DE102017012250A1 - Transferring data on a local bus - Google Patents

Abstract

A method for operating a local bus (6), in particular a ring bus, with data bus users (7a, 7b, ..., 7n) is described. Furthermore, a local bus master (3) and the data bus users (7a, 7b,..., 7n) are described. The method comprises transmitting a first identifier (18) of a cycle frame (17) via the local bus (6), the first identifier (18) defining the beginning of the cycle frame (17), transmitting process data (28) via the local bus (6 ) in at least one isochronous data packet (25), wherein the at least one isochronous data packet (25) has a second identifier (26), the second identifier (26) being different from the first identifier (18), transmitting management data (34, 39b , 40b) via the local bus (6) in at least one asynchronous data packet (30, 35), wherein the at least one asynchronous data packet (30, 35) has a third identifier (31, 36), wherein the third identifier (31, 36) different from the first identifier (18) and second identifier (26) and wherein the isochronous data packet (25) and the asynchronous data packet ( ₃₀ , ₃₅ ) are transmitted within the cycle frame (17).

Description

Field of the invention

The invention generally relates to transmitting data on a local bus.

State of the art

Process data and management data are mostly used in the context of automation equipment but are not limited thereto.

Automation systems are used in particular for the control of industrial plants, buildings and means of transport. For the control of an automation system usually several sensors and actuators are necessary. These monitor and control the process performed by the plant. The different sensors and actuators of an automation system are often referred to as automation devices.

These automation devices can either be connected directly to a control system of the automation system, or can first be connected to input and output modules, which are often referred to as I / O modules. These can in turn be connected directly to the controller. The automation devices can either be integrated directly in the I / O modules or can be connected to them via cable or wirelessly.

The control of an automation system is usually accomplished with the help of one or more programmable logic controllers, PLC. The PLCs can be arranged hierarchically or decentrally in an automation system. There are different performance classes for the PLC, so that they can take over different controls and regulations depending on the computing and storage capacity. In the simplest case, a PLC has inputs, outputs, an operating system (firmware) and an interface via which a user program can be loaded. The user program defines how the outputs are to be switched depending on the inputs. The inputs and outputs can be connected to the programmable controllers and / or the I / O modules, and the logic stored in the user program can be used to monitor or control the process performed by the automation system. In this case, the monitoring of the process is accomplished by the sensors and the control of the process by the actuators. The controller can also be referred to as a central controller or central unit and assumes control of at least one automation device or I / O module connected to the controller.

However, the direct connection of the automation devices to the at least one controller or the I / O modules to the at least one controller in the form of a parallel wiring, i. Each automation device or each I / O module relocates one line to the higher-level control, which is very expensive. Especially with increasing degree of automation of an automation system, the cabling effort increases with parallel wiring. This is associated with great effort in the design, installation, commissioning and maintenance.

For this reason, automation systems usually use bus systems today, with which the automation devices or the I / O modules can be connected to the controller. Such subscribers of a bus system are also referred to as bus subscribers. Because data is exchanged on the bus system, bus subscribers are also often referred to as data bus subscribers. In order to simplify the connection of the individual automation devices or the I / O modules with the bus system even more, nowadays individual groups of automation devices or I / O modules with the help of a specialized local bus are initially connected to each other to a local bus system and then at least one Subscriber of this local bus connected to the bus system, which is connected to the controller. In this case, the local bus system may differ from the bus system, which is used to realize the connection with the controller.

The subscriber of a group of local bus subscribers connected to the bus system of the controller is often referred to as a local bus master. Alternatively, the term headend of the local bus system is used. In comparison to other local bus subscribers, this local bus master can contain further logic, circuits or functionalities which are necessary for connection to the bus system of the controller. Also, the local bus master itself may include a PLC. This subscriber can also have logic and circuits for conversion between the two bus systems. The local bus master can therefore also be designed as a gateway or bus converter and ensures conversion of the data present in the format of the one bus system into the format of the local bus system and vice versa. In most cases, however, not mandatory, the local bus master is specialized in the connection of the local bus to the parent bus.

