DE19645861A1 - Platform independent communication process for heterogeneous networks - Google Patents

Abstract

The system has a local are network, LAN, bus that connect with two separate CAN busses 2,3. The LAN bus supports a number of programmably controllers 4,5, work stations 6 and actuators 12. The CAN busses support a range of actuators 7,10,11 and sensors 8 together with such as a lap top 9. One of the programmable controllers coordinates the units.

Description

The invention relates to the field of information processing, especially remote Process communication and relates to a method for network type and computer architecture independent transmission of information or control signals, especially between spatially distributed sensors, actuators and control computers.

According to the state of the art, there are various specially tailored fieldbus solutions such as CAN, RS-232, Profibus etc.) as de facto standards with a multitude of user interfaces established; Ethernet has largely existed at the level of the control and control computer (LAN node) enforced. Different standards for individual network types are used as transmission protocols used; a uniform protocol is not available. There are still isolated ones Cross-connections (bridges) to selected fieldbuses or between fieldbuses and LANs. However, these are not uniform among each other and only for the particular problem customized.

Rerouting mechanisms for the purpose of failover by automatic switching to redundant transmission media and / or information nodes are currently based exclusively on software and / or hardware tailored to the specific network combination or application solutions.

Prior art systems are not real heterogeneous networks because there are no universal bridges between the named network types; There is none uniform cross-network user interface.

In particular, there is no real-time capable distributed operating system based on the field buses and LANs.

Once installed, networks are self-contained and therefore not prepared for expansions other network types; a complete network changeover or complex network renewal is the result. For every integration of a new network, the user must be familiar with deal with the manufacturer-related physical transmission protocol and its applications adapt accordingly; this is extremely time consuming and costly.

It was therefore an object of the invention, the difficulties and disadvantages that are in the prior art Show technology, eliminate and a heterogeneous network system with a uniform user to provide an interface which is essentially the simple implementation of distributed real current operating systems supported.

This object is achieved according to the invention by those in the characterizing part of the patent claims 1 mentioned features.

Above all, the method according to the invention permits the creation of an application on the basis a virtual network, this application on all network types of integration platform is functional without adaptation and reprogramming.

The very time-consuming preoccupation with the physical conditions of the respective over carrier medium is eliminated; the user uses a distributed real-time operating system. Solutions created on this basis are open to future, technologically new networks types. Due to the implemented multi-master network structure, the system behaves incorrectly tolerant; the functions of failed information nodes can depend on redundant functions other information nodes can be realized.  

The invention works in the following way.

Parameters run on each information node according to the specification of program modules controlled functions that generally belong to the software application and for example control purposes, the acquisition of measured values or information processing to serve.

Communication is established in this heterogeneous network by either each of these functions unidirectionally and any other adjacent function passes parameters asynchronously and thus controls them.

For this purpose, the function in question generates a data packet (e.g. control variables, measured values tend), which is identified by a logical address. The logical address consists of logical network, logical communication partner and logical channel and defined thus a virtual target function as a black box.

The data packet has a globally uniform data format, which is only from the virtual Target function (i.e. from the logical channel), but not from the logical network or platform of the logical communication partner.

The logical address of the generated data packet is gradually created using mapping tables resolved.

Using a transmission media assignment table, the logical network is connected to the Start information node assigned to connected physical transmission medium, still is based on a node assignment table valid for this medium the logical com communication partner a physical address of a connected to this transmission medium Information node determined. The data packet is made in accordance with the transmission media specific modules (program-controlled and / or hardware-supported) to this target information mation node sent; there the logical is based on a function assignment table Channel assigned a function and the received data packet as a function of this function pass meter.

Functions which are controlled by parameters addressed to them can be referred to Control other functions in a parametric manner; it is a continuous one Communication process possible.

Data packets can only be sent directly via exactly one physical transmission medium are addressed and sent to information nodes connected to this medium. Including parameter-controlled functions, which the assigned parameters preferably as an unchanged data packet to another virtual function with new logical addresses functions can gradually move topologically more distant functions in the heterogeneous network being controlled. Consequently, the special case of a bridge, its Destination essentially through the content of the assignment tables of start, bridge and destination information mation node is determined.

It is essential that all the assignment tables mentioned (transmission media, node and Function mapping tables) are information node specific, d. H. that they are only valid the respective information node on which it is stored locally non-volatile locally are; the node assignment tables are also transmission medium-specific. The An administrator can create these assignment tables using tools in at least one initialization process, at least for each specific configuration of a heterogeneous network.

