DE10145518A1 - Method for introducing redundancy mechanisms into a communications system uses disjunctive paths to transmit a data telegram to nodes for synchronizing a beat in a signal pulse. - Google Patents

Abstract

A data telegram for synchronizing a beat in a signal pulse is transmitted to nodes via disjunctive paths. If transmission is interrupted in one of the disjunctive paths, the data telegram is transmitted by the signal pulse beat via a first dividing path in an interrupted path and also transmitted by the signal pulse beat via a non-interrupted path and from there via a second dividing path in the interrupted path. Independent claims are also included for a system for carrying out the method of the present invention and for a computer program product with computer-readable devices for carrying out the method of the present invention.

Description

The invention relates to a system and method for insertion Redundancy mechanisms in a communication system.

DE 42 15 380 A1 describes a method for synchronizing known from local timers of an automation system. In this procedure, a local timer is used with a Time information synchronized from the time information of a central timer and one of the transmission and Processing time corresponding correction is formed. The Time information is supplied by a central timer appropriate transmission unit only if this from the current time by less than a predetermined amount wear differs. A disadvantage of this known method is that if there is a failure of the central timer comes or when the bus line to the central timer broken, no synchronization of the local timers more can be done.

DE 197 03 963 A1 describes a replacement method of data between decentralized electronic construction known groups. An assembly is used as a clock generator used and without a redundancy mechanism.

Various standardized are from the prior art Communication systems, also called bus systems, for data output exchange between two or more electronic assemblies or devices known, especially for use in Automation systems. Examples of such communications on systems are: Fieldbus, Profibus, Ethernet, Industrial Ethernet, FireWire or internal PC bus systems (PCI).  

These bus systems are each for different applications fields of application are designed or optimized and allow for construction of a decentralized control system. For process control and monitoring in automated manufacturing and esp especially with digital drive technologies are very fast and reliable communication systems with predictable re Action times required.

With parallel bus systems, such as SMP, ISA, PCI or VME, is a very quick and easy communication buildable between different assemblies. These well-known Bus systems are used in particular in Rech and PCs.

In particular from automation technology, synchronous, clocked communication systems with equidistance properties known. This is a system made up of at least two Participants who use a data network for the purpose of mutual exchange of data or mutual transfer of data are interconnected. This is where the Da takes place cyclical exchange in equidistant communication cycles, by the communication clock used by the system are given. Participants are, for example, central car Automation devices, programming, project planning or Be service devices, peripheral devices such. B. I / O Assemblies, drives, actuators, sensors, memory programming bare controls (PLC) or other control units, compu ter, or machines that exchange electronic data with other ma Exchange machines, especially data from other machines to process. The following reg Understand ler or control units of any kind.

An equidistant deterministic cyclic data exchange in communication systems is based on a common clock or time base of all compos involved in the communication  components. The time base is marked by one component (beat) to the other components transfer. With an isochronous real-time Ethernet, the Clock or the time base of a synchronization master specified by sending synchronization telegrams. In the event of a component failure of a racquet or a ver binding path of the racquet falls the beat or Zeitba sis for the remaining comms involved in the communication components. The object of the invention is the loss of Clock or time base for the rest of the communication prevent components involved.

The problem underlying the invention is with the Features of the independent claims solved in each case.

Preferred embodiments of the invention are in the depend given claims. After a first preferred Embodiment of the invention becomes a redundancy mechanism for clock synchronization so that one Beat the clock is transmitted on disjoint paths. This principle can be used when using only one clock racket as well as when using multiple bats be turned. If there is an interruption in one of the Paths, so the corresponding data telegrams of the clock racket in the resulting from the interruption Subnets fed.

According to a further preferred embodiment of the invention a redundancy mechanism is introduced in which several Bat each with different priority in the Communication system are in place. The synchronizes Beats with the highest priority also everyone else Beats so that the clock signals from beats and of replacement bats in normal operation almost identical are.  

If the top priority beat fails, automa table the available bat with the next one lower priority than beats for a particular Node selected in the communication system. This selection can be done in such a way that in each data telegram one cycle racket whose priority is included. Based on A node in the communication system, select the data telegram of the highest priority beat. The priorities can be fixed or the Priorities may be in the event of a clock failure rackets will be reassigned.

