step S9 has been completed, the transmitting/receiving I/F 9 transmits the communication data whose variably set address K of various information has been selectively updated in own station to a succeeding communication station, in which "00" has been temporarily set as the destination address, via the data transmission line 5 (step S10). When the transmission process in step S10 has been completed, a flow of the process returns to step S7 and then following processes are executed repeatedly. In contrast, as a result of the state decision in step S7, if the lock flag (LF) of the communication station which has received the communication data is in its own address write disable states (LF=1), i.e. , if own address of its own station has already been set, the decoder 13 decides whether or not its own address of own station stored in the address/flag memory 21 coincides with the destination address (00) described in the communication data (step S11). As a result of coincidence decision in step S11, if own address and the source address coincide with each other, i.e., if own address of the communication station in which "00" is set as its own address has already been set and also own station is the source station, the decoder 13 can recognize the effect that the address setting process has been normally completed. Then, in answer to the effect, the transmitting/receiving I/F 9 transmits to the SCU 7 the normally set complete signal including the effect that the address setting process has been normally completed. Then, when the SCU 7 has received the normally set complete signal, it then terminates all address setting processes. As a result of coincidence decision in step S11, if its own address does not coincide with the source address, i.e., if own address of its own station in which "00" is set as own address has already been set and own station is not the source station, the decoder 13 recognizes the effect that address failure such that own address of its own station has erroneously been set, etc. has been generated. In response to this, the transmitting/receiving I/F 9 then transmits the abnormally set generating signal including the effect that address set failure occurs to the SCU 7 via the data transmission line 5 and the source communication station 3-0. Then, the SCU 7, which has received the abnormally set generating signal, then executes sequentially the address re-set process to be described later in the following steps S3. More particularly, the set number deciding unit 25 of the SCU 7 increments the set number accumulated value A stored in the accumulated value storing portion by one and then stores the updated set number accumulated value A in the accumulated value storing portion (step S3). Then, the set number deciding unit 25 of the SCU 7 decides whether or not the set number accumulated value A stored in the accumulated value storing portion is "1" (step S4). As a result of this decision, if it has not been decided that the set number accumulated value A is "1", i.e., if any address set abnormality has occurred in the past, the set number deciding unit 25 then decides whether or not the set number accumulated value A is less than or equal to 2 or is more than or equal to 3 (step S12). As a result of this decision in step S12, if the set number accumulated value A is less than or equal to 2, the reset signal generator 27 of the SCU 7 then generates the reset signal. Based on the reset signal, the stored contents in the buffer memories 11 are cleared, and own addresses of own station stored in their own address storing areas 17 of the address/flag memorie, 21 are set to a predetermined address, e.g., "00", etc. which is common to all communication stations 3, and then write enable/disable states of own addresses stored in the lock flag (LF) storing areas 19 are initialized to the write enable state (LF=0) (step S13). After the initialization in step S13, the processes in step S5 and forth are executed sequentially. In contrast, as a result of the decision in step S12, if the set number accumulated value A is more than or equal to 3, the reset signal generator 27 of the SCU 7 then recognizes the effect that the bet number accumulated value A has reached the re-set upper limit value. Then, abnormal termination of the address set process is performed (step S14). In this way, according to the address setting method according to the present invention, the communication station whose own address coincides with the destination address of the communication data received via the data transmission line and whose write enable/disable state of own address stored in a state storing means is in its write enable state can update its own address to the variably set address value described in the variably set address description area of the communication data, then update its write enable/disable state of its own address to the write disable state, then executes predetermined calculations for the variably set address value described in the variably set address description area of the communication data, then describes the variably set address value calculated by this calculation in the variably set address description area of the communication data, and then transmits the communication data whose variably set address value has been rewritten to the next station so as to circulate between the plurality of communication stations sequentially. Therefore, their own addresses can be set to a plurality of communication stations by simple process procedures respectively and also throughput as a whole communication system upon setting the address can be improved. The present invention is not limited to the example in the above embodiments and also may be implemented as appropriately modified within the claims. In other words, tor instance, in the present embodiment, the case has been illustrated where the SCU which can manage integratedly the own address allocation/set process for the plurality of communication stations respectively is connected to any one communication station. However, the present invention is not limited to this embodiment only and the communication system according to the present invention can be constructed by installing the address setting/managing function, which is carried out by the SCU, as any one of functions of the communication station. Furthermore, if the communication system is constructed such that a total number of the communication stations can be registered previously in the SCU, and then the SCU can collate the total number of the registered communication stations with the variably set address value described in the variably set address description area in the communication data being returned to the own station when the communication data have returned the original SCU after they have circulated in the communication system, it can be easily checked whether or not their own addresses have been allocated/set without omission to all communication stations. Finally, if the communication system is constructed such that the SCU can retrieve the communication station whose write enable/disable of own address stored in a state storing means is its write enable state, the number of the communication stations in which their own addresses are not set yet can be grasped.

