Method and arrangement for the decentralized transfer of the master function in multicomputer systems with a looped transmission channel.

p0001The invention relates to a method and a Vorichtung to transfer the master role in multiprocessor systems with annular transmission channel, in which     Subscriber stations are connected in series to one another via a unidirectional transmission channel and in each case a receiving and transmission means as well as a between receiving and transmitting means by way of the transmission channel which is arranged the transmission channel interrupting and closing switching means comprise the transmission channel during the transmission of useful data only interrupts the switching devices of the current master station .     change through all other subscriber stations during data transmission, the received signals immediately on its transmission facilities     and     the transfer of the master function is caused by sent by the current master station control signals.

p0002For data transfer between system components of a multi-computer system for process data processing, process and laboratory automation, office communication, among others are known parallel and serial transmission method. In hierarchical, decentralized spatially distributed systems to enable primarily used serial transmission systems for reasons of data security, flexibility and at the shortest possible transmission routes.

p0003Depending on the type of access control of subscriber stations in a serial communication channel are controlled allocation and random allocation, according to the place of allocation centralized and decentralized allocation, after the request time interval the fixed and the free allocation and by the selection rules for the next allocation static priority procedures fair allocation and sequential allocation distinguished. Especially for process automation systems with hierarchical intelligent user stations, the messages among themselves to exchange whilst respecting a strictly defined response time to alarms and messages, so only methods with decentralized allocation and Wi possible request time frame come into question.

p0004The simplest, redundant topological structure with fault tolerance features for connecting multiple participants the ring or multiple ring structure known (sua US Patent 4,486,852, US Patent 4,495,617, US Patent No. 4,501,021, DE-OS 3 150 474, DE-OS 3012105 and DD-PS 225 293 and Heger / Steusloff / Syrbe: real-time computer system with distributed microprocessors, the Fraunhofer Institute for information and data processing, Karlsruhe 1979, Dyer: rtp seminar bus systems, R. Oldenbourg Verlag , Munich / Vienna, 1984).

p0005Typical locally controlled access methods are, inter alia, the slot operations in which circulate on the ring sections, are enrolled in by the sender messages that are deleted by the receiver and the tab insertion ring in which a transmitting station wishing a message telegram between two on the ring located telegrams inserts, while caches the subsequent message and sends only after their own. A disadvantage is the little flexible response to different and changing load conditions at slot method with respect to the messages attack the stations, since a large part of the channel capacity can be bound by empty slots and the high cost of caching and protection against failures at the register insertion ring. Another typical decentralized controlled Zugriffsverfah reindeer is the indicator method (token - passing), in which by means of a special message, called tokens, the token is passed from one subscriber station to the next and this then perceives the broadcasting or the token passes. Each wishing to transmit subscriber station must thereby wait for the token, this take after its recognition by Ring and retransmit after submitting its data telegram the token. Advantages of the Plate method are its simplicity, the distributed access control and the independence of the message length. A disadvantage is the necessary intermediate storage associated with the recognition of the token in each subscriber station, whereby the transmission power of the transmission channel is reduced.

p0006In the EP patent 0054077 and advanced in DE-OS 3,413,473 solutions are disclosed, the indicator method more precise and have particular advantages in terms of a higher transfer efficiency. In DE-OS 3,413,473 is achieved in that the flag of two different characters, a tone and a busy signal, wherein a broadcasting rights perceiving subscriber station converts the dial tone after his capture in the busy signal and this sends out before the payload , This produces in each subscriber station between acquisition and transmission of control signals a delay that is determined by the bit positions in which the two signals are different. Another drawback is the concentration of certain functions in a particularly excellent monitor station, thereby improving the reliability of the entire transmission ring is essentially the failure behavior of the monitor station dependent. While in case of failure of any of the same subscriber station, for example by simple bridging, the ring is still functioning, there is no communication in case of failure of the monitor station on the ring usually longer possible.

p0007The invention aims to remedy this. Object of the invention is to provide a method and apparatus for decentralized controlled transmission of the master function in distributed multiprocessor systems with annular transmission channel. Each subscriber station in the annular transmission channel should be completely equal and there are no monitoring station. In the between the collection and transmission of the necessary for the transfer of the master function control signals to the wishing to transmit subscriber stations no additional delay caused, and all subscriber stations to be set up exactly the same kind with respect to the control of the master transfers and fulfill the same functions. Furthermore, to take place at the same time no caching of the Master Transfer causing the control signals in the wishing to send participants be required, and receiving and sending control signals substantially.