For example, the selection of a replacement clockbeater can be used a failure of the top priority beat over a ent speaking configuration of the communication system. It is particularly advantageous if the beats via In information about the existing or projected in the system Beats can have so that prioritization at for example via the configuration.

In the nodes of the communication system to be synchronized will only ever use the highest priority clock signal det which is available at the node concerned, or one of several or all at one node is available Ren clock signals generated weighted clock signal. The Ge weighting can be achieved by averaging the individual clock signals nale or generated by another type of filtering the.

The invention allows the introduction of a redundancy mechanism mus in a communication system by means of simultaneous Using multiple bats or using a mechanism must be used to activate spare beats in the event of a fault case. The one with the invention is particularly advantageous achievable increase in the availability of such systems because  the failure of a single component (bat) or a connection path does not lead to failure of the overall system leads.

This advantage according to the invention is particularly in the case of an application for packaging machines, presses, plastic injection machines, textile machines, printing machines, machine tools robots, handling systems, wood processing machines, Glass processing machines, ceramic processing machines like that like hoists of importance.

Preferred embodiments of the invention are described below dung explained with reference to the drawings. It demonstrate:

Fig. 1 is a block diagram of a first embodiment according to the invention egg nes communication system,

Fig. 2 is a flow diagram of a first embodiment of the method according to the invention,

Fig. 3 is a block diagram of a second preferred exporting approximate shape of a communications system according to the invention with at least one spare clock pulse,

Fig. 4 is a flow diagram of a second embodiment of the method according to the invention with at least one spare clock pulse,

Fig. 5 is a flowchart of a further embodiment of the method according to the invention with an alternate cycle.

Fig. 1 shows an embodiment of a communication system according to the invention to the nodes 1 to 5. Each of the nodes 1 to 5 contains a device component of the communication network, such as a clock or a control unit. In the example shown, the component of the node 1 is a clock which generates data telegrams for the synchronization of the components of the further nodes 2 to 5 . These data telegrams are transmitted via lines 6 to 10 , which connect the individual nodes 1 to 5 to one another, in the communication system.

The transmission of a data telegram from node 1 takes place on the one hand via a path P ₁ , which includes lines 6 and 7 , to nodes 2 and 3 . The nodes 2 and 3 form an M ₁ , which belongs to the path P ₁ .

On the other hand, the data telegrams are transmitted to nodes 4 and 5 via lines 8 and 9 . Furthermore, the nodes 3 and 4 are connected to one another via a line 10 . The lines 8 , 9 and 10 form a path P ₂ , to which the set M ₂ of nodes 4 and 5 belongs.

The two paths P ₁ and P ₂ are connected to one another at their end points by the line 10 of the path P ₂ . Due to the resulting ring topology, each of the nodes 2 to 5 can receive both the data telegram sent by the beat of the node 1 via the path P ₁ and the path P ₂ .

The relevant component in a node can then only use that data telegram for synchronization, which has been sent out via the path to which the relevant component belongs - in the case of node 2 , this means that the component of node 2 only has the Da evaluates the telegram of the beat of node 1 , which has been received via line 6 .

On the other hand, it is also possible that one component has both Da tent telegrams, that is, both the data telegram of the Path to which the component belongs, as well as the data tele gram of the other path, used for synchronization, for example by using one of the two data messages for the synchronization weighted or filtered signal gene is riert.

For the component of node 2 , this means that both the data telegram received by line 6 and the line 7 received by component 1's racquet is used for synchronization.

In the event of a fault, an interruption occurs, for example, at the point of the network marked X in line 7 in FIG. 1, that is to say path P1 is separated between nodes 2 and 3 . This results in a partial path P ₁₁ with line 6 and node 2 and a partial path P ₁₂ with node 3 .

In this case, the nodes 2 to 5 of the communication system are supplied with data telegrams for synchronization via the sub-networks resulting in this way, that is to say the component of the node 2 receives a data telegram from the beat of the node 1 via the line 6 and the components 4 and 5 receive a data telegram via lines 8 and 9 of path P ₂ . The partial path P ₁₂ consisting of the node 3 is connected to the path P ₂ via the line 10 , so that the component of the node 3 also receives a data telegram for synchronization despite the severing of the line 7 .

