Abstract:
An automatic ID assigning device for LAN instruments connected in a network assigns ID numbers from a master LAN instrument to respective slave LAN instruments connecting sequentially to the master LAN instrument. A first slave LAN instrument stores, as its own self ID, an ID number supplied in an ID assignment command signal supplied from the master LAN instruments through a data line connecting ports of respective slave LAN instruments. The slave LAN instrument returns an ID assignment acknowledging signal to the master LAN instrument and connects upper and lower ports of the slave LAN instrument together. The master LAN instrument updates a connecting number table of the ports of the slave IDs upon receipt of the assignment acknowledging signals and transmits a subsequent ID assigning command signal to another slave LAN instrument through the data line and through the connected ports of slave LAN instruments to which ID numbers have already been assigned. The upper and lower ports, i.e., the input and output administrative data lines, of the slave LAN instruments to which ID numbers have not yet been assigned are not connected to each other.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a device for automatically assigning respective identification numbers to each of a plurality of instruments constituting a network. 
     DESCRIPTION OF RELATED ART 
     In assigning the identification number (which shall be hereinafter referred to simply as &#34;ID&#34;) to respective LAN instruments in the network for their mutual communication, conventionally, a dip switch or the like has been mechanically set for every instrument, one by one. However, this measure has been troublesome because respective users are required to set each ID with respect to every one of the instruments so that there arises a risk that the same ID is set for two or more instruments due to complicated management of. Further, the connection arrangement of the LAN instruments on the network cannot be acknowledged because the ID assignment is performed irrespective of the connection arrangement of the instruments. Further, there has been an automatic, systematic ID assigning system employing an RS485 communication system, in which a request of a slave instrument for an ID causes a master instrument to automatically issue the ID and assign it to the particular slave instrument. Overlapping requests for ID from a plurality of the slave instruments render retransmission signals to be adjusted by means of random numbers or the like so that the master instrument will automatically assign different ID&#39;s to each of the slave instruments. While the ID&#39;s are thus automatically assigned in the instant system, the RS485 communication system employed is of the type including a bus, and there still remains the problem that the connection of the respective instruments can not be recognized in executing the ID assignment. 
     For the ID assigning arrangement of the kind referred to, reference may be made, for example, to U.S. Pat. No. 4,849,752 to Bryant. 
     SUMMARY OF THE INVENTION 
     The present invention has been suggested in order to eliminate the foregoing problem, and its primary object is to provide an automatic ID assigning device for network instruments which allows the connecting arrangement of the LAN instruments on a network employed to be recognizable. Another object is to eliminate any transmission of unnecessary management data. 
     Still another object is to provide the device which assigns ID&#39;s to the respective LAN instruments in accordance with a detected change in the connection arrangement, so as to quickly recognize accurate arrangement of the LAN instruments. 
     According to the present invention, the above objects can be achieved by means of an automatic ID assigning device for network instruments in a LAN system for managing the whole system through exchanges of management information between respective master and slave LAN instruments in the system, in which 
     the master LAN instrument is provided with a connecting number table provided for transmitting ID assigning signals from the master LAN instrument to the slave LAN instruments through an management data line provided separately from network-use data lines, and for managing the respective slave LAN instruments connected to every port of the master LAN instrument, and with a communicating means for assigning the respective ID numbers to each of the slave LAN instruments connected, and 
     the slave LAN instruments are respectively provided for being connected in a plurality to each port of the master LAN instrument, while each of the slave LAN instruments is provided with an upper LAN instrument connecting port connectable with the management data line and with an under LAN instrument connecting port connectable with under LAN instrument management data line, each slave LAN instrument further including a control means for connecting and disconnecting the upper LAN instrument connecting port and under LAN instrument connecting port so that the management data line of the upper and under LAN instrument ports will be disconnected by the slave LAN instrument in a state of not ID-assigned yet, and ID numbers for identifying the respective slave LAN instruments will be transmitted as ID assigning command signals to the management data line, making references to the connecting number table for every port by the master LAN instrument; wherein 
     the slave LAN instruments respectively receive the ID assigning command signals and store thus received ID number as their own ID while transmitting an own ID assignment acknowledging signal through the upper LAN instrument connecting port to the master LAN instrument, the management data line of the upper and under LAN instrument connecting ports being thereby made in connected state, and 
     the master LAN instrument which has received the own ID assignment acknowledging signal from any slave LAN instrument renews the connecting number table of the port of this instrument and transmits to the management data line the further ID assigning command signal containing another ID number of identifying another slave LAN instrument, which operation being repeated to automatically assign the ID numbers to the respective slave LAN instruments. 