The local buses used are mostly tailored to the specific application requirements of the automation devices or I / O modules or take into account their special hardware design. The groups of automation devices or I / O modules of the local bus system usually form a subgroup of the automation system for performing a specific task in the process performed by the automation system. The data exchanged on the buses for the process are also often referred to as local bus data or process data, because these data include information for controlling or controlling the executed by the automation system process. These data may include, among other things, measurement data, control data, status data and / or other information that cause regulations or controls on the data bus users within a precisely defined time period or a precisely defined time. Depending on the bus protocol used, this data may be preceded by other data (English: headers) or attached (English: Trailer). These other data may include information regarding the data or include information regarding internal communication on the local bus. Here, a variety of different information is known, which can be preceded or added to the data according to the bus protocol used. Furthermore, there is data that cause control, regulation or programming of the data bus participants outside of a defined period of time or outside a precisely defined time. Process data can often be referred to as cyclic data in the context of automation systems, because the process is controlled in the automation system relies on cyclic process data that allow the data bus participants controls and / or regulations of the example connected to the data bus participants actuators and sensors to accomplish. In contrast, management data is used to program the data bus users or, for example, to query their error messages, status, etc.

A ring bus is a specialized form of local bus, such as US 5,472,347 A known. In a ring bus, the data bus users, for example the automation devices or I / O modules, are each connected to their directly adjacent data bus users and data is forwarded in succession from one to the other data bus user. The data transmitted on the local bus can also be referred to as local bus data. Thus, not all data bus subscribers are sent the data at the same time, but in turn, with a data bus subscriber receiving data from his upstream data bus subscriber and forwarding data to his downstream data bus subscriber. Between receiving the data and forwarding, the data bus user can process the received data. When the data has reached the last data bus subscriber in the series, the data from the last data bus subscriber is returned back to the first data bus subscriber in turn. The return can be done either by all data bus participants or past them with the help of a bypass line. So the ring bus has a down stream and up stream of data. The data in a ring bus are usually transmitted in the form of data packets that pass through all data bus users.

In a ring bus, the data packet is forwarded from one to the other data bus subscriber. At any given time, a data bus subscriber always receives only a portion of the data packet from its upstream data bus subscriber. When the data contained in this part has been processed by the data bus subscriber, the part is forwarded to the downstream data bus subscriber and at the same time a new part of the data packet is received by the upstream data bus subscriber. In this way, all parts of the data packet pass sequentially all data bus users.

The object of the present invention is to provide a method and a local bus master for improved time management in ring bus systems.

Summary of the invention

This object is achieved with a method and a local bus master according to the independent claims. Advantageous embodiments are described in the subclaims.

An inventive method for operating a local bus with data bus participants is described, wherein the local bus is in particular a ring bus. The method comprises the step of transmitting a first identifier of a cycle frame, wherein the first identifier defines the start of the cycle frame. A cycle frame can be, for example, a recurring (cyclic) preferably equidistant time interval within which data can be transmitted on the local bus. In this case, the cycle frame has, for example, at least one first identifier, which can also be referred to as the start identifier SOC (Start Of Cycle), and which defines a time range for transmitting the data with a following first identifier. Several first identifiers consecutive cycle frames are advantageously at a time equidistant from each other. The first identifier can contain a unique bit pattern SOC. If this bit pattern is detected by the data bus users, they know that a cycle frame has started, ie at certain time intervals to the SOC process data will follow and follow SOC management data at fixed intervals. In the context of the invention, time can refer to the absolute time or to corresponding work cycles.

The inventive method further comprises the step of transmitting the process data and management data via the local bus, wherein the process data and management data are transmitted within the cycle frame. The process data is used at the data bus users to provide control and / or regulation of a process. For example, they control the setpoints for actuators connected to the data bus users or regulate limit values for recorded sensor values. The management data has data that is used to manage the data bus subscribers, ie, for example, to include the programming of the data bus subscribers or, for example, to interrogate states. However, management data can also be used to initialize the local bus, for example, to assign addresses to the data bus subscribers or to query their addresses. Management data preferably contains no process data.