Furthermore, each node mapping table can have its own physical address Information node on which it is stored locally with logical communication partners link. It can be used to generate the start function that generates an addressed data packet and the through this data packet parametrically controlled target function on the identical information knot run off. The transmission media assignment tables can already be used expediently a logical network, its own information node instead of a physical transmission assign mediums.  

In a variant of the method, simply changing assignment tables becomes a Efficient redirection of logically addressed data packets to a different function than the previous one causes. The logical addressing of the data packet by the generating packet remains Start function to a virtual target function exist. The respective start function remains from the Modification unaffected; the origin of the data to be redirected is therefore immaterial.

Any transmission media, node and / or function assignment tables can be modi be infected.

To modify a mapping table stored locally on an information node a special modification function running on this node is provided, which the Changes the table. This function expediently also carries out corresponding initials configurations and / or reconfigurations (e.g. the corresponding program-controlled transmission facilities when changing the transmission media allocation table).

This modification function is controlled by a parameter data logically addressed to it package that contains new table data, such as B. Set of logical networks, logical Communication partners, logical channels, physical transmission media, physical addresses and / or functions and their assignment to one another.

The target functions affected by a possible modification necessarily have parameter data format identical in groups.

Purposes of such an online-capable and remotely controllable modification can be varied:
The network configuration can also be changed after the allocation table has been initialized; the communication process is flexible and can therefore be influenced in a defined manner. Any functions can be replaced by other functions with different functionality for test and debug tasks.

A system administrator temporarily integrated into the heterogeneous network can access this Wise update the configuration or perform test tasks.

Furthermore, in order to avoid overloading a target information node and / or one Transmission medium or for optimal distribution of the computing load. B. to others Redirect target functions that run redundantly on different information nodes, but have identical information processing behavior.

Advantageously, the node assignment tables only contain a real subset of all physical addresses of the information connected to the respective transmission medium node, which only includes the addresses which the relevant information node actually (and expected) for communication. This limitation prevents you from accidentally incorrect addressing of data packets to the excluded information nodes; the The security of the communication process in the heterogeneous network is increased.

A variation of the invention is that logical channels are prioritized. The use of a common resource, such as B. a transmission medium or a destination information mation node, is usually by setting priorities and - if the same priori activities - regulated according to the FIFO principle. Can be controlled z. B. the order and / or the nesting ratio of the use of a common resource.

The prioritized use of the shared resource concerns the sending of generated data packages, which according to their logical addressing in connection with the respective over transmission media assignment table are to be sent via an identical transmission medium, the transfer of data packets to target functions, which are on exactly one information node expire, as well as the execution of the same target functions, which by the transferred data packets can be controlled parametrically.

The prioritization of the generated data packets in relation to shared resource use takes place according to the priority assigned to the relevant logical channel with which the Data packet was addressed logically. The logical channels are individual and / or prioritized in groups.  

Ideally, data packets that are not sent immediately or that functions are transferred can be temporarily stored in a buffer.

An advantageous further development of the invention serves to increase the reliability of the Communication in a heterogeneous network.

For this purpose, information nodes have a receive buffer with a defined limited size. This is determined in such a way that all of them are temporarily in the receive buffer within a defined period of time stored data packets can be processed by assigned functions.

A completely filled receive buffer reflects the overload of the target information knot, d. H. the information node is not ready to receive.

Furthermore, there is no indirect readiness to receive if this target information fails node and in the event of failure of the relevant physical transmission medium.

The readiness to receive is defined analogously in the event that start and destination information nodes are identical; only the ready-to-receive buffer of the information node is measured here giving.

According to subclaim 4, a data packet to be sent is dependent on the reception Readiness of the respective target information node either either sent to it or as Parameters of a special channel-dependent function, the error handling function (Error handler), passed. With the transfer to the error handling function or with the sending the data packet in question is removed from the send buffer.

The error handler, which according to program modules on the start information node runs, performs defined tasks after the data packet has been transferred to it.

Ideally, one of these tasks is to logically new the transferred parameter data packet to address, the content of which remains unchanged. In the event of failure or overloading one Information nodes or a physical transmission medium grant redundant Functions on another information node thus replacement, or it becomes a redundant physical transmission medium used for transport.

Another task can be the generation of data packets, for example for warning purposes are logically addressed to defined diagnostic and debug functions; who won NEN information z. B. serve to optimize the structure of the network.

The error handlers can also expediently assign the assignment tables to the modification radio Modify parameterized data packets (e.g. permanent rerouting); this enables, for example, self-repairing heterogeneous networks.