     Other objects and advantages of the present invention shall be made clear in following description of the invention detailed with reference to preferred embodiments shown in accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram showing schematically the arrangement of a network to which the present invention is applicable; 
     FIG. 2 is a block diagram showing an example of arrangement of a slave LAN instrument in an embodiment according to the present invention; 
     FIG. 3 is a block diagram showing a working aspect of the master LAN instrument used in association with the slave LAN instrument in the embodiment of FIG. 2; 
     FIGS. 4(a) and 4(b) are explanatory views for a working aspect of a management data packet for use with the instrument in the embodiment of FIG. 2; 
     FIGS. 5a and 5b show in a block diagram another embodiment of the master and slave LAN instruments according to the present invention; 
     FIG. 6 is an explanatory view for a working aspect of the management data packet for use in the embodiment of FIG. 5; 
     FIG. 7 is an explanatory view for another working aspect of the management data packet in the embodiment of FIG. 5; 
     FIGS. 8a and 8b show in a block diagram arrangements of respective LAN instruments in another embodiment according to the present invention; and 
     FIGS. 9a and 9b show in a block diagram arrangements of respective LAN instruments in still another embodiment according to the present invention. 
     While the present invention shall now be described with reference to the respective preferred embodiments shown in the accompanying drawings, it should be appreciated that the intention is not to limit the invention only to the embodiments shown but rather to include all alterations, modifications and equivalent arrangements possible within the scope of appended claims. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, there is shown an arrangement of a LAN (local area network) in an automatic ID assigning device according to the present invention. More specifically, the device according to the present invention comprises a master LAN instrument 1 and a plurality, four in the present instance, of slave LAN instruments 2-5 which are connected respectively in series to a port of the master LAN instrument 1 through data lines L for exclusive management use. 
     Referring to FIG. 2, further, there is shown a practical arrangement of the slave LAN instruments. In the present instance, the slave LAN instrument has an upper LAN instrument connecting port (which shall be hereinafter referred to as an &#34;upper port&#34;) U and an under LAN instrument connecting port (which shall be hereinafter referred to as an &#34;under port&#34;) D, and comprises an upper or under port connecting or disconnecting means 6, a data transmitting and receiving means 7, an ID self-setting means 8, an ID recognizing means 9 and an own ID storing means 10. The upper or under port connecting or disconnecting means 6 controls connecting and disconnecting the upper port U or the under port D. The data transmitting and receiving means 7 receives data from the upper port U and also transmits data to the upper port U. The ID self-setting means 8 is to set, when the slave LAN instrument has not yet been assigned an ID, an ID given by an ID setting command from the master LAN instrument in the ID storing means 10. The ID recognizing means 9 recognizes the not set state and the set state of the ID, controls the upper or under port connecting or disconnecting means 6, depending on the recognized state and, if in the own ID unset state, the upper and under ports are in the disconnected state but, if in the own ID set state, these ports are in the connected state. 
     FIG. 3 shows an arrangement of the master LAN instrument 1, which comprises a transmission/reception means 11 with respect to the slave LAN instruments, and a management table 12 for the slave LAN instrument composition. In a state where the composition of the slave LAN instrument could have been recognized, the slave LAN instrument is subjected to polling, and the information on the state of the slave LAN instruments is collected. In a state where the composition of the slave LAN instrument can not be recognized, a composition recognizing packet is transmitted so that the composition can be recognized. The composition state of the slave LAN instruments is managed by means of the slave LAN instrument composition management table 12. 