In the method according to the invention, at least one isochronous data packet containing the process data is transmitted at a first time interval to the first identifier, and if management data is to be transmitted within the cycle frame, then this management data is transmitted disjointly to the process data. That the management data is not transmitted in the at least one isochronous data packet together with the process data, but within the same cycle frame. At the same time, management data and process data are not mixed.

In other words, first the first identifier is sent from the local bus master to the local bus. The first data bus subscriber receives the first identifier and is aware that a cycle frame is starting. The first data bus subscriber then transmits after a preferably defined predetermined or fixed time - e.g. Thus, the first predetermined time is, for example, the particular or fixed delay by a data bus subscriber for relaying each symbol to the following data bus subscriber. That it can be said that the first identifier is transmitted on the local bus because this first identifier passes through all the data bus users of the local bus. At a first time interval from the first identifier, the local bus master sends the first symbol of the at least one isochronous data packet. This symbol is also received by the first data bus subscriber and forwarded to the respectively following data bus subscriber after a defined, predetermined or fixed time, etc. The same happens with the further symbols of the at least one isochronous data packet. That it can be said that the at least one isochronous data packet is transmitted on the local bus because all parts of the at least one isochronous data packet pass through all the data bus users.

If the defined predetermined time is constant at all data bus subscribers, the time interval between the first identifier and the first symbol of the at least one isochronous data packet also remains the same. It can also be said that the first identifier and the parts of the at least one isochronous data packet pass through the local bus, that is to say the data bus users, at a constant speed. Disjunkt to the at least one isochronous data packet sends the local bus master management data, so these can either be sent in time before the at least one isochronous data packet or after the at least one isochronous data packet, if the isochronous data packet is not adjacent to the first identifier or to a subsequent first identifier , The management data is also received by the data bus subscribers and forwarded to the respective subsequent data bus subscriber after a defined predetermined time, and so on. it can be said that the management data is transmitted on the local bus.

Due to the fact that process data and management data are transmitted together within a cycle frame, there is the advantage that the communication with the data bus users does not have to be interrupted when switching between isochronous process data and management data. Furthermore, it is also possible to change the programming of the data bus subscribers for, for example, each isochronous data packet, namely by prefacing the isochronous data packet with management data. By transferring isochronous process data and management data within a cycle frame without interrupting communication, the best possible time management can be ensured.

In a preferred embodiment of the method according to the invention, this is at least an isochronous data packet has a second identifier that is different from the first identifier. This identifier of the isochronous data packet may be a one-to-one bit pattern IDE. The data bus users know that if this bit pattern occurs, isochronous data will follow process data. The local bus master may be adapted to send this second identifier at the first time interval from the first identifier to the local bus followed by the process data. The second identifier and the process data are each received by the data bus subscribers and forwarded at a defined predetermined or fixed time to the respective subsequent data bus subscriber etc., so that in this way the isochronous data packet is transmitted on the local bus.

In a preferred embodiment of the method according to the invention, instead of an isochronous transmission of the management data, the management data is transmitted in at least one asynchronous data packet. An asynchronous data packet is transmitted only when necessary, that is, when pending transfer of management data. If no management data is available for transmission, no asynchronous data packets are transmitted within a cycle frame. A data packet is transmitted asynchronously if it is not necessarily always at the same time interval from the cycle frame to subsequent cycle frames in the same time interval to the first identifier. In contrast, isochronous data packets must always be transmitted within each cycle frame at the same interval from the first identifier. Both isochronous data packets and asynchronous data packets are preferably aligned with a clock signal of the local bus.