A preferred variation of the invention is to ensure real time capability through Introduction of timeout mechanisms in connection with error handling functions, their Another particular effect is the increase in the reliability of communication in hetero network.

For this purpose, each data packet generated by a function with a Lifetime (death line) specifies the temporal validity of the data packet in question characterized and relates to the local time in the start information node. The timestamp For example, "Death Line" can consist of the components "Generation time" and "Life duration ".

Each data packet to be sent, which is in the send buffer of the respective start information node is temporarily stored, at least immediately before it is removed from it Buffer for transmission purposes (and optionally at any other previous times) to Over Exceeded the lifetime assigned to him examined.

If this death line is exceeded, the data packet is transferred from the transmission media spec fish send device to said channel-dependent error handling function as parameters to hand over.  

With the transfer to the error handling function, the data packet in question is removed from the Send buffer removed, i. H. it is not sent to the assigned destination information node. The cause of the lifetime being exceeded can be the overload of the respective transmission be medium.

Furthermore, in the event that a signal that cannot be sent due to a lack of readiness to receive Data packet was left in the send buffer without immediate error handling, its lingering in Buffers can also cause their lifespan to be exceeded.

Similarly, the receive buffers - as stated - are designed in such a size that they are emptied can take place within a time period relevant for real-time applications.

Ideally, data packets with a longer lifespan - in particular with measured values as Content - not logically addressed again by the corresponding error handling function. This procedure has the advantage that in the event of an overload not exclusively outdated data packets are transferred, but only a selection of those that are still valid at the time Data packets are sent and processed.

An advantageous extension of the invention is given by claim 6.

Here the program control of an information node is changed by a data packet, which contains the new program code to one on the relevant information node special function is logically addressed and passed to it as a parameter.

This download function can e.g. B. (invariant) part of a bootable and networkable operating system be the original configuration of that information node.

After transfer to the download function, it saves the information node-specific Program code on the target information node is non-volatile as a new program, resolves choice show a boot process or switch to the new program.

All necessary initializations of the information node are carried out, which ones also optionally a new implementation of the information node-specific assignment tables included.

The new program control is decisive for the process of all new parametrically controllable Information node functions.

This variant of the invention is particularly advantageous in terms of the good maintainability of the Program codes from such information nodes that are difficult to reach physically / physically are.

The following embodiment is intended to illustrate the invention in connection with the figures explain.

The drawings show:

Fig. 1 A heterogeneous network of different networks, and information nodes;

Fig. 2 data flow scheme in an exemplary information node.

In Fig. 1, a heterogeneous network is exemplified, which separate from the differently shaped physical transmission media LAN (1), and two CAN buses (2, 3).

The heterogeneous network also includes the information nodes (program-controlled information processing machines) PC ( 4 , 5 ), workstation ( 6 ), sensor ( 8 ) and actuators ( 7 , 10 , 11 , 12 ), which have access to these transmission media and thus participate in the information exchange.

Here only the PC ( 4 ) has direct connections to all three transmission media at the same time; it can thus act as a bridge between these media.

In each information node, a platform-specific implemented program code is stored in the program memory, the application-specific program modules of which are decisive, among other things, for boot and initialization processes, for general operating system tasks including administration of the network connection, for the control of the transmission and transmission units specific to the transmission medium as well as for the execution of parametrically controllable functions. In the example, the program code of the sensor ( 8 ) also contains modules of a download function which non-volatilely stores a new program code sent to it via the network in the program memory of the sensor and triggers a booting process. The associated code of the boot routine is designed in such a way that a change is made to the new program code after a boot process.

In the example, the range of functions of the parametrically controllable functions (F1,..., Fm) includes u. a. the Control of hardware, control of other functions, processing of over given parameters, the forwarding of the parameters to other functions, the measured value extraction and forwarding, the parametric modification of assignment tables and the Error handling.

These functions are designed in such a way that data packets with a precisely defined function specific data format can be passed as parameters that control this function. Furthermore, at least a subset of the entire functions of the heterogeneous network is like this designed that - depending on the application - data packets (e.g. with control information and / or measurement values as content) and can be addressed to a virtual function.

To meet the start condition, a module is provided in the startup program code of the workstation ( 6 ), which initiates the generation and logical addressing of a data packet to a first virtual function and thus initiates a continuous communication process. The expiry of the functions is ideally understood to mean a function call with the parameter data packet transfer, but parallel, permanent function sequences with polling for parameter data packets ready for transfer are also possible; the functional sequences can also be partially implemented using efficient hardware.