     
                       TABLE______________________________________CompositionNo.     Registered ID              Slave LAN Instrument Information______________________________________1       1          Port 1: ENABLE; Port 2: DISABLE; . . .2       2          Port 1: DISABLE; Port 2: ENABLE; . . .3       0          Port 1: ENABLE; Port 2: ENABLE; . . .4       0          Port 1: ENABLE; Port 2: ENABLE; . . .______________________________________ 
    
     In the above Table, there is shown the slave LAN instrument composition management table. In a system where up to four of the slave LAN instruments can be connected to one port of the master LAN instrument, the table allowing the information of up to four instruments is provided to every port. The ID numbers are set with respect to the slave LAN instruments, the connection of which appears in the tables of Composition Nos. 1-4. In the initial state, the slave LAN instruments are not recognized, and Registration ID is zero for all. As the information of the slave LAN instruments, an ENABLE or a DISABLE state or partition state at the ports of the slave LAN instruments, for example, is collected. 
     In FIG. 4, there are shown packets for the master LAN instrument to recognize the composition of the slave LAN instruments, in which (a) is an ID assigning command packet transmitted from the master LAN instrument to the slave LAN instruments, and (b) is an ID assignment acknowledging packet with respect to the command packet for carrying out the transmission from the slave LAN instrument to the master LAN instrument. Here, the master LAN instrument appoints the assigning ID numbers to transmit the ID assigning command, and the slave LAN instrument of which ID is set by this command, transmits back the ID assignment acknowledging packet to the master LAN instrument. 
     Further, the operation of the automatic ID assigning device according to the present invention shall be described in the followings. It is assumed here that, as in FIG. 1, four of the slave LAN instruments are connected to the master LAN instrument, and, in the initial state, the master LAN instrument still has not recognized any one of the slave LAN instruments. In this state, nothing is registered in the management table of the slave LAN instrument&#39;s composition, and Registered ID is all zero with respect to Composition Nos. 1-4. On the other hand, the respective slave LAN instruments are all in the state where an ID has not been set yet, so that the ID recognizing means 9 in the respective slave LAN instrument recognizes this, the upper or under port connecting or disconnecting means 6 is controlled, and the upper and under ports are placed in open state. In this state, there flows no data from the upper port to the under port, whereby the packet transmitted from the master LAN instrument is received by the first slave LAN instrument 2 but does not reach the following slave LAN instruments 3-5. 
     In the master LAN instrument, first, the smallest value ID=1 is to be set and, for this purpose, ID=1 is set to the ID assigning command shown in FIG. 4(a) and is transmitted. The slave LAN instrument 2 receives this assigning command, the self ID is set to be 1, and the ID assignment acknowledging packet as shown in FIG. 4(b) is transmitted to the master LAN instrument. Further, the ID recognizing means 9 recognizes that its own ID is set to be 1, and the upper or under port connecting or disconnecting means 6 is controlled to have the upper and under ports connected. Since, at this time, the slave LAN instruments 3-5 have not yet received the ID assigning command from the master LAN instrument 1, they are maintained in the not yet ID-set state. Upon receipt of the ID assignment acknowledging packet from the slave LAN instrument 2, the master LAN instrument 1 registers the contents of the packet in the management table 11 of the slave LAN instrument composition. 
     Next, in order to set ID=2, the master LAN instrument 1 sets this ID=2 to the ID assigning command and transmits this command. While this command is received also by the slave LAN instrument 2, the command is ignored since the slave LAN instrument 2 is already in the self ID set state. Since the slave LAN instrument 2 is in the state where the upper and under ports are mutually connected, the received command reaches the next slave LAN instrument 3. Because this slave LAN instrument 3 is in the not yet ID-set state, the received command causes the self ID to be set to &#34;2&#34; for the instrument and the slave ID assignment acknowledging packet to be transmitted to the master LAN instrument 1. Upon receipt of this packet, the master LAN instrument 1 registers Reg. ID=2 at Composition No. 2 of the management table of the slave LAN instrument composition. At this moment, other slave LAN instruments 4 and 5 are in the not yet ID-assigned state. 
     In the same manner, the master LAN instrument 1 transmits the ID assigning commands of ID=3 and ID=4, and Reg. ID=3 and ID=4 are set sequentially for the slave LAN instruments from the one closer to the master LAN instrument. Further, these ID&#39;s are registered at the management table of the slave LAN instrument composition. 