p0008To achieve the above object, the inventive method for transmitting the master function in distributed multiprocessor systems with annular transmission channel, in which     Subscriber stations are connected in series to one another via a unidirectional transmission channel and in each case a receiving and transmission means as well as a between receiving and transmitting means by way of the transmission channel which is arranged the transmission channel interrupting and closing switching means comprise the transmission channel during the transmission of useful data only interrupts the switching devices of the current master station .     change through all other subscriber stations during data transmission, the received signals immediately on its transmission facilities     and     the transfer of the master function is caused by sent by the current master station control signals, characterized in that     three different control signals are used for transmission of the master function,     a first control signal from the current master station is transmitted immediately after a data telegram sent by this,     all subscriber stations with transmission request after receiving the first control signal transmission channel by opening its switch means to interrupt,     a light emitted from the current master station after the first control signal the second control signal, the master function is transferred to the sending Participant Station succeeding in the transmission direction, the third control signal from all wishing to transmit subscriber stations is sent after receiving the first control signal and     all subscriber stations that receive the third control signal, close their switching device.

p0009The following are the steps proposed invention are explained in more detail: During the transmission of user data through the current master switch means all other participants are closed. The annular transmission channel thus begins in the transmitter and receiver ends in the current Masters, all other participants through the information being received without intermediate storage immediately on their station and themselves are only slaves. The sent by the current master to the data telegram to the transmission channel first control signal is transmitted in the same way as the previous user data, so must be prevented by appropriate bit combination that the first control signal occurs in the payload.

p0010The reception of the first control signal leads to the interruption of the transmission channel for all stations with transmission request so that is structured during the following control phase of the transmission channel of a number of point-to-point connections between participants with transmission request and the current master, where all participants remain without transmitting request in the state described above.

p0011During the existence of the point-to-point connections between participants with open switching means are simultaneously transmitted second and third control signals to the transmission channel substantially, with only the current master second and all participants with request to send each delivering a third control signal. Here whereby the transmission channel by means of the second control signal, which reaches only in the transmission direction immediately following wishing to send participants, transfer the master role to this participant, while everyone else wishing to send participants and the current master will receive a third control signal and causes to close its switch means, again accepts the output structure, that is, begins in the now new current master and ends.

p0012The described process steps are repeated after each Nutzdatenaussendung regardless of their length, whereby the master function constantly circulates in the transmission direction in the ring-structured multicomputer system, and only the computer with the current transmission request are included in the control of the master transfers.

p0013In ring systems with very small ring around time the duration of the second control signal to a closing of the switching device of the current Masters before complete transmission of the second control signal, and thus prior to the transfer of the master function wishing to transmit to the next participant must not be greater than the duration of the third control signal, to avoid.

p0014The resulting consequence of the structural finite Round Trip Delay time difference between the end of transmission of the second control signal and the re-reception of the second and third control signal by the current master is thereby bridged, that the Master, the second control signal is constantly repeated during the first two or the first and third control signal on the transfer ring circulate.

p0015If not wishing to transmit subscriber station exists on the transmission ring, the current master station receives the light emitted from their first and second control signal itself again, so it remains current master station and, if in the meantime no renewed own transmission request is recorded, repeat the broadcast of the first and second control signal , The time between two successive transmissions of the first two control signals must be selected greater than or equal to the sum of all maturities on the transmission ring and the time length of the two signals to prevent error situations caused by the availability of a number of first and second control signals to the transmission ring might arise.

p0016It is expedient to select the bit pattern for the second and the third control signal so that the two signals in the first bit location voneinan of different, whereby the participants already receiving this bit information about their actual condition (master or slave) received during the next data transfer.

p0017The object of the above-solving apparatus for performing the method comprises an information processing unit and a control unit for controlling access to the transmission channel and is characterized in that     the receiving device is connected to a demodulator having a Nutzdatenausgang and a first, second and third control signal output, of which the Nutzdatenausgang with the information processing unit, the first control signal output to a first input of a first gate circuit,     the second control signal output to a first input of a second gate circuit     and     the third control signal output having a signal input for closing the switching means and having a first stop input of a control signal generator for the first and second control signals     are connected,     a transmission request signal output the information processing unit is connected to a second input of the first gate and to a second input of the second gate,     an output of the first gate is connected to a signal input for opening the switching means and with a starting input of a control signal transmitter for the third control signal, which lies at a first input of the transmission device,     a second input of the transmission device are connected to a serial Nutzdatenausgang the information processing unit and a third input of the transmission device to an output of the control signal generator for the first and second control signal, and a start input of the control signal generator for the first and second control signal to an output of the information processing unit for End signaling the user data transmission is connected     and     an output of the second gate is connected to a second stop input of the control signal generator for the first and second control signal and to an input of the information processing unit for signaling the start of the user data transmission.

p0018Appropriately, the demodulator of a Nutzdatendemodulator and from three parallel comparators whose outputs are respectively the Nutzdatenausgang and the first, second and third control signal output.