The asynchronous data packet may have a third identifier which is to be shifted to the first identifier, ie the identifier which indicates the start of a cycle frame and the second identifier, ie the identifier which indicates an isochronous data packet. The third identifier can also be an associated bit pattern, which is known to the data bus users, so that they know on receipt of the third identifier that an asynchronous data packet is present and accordingly the third identifier asynchronous data thus follow management data. The local bus master may be adapted to send this third identifier to the local bus. The third identifier and the management data are respectively received by the data bus subscribers and forwarded at a defined predetermined or fixed time to the respective subsequent data bus subscriber etc., so that in this way the asynchronous data packet is transmitted on the local bus.

In a preferred embodiment of the method according to the invention, this further comprises the step of determining the first time interval. That It is determined how much time is between the transmission of the first identifier and the transmission of the first symbol of the at least one isochronous data packet. The first time interval is preferably determined based on the number of data bus subscribers and a predetermined or calculated delay in the transmission of the process data.

The determination can be accomplished, for example, by the local bus master. The first time interval preferably indicates what time is between the transmission of the first identifier and the transmission of the second identifier. If all data bus users are adapted to have the respective received symbol only for a constant time and then forward it to the subsequent data bus subscriber, this time interval remains the same between the transmission or forwarding of the first identifier and the transmission or forwarding of the second identifier ,

How much time must elapse between the transmission of the first identifier and the transmission of the first symbol of the at least one isochronous data packet is directed in an advantageous embodiment according to when the process data contained in the isochronous data packet must be present at the data bus participants, a control and / or regulation perform. In particular, the lowest possible latency may be required. For example, the local bus master may have knowledge as to when the process data must be present at the respective data bus subscribers, so that all data bus subscribers may perform controls and / or controls simultaneously or at least within a limited amount of time. From this knowledge and the knowledge of how much time it takes to transmit the isochronous data packet, which depends on the number of data bus subscribers, the local bus master can determine when the at least one isochronous data packet has to be transmitted or when the first symbol of the at least one Isochronous data packets must be sent so that all data bus users have their respective process data in time. The person skilled in the art is aware that the presence of the process data at the respective data bus users is also dependent on the distribution of the process data within the at least one isochronous data packet.

The local bus master can be adapted to store the determined time interval. Furthermore, the local bus master may be adapted to use the same time interval until the configuration of the local bus again, ie, until data bus users are added or removed. The local bus master can be adapted in such a way that it determines the time interval when the local bus is initialized for the first time. Also, the local bus master may be adapted after initialization to check the time interval at fixed time intervals or triggered by a configuration change of the local bus. The first time interval can alternatively be calculated by an external program, for example on a desktop PC or on the PLC connected via a fieldbus.

The point in time at which the process data must be available to the data bus users can also be referred to as the output time, because at this time the process data is output at the outputs of the data bus users. By outputting the process data at the outputs of the data bus users, for example, actuators can be controlled or regulated. This output time can be fixed and have a second time interval from the first identifier. In this case, the second time interval defines the time that elapses between the transmission of the first identifier by the local bus master and the output time. The second time interval is different for each data bus subscriber. The second time interval is determined for each data bus subscriber in dependence on the position of the data bus subscriber in the local bus. Preferably, each data bus subscriber is informed of his individual second time interval by means of the management data.

In a further embodiment, the specification of the output time point takes place with the aid of an absolute time specification. The data bus users all work in this case with a common time base. For example, all are synchronized to a timer. According to an advantageous embodiment, the first identifier contains a time stamp, which is evaluated by the data bus users, for example, to correct their own time base.

In accordance with a fixed output time, there may also be a fixed input time which specifies an input of process data to the inputs of the data bus users. This input time may be, for example, the time at which the data bus users receive values from the sensors connected to the data bus users. The input time may be a third time interval away from sending the first identifier. The recorded values can also represent process data and can be queried by the data bus users within the cycle frame with the aid of a further isochronous data packet, so that the local bus master can forward the corresponding process data to a higher-level controller. The local bus master can be adapted, for example, to transmit a further isochronous data packet on the local bus with a fourth time interval to the first identifier, the fourth time interval being determined based on the input time at the data bus users, so that the further isochronous Data packet, or parts of the isochronous data packet present to the data bus participants at a time when they have already read the values from their inputs and are ready to write this in the other isochronous data packet or the part of the further isochronous data packet available to them.