Claims: An address setting method which is used in a communication system (1) constructed by connecting a plurality of communication stations (3) mutually via data transmission lines (5) in a data exchangeable manner and allocates/sets their own addresses by circulating sequentially communication data (31) between the plurality of communication stations (3) so as to enable mutual discrimination of their identity, wherein when own address allocating/setting process for each of the plurality of communication stations (3) constituting the communication system (1) is started, the plurality of communication stations (3) initialize their own addresses stored in their own address storing means (17) provided in the plurality of communication stations (3) respectively to a predetermined value which is common to the plurality of communication stations (3), and also initialize their own address write enable/disable states stored in their state storing means (19) provided in the plurality of communication stations (3) respectively to their write enable states, and a system control means (7), which is connected to one communication station (3) of the plurality of communication stations (3) and manages integratedly their own address allocating/setting processes of the plurality of communication stations (3) respectively, transmits the communication data (31),in which the predetermined value, which is common to the plurality of communication stations (3),is described in its destination address portion (33),in which a destination address of the communication station (3) as a destination of the communication data (31) is described, and also in which a variably set address as any initial value is described in a variably set address description area (37) in which the variably set address to be allocated/set to the plurality of communication stations (3) respectively is described, to said one communication station (3) before being transmitted further to a succeeding communication station (3) of the plurality of communication stations (3), when their own addresses coincide with the destination address of the communication data received via the data transmission line (5) and their write enable/disable states of their own addresses stored in the state storing means (19) are in their write enable states, the plurality of communication stations (3) including the one of the plurality of communication stations (3) update their own addresses stored in the own address storing means (17) to the variably set address value described in the variably set address description area (37) of the communication data (31), then update their own address write enable/disable states to their write disable states, then execute predetermined calculations for the variably set address value described in the variably set address description area (37) of the communication data (31), then describe the variably set address value calculated by the calculations in the variably set address description area (37) of the communication data (31), and then transmit the communication data (31) whose variably set address value has been rewritten to succeeding stations (3), characterized in that the variably set address (37) and a source address (35) of the communication data (31) are initially set to the predetermined value, when their own addresses coincide with the destination address of received communication data (31) and their write enable/disable states of their own addresses stored in the state storing means (19) are in their write disable states, the plurality of communication stations (3) including the one of the plurality of communication stations (3) decide whether or not their own addresses coincide with the source address (35) contained in the communication data (31), and then when their own addresses and the source address coincide with each other as a result of coincidence decision, the plurality of communication stations (3) including the one of the plurality of communication stations (3) recognize the effect that the address setting process has been normally completed and also transmit the normally set complete signal including the effect that the address setting process has been normally completed to the system control means (7). The address setting method according to claim 1, wherein, upon receiving the normally set complete signal, the system control means (7) terminates their own address allocating/setting processes of the plurality of communication stations (3) respectively. The address setting method according to claim 1, wherein, when their own addresses and the source address do not coincide with each other as a result of coincidence decision, the plurality of communication stations (3) including the one of the plurality of communication stations (3) recognize the effect that the address setting failure has been caused and also transmit the set failure generation signal including the affect that the address setting failure has been caused to the system control means (7). The address setting method according to claim 3, wherein, upon receiving the set failure generation signal, the system control means (7) executes repeatedly their own address allocating/setting processes of the plurality of communication stations (3) respectively. The address setting method according to claim 4, wherein the system control means (7) executes abnormal termination of their own address allocating/setting processes when the repeatedly execution number of their own address allocating/setting processes reaches to a predetermined value. A communication system (1) which is constructed by connecting a plurality of communication stations (3) mutually via data transmission lines (5) in a data exchangeable manner and to which an address