In the example, the program modules of the bridge functions of the PC ( 4 ) are also a formal part of the operating system and are designed as effectively working short circuits within the management of the network connection.

In the example, error handling functions (FF1,..., FFn) are provided in accordance with the fourth subclaim. in the example in the same number as the total number of through the functions of this information node-addressable logical channels that have a channel-specific parameter data format point. Data packets which are based on the same information are transferred to these error handlers nodes were generated (or re-addressed), but not or not in time to the target information mation nodes can be transferred. These error handlers can also logically address Generate data packets.

The send buffer (SP) shown in FIG. 2 works according to the FIFO principle and, in the example, is arranged arbitrarily in the data flow scheme in such a way that it receives functionally generated and logically addressed data packets and, depending on the send capacity, transfers them to the network management device. which resolves its logical address step by step based on the assignment tables and transfers the data packets to the corresponding sending devices.

The receive buffers (EP) of the information nodes are in the data flow scheme between receive facilities and function assignment tables are arranged and are also after FIFO principle organized.

In this arrangement, the transmit buffer and receive buffer of the PC ( 4 ) are divided into logical channel groups with different priorities; the receive buffers of the sensor ( 8 ) are not subdivided and are searched for packet extraction for data packets with the highest priorities.

Furthermore, each information node has several locally valid, unique assignment tables (ÜZT, KZT1,..., KZT3, FZT), which are stored locally non-volatile locally, in the example in the form of an "INI file stored on the hard disk of the PC ( 4 ) "and as a binary table in an EEPROM in the sensor ( 8 ).

The assignment tables of each information node contain a defined basic assignment after initial initialization. On the one hand, this basic assignment can be varied manually using special tools of the relevant information node (e.g. PC 4 ) or a temporarily directly connected additional administrator tool, and the specific network configuration can be adapted.

The basic assignment can also be designed in such a way that communication of all information nodes of the heterogeneous network is made possible, which permits a remote variation of the assignments via the aforementioned modification functions. In other words, during an initialization process, an administrator can use a tool to remove the assignment tables from any suitable information node (e.g. stationary host computer ( 6 ) or laptop ( 9 ) temporarily inserted into the network) depending on the available transmission media, Modify information nodes and functions that can be executed on them as required. The settings made are retained due to their non-volatile storage after the respective information node has been rebooted.

In the example, the transmission media assignment tables contain the unique one Assignment of logical networks to physical transmission media e.g. B. Data about that relevant medium, such as type and connection type.

In the example, the node assignment table of the sensor ( 8 ) contains only the physical address of the information node PC ( 4 ); by this subamount inadvertent addressing of the actuator (7) is avoided by the sensor (8) according to any faulty node mapping tables modification.

Specifically, the node assignment tables KZT1, KZT2 of the information node (IK0) in FIG. 2 contain clear assignments of logical communication partners to the information nodes IK11, IK12, IK0 and to IK21, IK22, IK0; the node assignment table KZT3 contains assignments only to IK0. The own information node (IK0) is therefore included in these tables.

Furthermore, the transmission media assignment table (ÜZT) contains unique assignments of logical network names for the transmission media ÜM1, ÜM2 and for a network simulation module.

The function allocation table (FZT) contains an example of: a. the assignment of the logical Channels K2 and Kn for function Fm and channel K1 for function F3.

Data flow variables shown schematically in FIG. 2 stand for a transport of data packets within the relevant information node or from / to a further information node. The data flow D1 represents the transport of data packets generated and logically addressed by the functions (F1,..., Fm) or by the error handling functions (FF1,..., FFm) into the send buffer (SP).

Furthermore, the data flows (D2,..., D5) represent the transmission from the transmission buffer (SP) ent received data packets (D10) via the corresponding physical transmission media ÜM1 or UM2 to the information node IK11,. . ., IK22.

The data flows D6 and D7 show the receipt of data packets and their classification in the Receive buffer (EP).

The data transport (D6) of data packets whose destination information nodes correspond to the Node assignment tables (KZT1,..., KZT3) to IK0 is resolved to the receive buffer (EP) takes place directly without the involvement of the transmission media-specific transmission facilities. The data flow D8 symbolically shows the withdrawal of the corresponding logical channels (K1,..., Kn) specified data packets for assignment to functions (F1,..., Fm) by means of functions allocation table (FZT) and the subsequent transfer to it.

Finally, the channel-dependent data flow D9 is from the send buffer (SP) to error handling functions (FF1,..., FFn) of those data packets that are not or not within could be sent halfway through their valid lifetime.