The disjoint paths P ₁ and P ₂ thus ensure that the communication system can continue to work even in the event of a line cut.

Fig. 2 shows a corresponding flow chart. In normal operation of the communication system, data telegrams are transmitted from a cycle beat of the communication system via disjoint paths. The data telegrams are transmitted via path P ₁ to nodes of the communication system of set M ₁ and via path P ₂ to nodes of set M ₂ . The paths P ₁ and P ₂ are disjoint and preferably have the same end point or are connected to one another at their end points via a line.

An error occurs in step 21 . For example, path P _{1 is} interrupted by the fault. Path P ₁ thus breaks down into two sub-paths P ₁₁ and P ₁₂ . The path part P ₁₁ has a direct connection to the node of the communication system, which contains the bat. This partial path P ₁₁ has a subset M ₁₁ of nodes of the quantity M ₁ .

In contrast, the subpath P _{12 has} no direct connection to the node of the communication network with the clockbeater and contains a subset M ₁₂ of nodes of the set M ₁ . However, the partial path P ₁₂ has a connection with the path P ₂ .

In step 22 , the beat rack transmits a data telegram via subpath P ₁₁ to the nodes of set M ₁₁ . By cutting the path P ₁ results in a chained path P _ver , which consists of the interconnected paths P ₂ and P ₁₂ be. The clockbeater transmits the corresponding data telegram to the nodes of the combination set of the quantities M ₂ and M ₁₂ via this linked path. The resulting paths P ₁₁ and P _ver are also disjoint, but do not have a common end point or a connection between their end points.

Fig. 3 shows an alternative embodiment of he inventive communication system. The Kommunikationssys system of FIG. 3 11 includes the node to 15, the obligations over Lei 16 are connected to each other through 19. In at least two different nodes of the communication system there is a beat rack; in the example of FIG. 3 is the nodes 11 and 15.

The nodes 11 and 15 beats have different priorities. For example, the beat of node 11 is the highest priority beat and the beat of node 15 is a lower priority beat, which is also referred to as a spare beat.

In normal operation, both the clock beat of node 11 and the spare clock beat of node 15 are active and send corresponding data telegrams. The priority is a property of the respective bat and is statically defined when the communication system is parameterized and / or can be dynamically adapted to the respective situation. The respective priority is known to the components to be synchronized and / or is transmitted together with the data telegram of the clock signal. All components use only the clock signal of the highest priority, including the spare clock bat or bats for their synchronization with the highest priority beater.

In normal operation of the communication system of FIG. 3, the beats of nodes 11 and 15 each send data telegrams for synchronization. The respective data telegrams contain an identifier from which the priority of the beat rack that sent the data telegram results.

The components in nodes 12 , 13 and 14 each receive two data telegrams with different priorities, which result from the respective identifier contained in the data telegram. The component in question can then select the data telegram from the higher-priority beater and only use this for synchronization. However, the component can also take both data telegrams into account and generate a signal for the synchronization of the local clock signal of the component by filtering, for example weighting the corresponding synchronization data.

In a first fault, for example, the beat fails in node 11 . In this case, the synchronizing components of the nodes 12 , 13 and 14 only receive data telegrams for the synchronization of the substitute clockbeater of the node 15 , which due to the failure of the clockbeater of the node 11 is also the remaining clockbeater of the communication system and is therefore of the highest priority Beat becomes. Because of this, the replacement beater takes the place of the failed beater.

With a weighting of the individual data telegrams of the clockbeater and the spare clockbeater, in the event of a failure one of the clockbeat algorithms using past values can be used to adapt the clock or time base of the component in question to the clock signal of the remaining spare clockbeater without a jump. Such an algorithm can also be used to sever the communication system, e.g. B. be used at the location marked X in FIG. 3 if only the clock signal of the main clockbeater or the clock signal of the spare clockbeater is then received in the individual components.

For example, if the system is interrupted at point X, e.g. B. by a cable break, the network "breaks up" into two subnets. However, the components within the subnetworks are still synchronous on the basis of the data telegram received in each case from one of the clock beats of nodes 11 and 15 .