setting method of allocating/setting their own address to the plurality of communication stations (3) respectively by circulating sequentially communication data (31) between the plurality of communication stations (3) so as to enable mutual discrimination of their identity, wherein the communication data (31) comprises, a destination address area (33)in which destination addresses of the communication stations (3) as destinations of the communication data (31) are described, and a variably set address description area (37) in which variably set addresses to be allocated/set to the plurality of communication stations (3) respectively are described, and each of the plurality of communication stations (3) comprises, an own address storing means (17) for storing its own address of own communication station (3), a state storing means (19) for storing its write enable/disable state of its own address stored in the own address storing means (17),and an initializing means (15) for initializing its own address which is stored in the own address storing means (17) provided in the plurality of communication stations (3) respectively to a predetermined value which is common to the plurality of communication stations (3), and also initializing its own address write enable/disable state stored in the state storing means (19) provided in the plurality of communication stations (3) respectively to its write enable state, when their own address allocating/setting processes for the plurality of communication stations (3) constituting the communication system (1) respectively are started, and a system control means (7) which is connected to communication station (3) of the plurality of communication stations (3) and manages integratedly their own address allocating/setting processes of the plurality of communication station (3) respectively comprises, an initial data transmitting means (9) for transmitting the communication data, (31) in which the predetermined value which is common to the plurality of communication stations (3) is described in the destination address portion (33) and also in which a variably set address as any initial value is described in the variably set address description area (37), to said one communication station (3) of the plurality of communication stations (3) including its own communication station (3), before transmitted further to a succeeding communication station (3) of the plurality of communication stations (3), the plurality of communication stations (3) including the one of the plurality of communication stations (3) comprises, a communication data receiving means (9) for receiving the communication data (31) via the data transmission line (5), an updating means (13) for updating their own addresses stored in the own address storing means (17) to the variably set address value described in the variably set address description area (37) of the communication data (31),then updating their own addresses write enable/disable states stored in the state storing means (19) to their write disable states, when their own addresses coincide with the destination address of the communication data (31) received via the data transmission line (5) and their write enable/disable states of their own addresses stored in the state storing means (19) are in their write enable states, and a communication data transmitting means (9, 11, 23)for executing predetermined calculations for the variably set address value described in the variably set address description area (37) of the communication data (31), then describing the variably set address value calculated by the calculations in the variably set address description area (37) of the communications data (31), and then transmitting the communication data (31) whose variably set address value has been rewritten to succeeding stations (3), characterized in that the variably set address (37) and a source address (35) are initially set to the predetermined value, when their own addresses coincide with the destination address of received communication data (31) and their write enable/disable states of their own addresses stored in the state storing means (19) are in their write disable states, the plurality of communication stations (3) including the one of the plurality of communication stations (3) is adapted to decide whether or not their own addresses coincide with the source address (35) contained in the communication data (31), and then when their own addresses and the source address coincide with each other as a result of coincidence decision, the plurality of communication stations (3) including the one of the plurality of communication stations (3) is adapted to recognize the effect that the address setting process has been normally completed and is also adapted to transmit the normally set complete signal including the effect that the address setting process has been normally completed to the system control means (7). The communication system (1) according to claim 6, wherein one communication station (3) of the plurality of communication stations (3) comprises, an initial data transmitting means (9) for transmitting the communication data (31) in which the predetermined value which is common to the plurality of communication stations (3) is described in the destination address portion (33) and also in which a variably set address as the initial value is described in the variably set address description area (37) to the succeeding communication station (3) of the plurality of communication stations (3) including its own communication station (3).

Inventors: NAKATSUGAWA YOSHINORI, NAKATSUGAWA, YOSHINORI
Applicants: YAZAKI CORP, YAZAKI CORPORATION
Application year: 1998
Main classification: H04L29
IPC codes: H04L12, H04L29