The above-mentioned object is also achieved by a local bus master according to the invention of a local bus, in particular a ring bus, with data bus users. The local bus master has a means for transmitting a first identifier of a cycle frame, wherein the first identifier defines the beginning of the cycle frame. The means for sending is adapted to send process data and management data over the local bus, the process data and management data being transferable within the cycle frame. In the case of the local bus master according to the invention, the means for transmitting is adapted to send at least one isochronous data packet containing the process data at a first time interval from the first identifier. If management data is transmitted within the cycle frame, the means for sending is adapted to send this management data disjoint to the process data. The means for transmitting may be, for example, a circuit, in particular a transceiver circuit. The circuit may be implemented in an application specific integrated circuit (ASIC) or field programmable (logic) gate array (FPGA). The means for transmitting may also comprise an encoder which encodes the data to be transmitted on the local bus. The means for transmitting may also comprise a modulator which modulates the data to be transmitted on the local bus.

In a preferred embodiment of the local bus master according to the invention, the means for sending is further adapted to send the management data in an asynchronous data packet.

In a preferred embodiment of the local bus master according to the invention, the latter also has a means for determining the first time interval based on an output time, which specifies outputting of process data at an output of the respective data bus users, wherein the output time is predetermined at a second time interval to the first identifier ,

In a preferred embodiment of the local bus master according to the invention, the means for determining is adapted to determine a fourth time interval to the first identifier based on an input time which specifies an input of process data at an input of the respective data bus users. In this case, the input time is predetermined or determined at a third time interval to the first identifier. The means for transmitting is adapted to send at least one further isochronous data packet in the cycle frame at a fourth time interval to the first identifier. In this case, the further isochronous data packet can be used to query the values at the inputs of the respective data bus users. In this case, the local bus master can furthermore have a means for receiving process data.

list of figures

• 1 ein schematisches Blockdiagramm einer beispielhaften Automatisierungsanlage mit einer speicherprogrammierbaren Steuerung und einem beispielhaften Ringbus;
• 2 eine schematische Darstellung eines Zyklusrahmens;
• 3 eine schematische Darstellung eines isochronen Datenpakets bestehend aus Symbolen, wobei einige Symbole Prozessdaten tragen;
• 4 eine schematische Darstellung eines asynchronen Datenpakets bestehend aus Symbolen, wobei einige Symbole Managementdaten tragen;
• 5 eine schematische Darstellung eines weiteren asynchronen Datenpakets bestehend aus Symbolen, wobei einige Symbole Managementdaten tragen; und
• 6 eine beispielhafte zeitliche Abfolge von asynchronen und isochronen Datenpaketen innerhalb eines Zyklusrahmens.

The invention will be explained in more detail with reference to embodiments with the accompanying drawings. From the described embodiments, further details, features and advantages of the subject invention. Show it:

• 1 a schematic block diagram of an exemplary automation system with a programmable logic controller and an exemplary ring bus;
• 2 a schematic representation of a cycle frame;
• 3 a schematic representation of an isochronous data packet consisting of symbols, some symbols carry process data;
• 4 a schematic representation of an asynchronous data packet consisting of symbols, some symbols carry management data;
• 5 a schematic representation of another asynchronous data packet consisting of symbols, some symbols carry management data; and
• 6 an exemplary time sequence of asynchronous and isochronous data packets within a cycle frame.

Description of preferred embodiments

1 shows a schematic block diagram of an automation system. It will be understood by those skilled in the art that the automation system shown is only an example and all the elements, modules, components, participants and units belonging to the automation system can be configured differently but can nevertheless fulfill the basic functions described here.