Claims (6)

1.Procedures for platform-independent communication via a heterogeneous network, consisting of any physical transmission media, between several spatially separated program-controlled information processing machines and / or sensor and / or actuator units as information nodes for the purpose of remote information processing and / or control by parameter-controlled functions, which run in accordance with the platform-dependent program modules existing on the respective information node,

• - with a distributed operating system;
• - With transmission media assignment tables, which contain a unique assignment of logical network names to physical transmission media connected to the information node;
• - With transmission media-specific node assignment tables, each of which contains a unique assignment of logical communication partners to information nodes connected to a physical transmission medium;
• - With function assignment tables, which each contain a unique assignment of logical channels to functions running on the information nodes;
• - With program-controlled transmission media and platform-specific devices for the respective sending of any formatted data packets from the start information node via a physical transmission medium to a destination information node connected to this medium, which by logical network names and logical communication partners in connection with the transmission media and nodes -Assignment tables is determined
• - and with facilities for the respective reception of these data packets;
  characterized in that
  • a) at least one of these functions in each case generates at least one data packet specified by a logical address consisting of a logical network name, logical communication partner and logical channel;
  • b) each of these data packets is sent from the respective start information node to a respective destination information node;
  • c) these data packets received from the respective destination information node are each passed as parameters to a function running on this information node, which is determined by the logical channel in connection with the function assignment table specific for this information node, whereby
  • d) the transmission media, node and function assignment tables are specific to the information node and are valid for precisely the information node on which they are locally non-volatile stored locally;
  • e) the data packet has a channel-dependent data format which is independent of the physical transmission medium and of the destination information node;
  • f) functions to which logically addressed data packets can be assigned as parameters can generate any further logically addressed data packets in accordance with their program module;
  • g) the respective start and destination information nodes can be identical.

2. The method according to claim 1, in particular for the purpose of changing the network configuration,
with a plurality of functions running on information nodes which have identical parameter data format in groups,
characterized in that
the information node-specific transmission media, node and / or function assignment tables are modified by means of at least one function running on the respective information node as a function of a data packet which is assigned to this function in accordance with its logical addressing as parameters, preferably
when modifying a transmission media assignment table, the corresponding transmission media-specific transmission devices are configured, and / or
each node assignment table receives a subset of all the physical addresses of the information nodes connected to the respective physical transmission medium required for the communication of the respective information node. 3. The method according to claims 1 and 2, in particular for the purpose of prioritized remote information processing and / or control,
with send and receive buffers located on the information nodes,
characterized in that

• a) the generated logically addressed data packets are specified with a priority dependent on the logical channel, whereby these channels can be given equal priority in groups;
• b) these data packets are transferred to a send buffer located on the respective start information node and temporarily stored there;
• c) are each sent via identical physical transmission media and / or data packets to be sent to an identical destination information node in a multiplexed manner, the sending taking place in its sequence and / or in its interleaving ratio in accordance with the priorities assigned to the respective logical channels;
• d) these data packets on the destination information node are transferred to a receive buffer and temporarily stored there;
• f) the sequence of the transfer of these data packets stored in the reception buffer to the assigned target functions and the sequence and / or the nesting ratio of the sequence of these functions is determined by the priorities assigned to the respective logical channels.

4. The method according to claims 1 to 3, especially for the purpose of increasing reliability, with receive buffers and with parameter-controlled error handling functions, characterized in that a data packet to be sent in each case from the transmission media-specific one Sending device of the start information node depending on the readiness of the Target information node is either sent to the target information node or as Parameters of a function assigned to the logical channel, which is program-controlled on the Start information node expires, is passed for error handling, each receive buffer is limited in size.   5. The method according to claims 1 to 4, in particular to ensure real-time capability, with parameter-controlled error handling functions, characterized in that

• a) each generated data packet is specified by the generating function with a lifetime,
• b) each data packet temporarily stored in the send buffer of the start information node is removed from the send buffer depending on the expiry of its lifetime and is passed as a parameter to a function assigned to the logical channel, which runs on the start information node under program control, for error handling.

6. The method according to claims 1 to 5, in particular for the purpose of modifying the program code of the information node, characterized in that

• a) a data package that is logically addressed to it is transferred as a parameter to a function running on an information node, the relevant program module of which can be part of a bootable and networkable operating system,
• b) this function stores the parameters passed to it as a new program code in the relevant information node in a non-volatile manner and triggers a program-controlled reinitialization of this information node.