In a further preferred embodiment of the communication system of FIG. 3, only the highest priority clockbeater sends in normal operation, that is, the clockbeater of the node 11 . The data signals sent by the beat of node 11 are also received by the spare beat of node 15 .

If the beat of node 11 fails, the substitute beat in node 15 no longer receives a clock signal. After a configurable number of communication cycles, the spare clockbeater of the node 15 then starts operating and sends data telegrams for synchronization to the components of the network to be synchronized.

The cycles between the failure of the highest priority clockbeater of the node 11 until the start of operation by the replacement clockbeater of the node 15 are bridged by the internal clock generation in the components. The transition from the synchronization by means of the data telegrams received from the master clockbeater to a synchronization based on data telegrams from the substitute clockbeater or from the internal clock to the clock of the substitute clockbeater is controlled or regulated by algorithms using historical values without a jump.

The same applies to an interruption of the system, e.g. B. at the point marked with X in FIG. 3. In advance, both beaters are still active in such a line break, the network in turn breaks down into two subnetworks, each of which is synchronized by means of the main or spare clock beater.

FIG. 4 shows a flow diagram of another exporting approximate shape of the inventive method. Step 40 concerns normal operation. Several clock beaters T ₁ to T _n each send data telegrams to the network.

The individual beaters have different priorities, which means that each priority only occurs once in the communication system. For example, the racquet T ₁ is the racquet with the highest priority and the racquet T _n is the racquet with the lowest priority, the priorities of the racquets T ₂ to T _n-1, for example, decreasing linearly with their running index are.

The individual data telegrams of the beaters contain an identifier from which the priority of the corresponding beater can be recognized for each node in the communication system. For example, each node only takes into account the data telegram originating from the highest priority cycle clock T ₁ for the synchronization. This also applies in particular to the low-priority beaters T ₂ to T _n , which in turn synchronize themselves with the highest-priority beater T ₁ by means of its data telegrams.

In step 41 there is a failure of the highest priority clock T ₁ due to a defect in the clock T ₁ and / or a line break that disconnects the clock T ₁ from at least some of the nodes of the communication system.

In the following, such an arbitrary node K _{i is} considered, which no longer receives the data telegrams from the clock beat T ₁ . In step 42 , the node K _i first checks whether there is a receipt of data telegrams from the clockbeater with the next lower priority, that is to say from the clockbeater T ₂ . If this is the case, this beater T _{2 is selected} by the node K _i in step 43 as a beater for the further synchronization.

If this is not the case, in the subsequent step 44 it is checked in each case for beats T _j in order of decreasing priorities by the node K _i whether a data message can be received from the beats T _{j in} question. If this is the case, the clock beat T _j in question is selected in step 45 for the further synchronization.

If the opposite is the case, it is finally checked in step 46 with regard to the clock pulse T _n with the lowest priority whether a data telegram can be received in the node K _i from this lowest priority clock pulse T _n . If this is the case, this beat is selected in step 47 by the node K _i for further synchronization. If the opposite is the case, the failure of the node K _{i in question is} reported in step 48 , in which, for example, a signal lamp comes on.

Depending on the type of accident, the tests 42 and 46 in the nodes of the communication system can result in different results for the nodes in question, that is, a different selection of beats. For example, the communication network can break down into subnetworks due to one or more line interruptions, which are then supplied by different spare clock beats of different priority. It is particularly advantageous that the selection of replacement clock beats is made centrally in the individual nodes.

FIG. 5 shows a flow diagram of another preferred embodiment of the method according to the invention. Step 50 relates to normal operation. In normal operation, only one of the beaters, that is, the highest priority beater, for example beater T ₁ , sends data telegrams for the synchronization of components in the network of the communication system.

In the communication system there are further beaters T ₂ to T _n , each of which has a decreasing priority from T ₂ to T _n . These spare clock beaters receive the data telegrams from the highest priority clock beater T ₁ as well as the other components of the communication system in the nodes of the network. However, in normal operation, the replacement clock beaters do not send any data telegrams for synchronization.

Also in normal operation, the components of the nodes of the network use the data telegram from the highest priority clock beat T ₁ for the synchronization of the corresponding local clock signal in step 51 . This also applies to the spare beats that keep their respective internal oscillator in sync with that of the main beater T ₁ .