p0019The two stop inputs the control signal transmitter for the first and second control signal are via an OR circuit linked to one another; Stop the inputs of the signal transmitter for the second control signal are parallel at the output of the OR circuit; the output of the information processing unit is connected to end signaling of the transmission of user data with the start input of the control signal generator for the first control signal and with the second stop input the control signal transmitter for the second control signal; the two outputs of the control signal generator for the first and the second control signal are connected to end signaling of the control signal transmission at the start input of the control signal transmitter for the second control signal; and the start input of the control signal generator for the first control signal is also connected to a control signal repeater.

p0020Advantageously, the control signal repeater of a third gate with three inputs and from a timing element, wherein said control signal output of the demodulator for the first control signal via the timing element to the first input of the gate circuit, the control signal output of the demodulator for the second control signal to the second input of the gate and a feedback output of the switching device are connected to the third input of the gate.

p0021Advantageously, is connected, whose output is connected to a third input of the second gate and to a second input of a fourth gate circuit which is arranged for closing said switching means before the signal input at the first control signal output of the demodulator a timer.

p0022The operation of the circuit arrangement corresponds to the process.

p0023If the receiving device receives the first control signal, which continues to run concurrently on the ring via the closed switch means and the transmitter means is then opened via the comparator circuit for the first control signal and the first gate circuit, the switching means when at said first gate circuit already an internal transmission request signal is applied from the information processing unit. a third control signal to the next participant is then the signal generator for the third control signal by its activation through the transmitting device sent with open switching device, which according to its recognition by the third comparator circuit includes a switching device in turn.

p0024Simultaneously with the transmission of the third control signal is either also received by the receiving means a third control signal, resulting in the closing of the switch means, added or a second control signal which via the comparator circuit for controlling the second gate. At the second gate An output signal when there is a simultaneous transmission request. The output of the second gate signal of the information processing unit to take over the master function and causes the starting of the transmission of user data.

p0025Following the transmission of user data is started from the information processing unit of the control signal generator for the first and second control signals, whereby the transmission of a first and a second plurality of control signals is carried out until either a third control signal is received, or the right to transmit perceived themselves again after receiving a second control signal becomes. The number of the first control signal following the second control signals is, as already described in the explanation of the nature of the inventive process, depending on the Round Trip Delay.

p0026If not wishing to send subscriber is present on the ring, is repeated by the current master by means of the control signal retry the transmission of the first and second control signals after a certain time, the set greater than or equal to the ring rotation time and the length of the two first control signals from the already must be reasons. In favorable embodiment of the inventive circuit arrangement is achieved by the on the receiving device received first and following second via the transmitting device itself emitted control signals used by the round robin on the control signal repeater respectively for the restart of the signal transmitter for the first and second control signal , Thereby it is ensured that after a successful Round Trip carried immediate re-transmission of the two control signals.

p0027The method and the circuit arrangement have over known technical solutions to the advantage that the control signals for the Master Transfer or parts thereof no caching, evaluation and subsequent altered or unaltered retransmission require by the participants. Rather passes through the first control signal, which announces the transfer of the master function, without delay, all participants, and the participants wishing to transmit send regardless of what they received, at the same time a third control signal.

p0028has reached the invention with the decentralization of the transmission of the master function in addition to the advantages with respect to securing reliability of such systems. For example, in case of failure of one participant by its simple bridging the transmission ring still functional. Also can be easily further similar subscriber stations in the already operating transmission ring insert.

p0029The inventive circuit arrangement also has the advantage that the information processing units of the participants and ensure that their software is exempt from access control and that the transfer of the master function by each participant with a relatively simple hardware is achieved.

p0030In the following the invention will be explained in more detail with reference to the drawing showing an embodiment. Show it:<ul><li>FIG. 1 is a multiprocessor system with annular structure with four participants,</li><li>FIG. 2 is a block diagram of the circuit arrangement of each subscriber station and </li><li>Fig. 3 shows the scheme of the signal sequence of the received signals (E 1 ... 4) and of the transmitted signals (S 1 ... 4) and the switch positions of the switching units (SW 1 ... 4) during the transmission of the master function.</li></ul>

p0031illustrated in Fig 1 annularly structured multicomputer system with four through a unidirectional transmission channel interconnected equal participants Stationer (short: participants 100, 200, 300, 400). acts as an application example of the invention, where a term between directly adjacent participants of each one bit length is assumed. (The numbering of the subscriber stations 100, 200, 300, 400 is arbitrary.) It is based on the drawing, the realization of the master transfers from a first subscriber (eg, 100) to a third party (eg, 300) with simultaneous transmission request of another operator (eg 400) described. Three master transfer effecting control signals are defined with the following bit combinations:<ul><li>1. control signal HHH</li><li>2. control signal LLL</li><li>3. control signal HLL</li></ul>

p0032During the transmission of user data through the current master station (eg subscriber 100) is shown in FIG. 3, the switching device (SW1) 4 of the current Masters opened and the switch means (SW2 to SW4) 4 of the other participants (eg 200, 300, 400) are closed so that on the transmitter (S1) of 3 100 1 through the current master on the transmission channel 1 transmitted user data frames ND all participants on the ring and the first subscriber 100 via the receiving device 2 (E1) are received after the round Trip Delay again.