     With the above operation, the master LAN instrument recognizes the composition of the slave LAN instruments connected to its port, and is thus capable of managing them. It should be appreciated that, as the composition recognition of the slave LAN instruments is completed, the master LAN instrument enters into polling for collection of data from the slave LAN instruments so that the state and information of the connected slave LAN instruments can be constantly supervised. 
     Referring to the block diagram of FIGS. 5a and 5b showing another embodiment of the present invention, there is prepared at the master LAN instrument 100, in this embodiment, a packet in which a number with &#34;1&#34; added to the largest of the ID&#39;s of the slave LAN instruments connected at this moment, to be an addressee ID. This packet is sent periodically to all ports of the slave LAN instrument 200 through the management data line L as an ID recognition request. This slave LAN instrument 200 has a shift register 240 for receiving signals coming from the upper port, and the packet received is subjected to buffering. In a state where the ID is not recognized yet, an initial self ID is set to a number larger than the largest number of the slave LAN instruments 200, 300, . . . connectable to the master LAN instrument 100. This larger number is preserved in an ID register 220. At a comparator 250, the preserved ID in the ID register 220 is compared with the addressee ID contained in the packet held by the shift register. Here, when the addressee ID is smaller than the self ID, the latter is changed to the addressee ID, the packet is not sent to the under port, and the master LAN instrument 100 is contacted to report through the management line L that the self ID has been recognized. When the self ID and addressee ID are identical to each other, the packet is processed as one for the self instrument and is not sent to the under port. When the addressee ID is larger than the self ID, a switch 270 is controlled by a switching time controller 260 for a period adapted to the composition of the packet, and this packet is sent to the under port. 
     In FIGS. 6 and 7, there are shown arrangements of the packets taken into the shift register 240 of the slave LAN instrument 200. In a working aspect of FIG. 6, a fixed word W having a fixed packet length T includes an addressee ID 280 at several initial bits, and the packet is transmitted to the slave LAN instrument 300 of the under port of the slave LAN instrument 200, by controlling the switch 270 for a switching time adapted to the fixed packet length T. Synchronization of a word unit is performed at a start bit b1 and a stop bit b2. In another working aspect of FIG. 7, every word includes the addressee ID 280, so that the switching time of the switch 270 is controlled at every word W. 
     The foregoing master LAN instrument can transmit a broadcast signal (general simultaneous transmission signal) which can be received by all slave LAN instruments connected to the ports of the master LAN instrument. At this time, the master LAN instrument transmits an ID reset command for the slave LAN instruments with the broadcast signal upon source re-making and reset operation after source breaking. Any slave LAN instrument which has received this command is reset by an ID reset means and is caused to shift to the not ID-set state. Thereafter, the master LAN instrument starts the ID assignment to the slave LAN instruments from the initial state and newly registers the connection arrangement. 
     Referring next to a block diagram of FIG. 8 showing still another embodiment of the present invention, the master LAN instrument 100 in this embodiment is provided with a presence confirmation signal transmitting means 140, which periodically transmits a presence confirmation signal to the management data line L. The slave LAN instrument 200 includes a presence confirmation signal detecting means 206 at the upper port connected to the management data line L and recognizes the presence confirmation signal sent periodically from the master LAN instrument 100. When a timer 204 determines that the presence confirmation signal has not been received for a set term, an ID in a transmitting means 212 between the master LAN instrument and the slave LAN instruments is reset by an ID reset means 202, and this slave LAN instrument 200 shifts to the no ID-recognition state. This operation can be similarly performed in other slave LAN instruments 300 and 400. 
     Referring to a block diagram of FIG. 9 showing a still further embodiment of the present invention, the slave LAN instrument 200 in this embodiment is provided with an upper port connection monitoring means 208 connected to an ordinary network data line N separate from the management data line L. In this case, whether the data line is connected is monitored so that, when a disconnection of the upper port data line is detected, the ID at the between master-and-slaves transmitting means 212 is reset by the ID reset means 202, and the slave LAN instrument 200 shifts to the no ID-recognition state. This operation can also be performed similarly in the further slave LAN instruments 300 and 400.