In step 52 , a malfunction occurs in that the clock fails due to a defect and / or a line break for at least some of the nodes in the network.

A replacement clock beat must then be activated for the relevant nodes in the network. In step 53, a clock beat T _j checks from the set of spare clock beats T ₂ to T _n whether it receives a data telegram from a higher priority spare beat beater after no more data telegram has been received from the main clock beat T ₁ after a dead time. If this is the case, the racquet T _j uses the data telegram from the higher-priority racquet for the synchronization of its internal oscillator in step 54 .

If, however, the beater T _j cannot receive a data telegram from a higher-priority beater after a certain dead time, then this beater T _j activates itself automatically in step 55 by sending data telegrams for synchronization. This clock beat T _j then serves at least for a sub-network as a spare clock beat for synchronization.

If the network has broken down into different subnetworks, different substitute clock beats may result for the different subnetworks on the basis of the test in step 53 . It is of particular advantage that the test in the individual replacement cycle beaters is decentralized, which gives maximum flexibility in terms of failure redundancy.

In summary, the invention is a system and method for introducing redundancy mechanisms in a communication system with the following steps:

• a) Transmission of a data telegram for the synchro nization of a beater via disjunct Pfa de to the nodes,
• b) in the event of an interruption of transmission in one of the disjoint paths:
  • a) transmission of the data telegram from the clockbeater over a first partial path of the interrupted path and
  • b) transmission of the data telegram from the clockbeater via the uninterrupted path and from there via a second partial path of the interrupted path.

This is also a syn Chronization of nodes of a communication system, esp special of an automation system, as well as a of the computer program and system.

Claims (14)

1. Procedure for the synchronization of nodes ( 1-5 ) of a communication system with the following steps:

• a) transmission of a data telegram for synchronization from a beat by disjoint paths ( 6 ) to the nodes ( 1-5 ),
• b) in the event of an interruption of transmission in one of the disjoint paths:
  • a) transmission of the data telegram from the clockbeater over a first partial path of the interrupted path and
  • b) transmission of the data telegram from the clockbeater via the uninterrupted path and from there via a second partial path of the interrupted path.

2. Procedure for synchronizing nodes ( 1-5 ) of a communication system with the following steps:

• a) transmission of a data telegram for synchronization from a top priority beat to the nodes ( 1-5 ),
• b) in the event that a low-priority bat does not receive a data telegram from a higher-priority bat: transmission of a data telegram for synchronization from the low-priority clock to at least a subset of the nodes ( 1-5 ).

3. Procedure for synchronizing nodes ( 1-5 ) of a communication system with the following steps:

• a) transmission of data telegrams for the synchronization of at least two beats under different priority to the nodes ( 1-5 ),
• b) Selection of the data telegram from a top priority beat from the data telegrams received from a node ( 1-5 ).

4. The method according to any one of claims 1, 2 or 3, in which the highest priority bat all syn syn chronized. 5. The method according to any one of the preceding claims 1 to 4, where the data for synchronization in the data tele gram the beats of different priority in the we are substantially identical. 6. The method according to any one of the preceding claims 1 to 5, where each data telegram is the priority of the beat contains that sent the data telegram. 7. The method according to any one of the preceding claims 1 to 6, in which when choosing a top priority beat the Beats with the next lower priority automatically becomes the top priority beater. 8. The method of claim 7, wherein a priority identifier of the bat with the next lower priority increased becomes.   9. The method according to any one of the preceding claims 1 to 8, in which each of the data telegrams contains a priority identifier of the corresponding clock and the selection of a highest priority clock in a node ( 1-5 ) is based on the priority identifiers. 10. The method according to any one of the preceding claims in the the beater information about the existing in the system receive or planned beats and / or themselves can procure yourself. 11. The method according to any one of the preceding claims, in which at least a selection and prioritization of the beats once when the system is started up, and / or that prioritizing the bats in particular done via a configuration. 12. The method according to any one of the preceding claims, in which either the highest priority clock signal or a signal weighted from all clock signals is used. 13. System for carrying out a method according to one or several of claims 1 to 12. 14. Computer program product with computer-readable means for Carrying out a method according to one or more of the Claims 1 to 12 if the computer program in a commu nication system is running.