p0033After transmission of user data, the information processing unit 6 of the current master-subscriber 100 are on their output 20 from a signal which starts the control signal generator 33 via the start input 37th Regardless of that the receiving device 2 is still receiving user data frames ND1, the first control signal is sent so immediately after the user data ND1 by the subscriber 100, which circulates in the transmission ring as the user data frames.

p0034The first control signal is received by all participants, arrives there in each of the demodulator 25 and generated at the output of the comparator 26 a signal indicative of the first gate 11 drives. It is now assumed that over their transmit request outputs 13 of the information processing unit 6 at the same time bears a transmission request signal to the first gate circuit 11 among the participants 300 and 400th These two participants open their AND gates and thus the signal inputs 15 their switching devices 4. In this way, the transmission channel in three point-to-point connections between the participants 100 and 300, 300 and 400 as well as 400 and 100 split (the switching device of not wishing to transmit subscriber (in this example 200) is closed).

p0035100 second control signals to and from subscribers 300 and 400 are then respectively the third control signal sent from subscribers. This is achieved as follows: first subscriber 100: The control signal generator 33 generates after the transmission of the first control signal at the output 35 an end signal indicative of the control signal generator 34 starts at the start input 38, which then sends the second control signal. Through the output 36 of the control signal generator 34 is started constantly new, which reach more second control signals via the transmission channel 1 to the receiving device 2 of the subscriber 300th subscriber 300 and 400: The signal at the output of the first gate signal 11 starts the control signal generator 16 which in each case generates the third control signal.

p0036The broadcast of participants 1 second control signals are identified by the comparator 27 of the subscriber 300, whereby the second gate 14 is activated and the input 24 of the information processing unit 6, the command to start the Nutzdatenaussendung is granted via their serial Nutzdatenausgang 17th At the same time, participants will have 400 and 100 respectively receive the third control signal and 12 their switching means 4 is closed via the comparators 28 and the signal inputs. In parallel, the stop inputs 31, 32 of the control signal generators 33, 34 have been activated, whereby user 100 stops emitting these signals immediately by receiving the third control signal. According to the numbered 4-bit lengths round trip time on the transmission ring was the time from the subscriber 100 to receive the user data frame to ND3 from the subscriber 300 (FIG. 3) bridged by the transmission of the second control signals.

p0037If not wishing to send participants is available in the transmission ring, the Current Master receives the first and the following second control signals to the circulation itself again. In this case, the transmission of the first two control signals must be repeated, wherein the time period t from the start of transmission until the beginning of the next following transmission of greater than or equal must be the Round Trip Delay and the length of the two signals to a simultaneous presence of a plurality of first control signals to the preventing ring.

p0038This is achieved by the control signal repeater circuit 40 after the time duration of the cyclic transmission of the second control signals via the second stop input 39 of the control signal transmitter t 34 stops and at the same time the control signal generator 33 re-starts at the start input 37th In an advantageous manner, the information for the control signal 40 from the repeater receiving the first and won the first subsequent second control signal after its circulation on the transmission ring. For this purpose, the output signal of the comparator 26 is delayed 42 by means of the timer so that it 27 is applied simultaneously with the output of the comparator in the third gate 41st About the conjunctive link with the past at the feedback output 43 of the switching device 4 feedback signal which is available at the open switching device 4, it is ensured that 40 the release of the first in the control signals is repeated only in the current master via its control signal repeater. Now assumes a subscriber the right to transmit is true, a third control signal is supplied from this, as described above, emitted that terminates over the first stop input 22 and on the stop inputs 31 and 32, the cyclic transmission of first and second control signals. Arises in the current master even a renewed request to send, it will also be prevented by the activation of the second gate 14 on the second stop input 23 of the OR circuit 30 further transmission of the first and second control signals.

p0039A great selection of bit combinations for the control signals is made possible by the above-described effect of a received second or third control signal can occur only after prior receipt of a first control signal. This function is achieved by the AND operation of the output of the comparator 28 in the fourth gate 44 and the output of the comparator 27 in the second gate 14, each with the corresponding delayed by the timer 21 output of the comparator 26th Thus, with respect to the control signals only to satisfy the condition that the bit combination of the first control signal is not allowed to occur in the Nutzdatentelegrammen, while the bit combinations of the second and third control signal are respectively selectable, making this up to a respectively different bit body can be shortened.