In the 1 shown automation system has a higher-level control 1 on, which can be realized for example with a programmable logic controller, PLC. Such a PLC 1 basically serves to control and regulate the process performed by the automation system. Nowadays PLCs take over 1 In automation systems, however, also more extensive functions, such as the visualization, alarm and recording of all process related data and as such, the PLC acts 1 as a human-machine interface. There are PLCs 1 in different performance classes, which have different resources (computing capacity, memory capacity, number and type of inputs and outputs, and interfaces) that the PLC 1 allow to control and regulate the automation system process. A PLC 1 Mostly has a modular design and consists of individual components, each fulfilling a different task. Usually there is a PLC 1 a central processing unit (with one or more main processors and memory modules) and several modules with inputs and outputs. Such modular PLC 1 can be easily expanded by adding assemblies. It depends on the complexity of the process and the complexity of the structure of the automation system, which modules in the PLC 1 must be integrated. In today's automation systems, the PLC 1 also usually no independent system, but the PLC 1 is connected via appropriate interfaces - not shown here - to the Internet or intranet. This means the PLC 1 is part of a network over which or from which the PLC 1 Information, instructions, programming, etc. can receive. For example, the SPS 1 Receive information about the process supplied materials via a connection to a computer located on the intranet or Internet, so that, for example, by knowing the number or nature of the process can be optimally controlled. It is also conceivable that the SPS 1 is controlled by an access from the intranet or Internet by a user. Thus, for example, a user with the help of a computer, also called host computer, on the PLC 1 access and check their user programming, change or correct. Accordingly, the access to the PLC 1 from one or more remote control or control centers. If necessary, the master computers can have visualization devices for displaying process sequences.

The PLC is used to control the process of the automation system 1 With Automation devices connected. In order to keep the wiring costs low, bus systems are used for these connections. In the in 1 embodiment shown is the PLC 1 by means of a higher-level bus 2 which may be a field bus in the embodiment shown here, with a local bus master 3 a subordinate local bus system connected. To the parent bus 2 But not only as in the embodiment shown here, a local bus master 3 A local bus can be connected, but also any other participants - not shown here - to communicate with the PLC 1 are designed.

The parent bus 2 is in the embodiment shown here with the local bus master 3 connected. For this purpose, the local bus master 3 a first interface 4 which is designed so that this with the parent bus 2 can be connected. the interface 4 For this purpose, for example, have a recording in the form of a socket and the parent bus 2 may have a plug which can be received by the socket. In this case, the plug and the socket may be, for example, a modular plug and a modular jack, ie, each wire of the parent bus 2 is electrically or optically connected to a connection in the modular jack. The person skilled in the art, however, also knows other possibilities, such as an interface 4 is to be interpreted, so that the local bus master 3 electrically or optically with the higher-level bus 2 can be connected. The person skilled in the art screw, turn, click or plug connections are known, with the help of which can make an electrical or optical connection. In most cases, a male plug is picked up by a female counterpart. This recording usually does not only produce the electrical or optical connection, but also ensures that the two parts are mechanically coupled and can only be released from each other again with the application of a certain force. But it is also conceivable that the parent bus 2 stuck with the interface 4 wired.

The local bus master 3 in the embodiment shown here has a further second interface 5a . 5b on to the local bus master 3 to connect to the local bus. To the local bus are data bus users 7a . 7b , ..., 7n connected or form this. The local bus is advantageously designed such that one from the local bus master 3 data packet sent by all data bus users connected to the local bus 7a . 7b , ..., 7n and to the local bus master 3 is transferred back. In this case, a data bus subscriber receives 7a . 7b , ..., 7n from its upstream data bus subscriber 7a . 7b , ..., 7n only a part of the data package. After a period of time in which the data contained in this part of the data bus subscriber 7a . 7b , ..., 7n can be processed, the part to the downstream data bus participants 7a . 7b , ..., 7n forwarded and at the same time is from the upstream data bus subscriber 7a . 7b , ..., 7n receive a new part of the data packet. In this way, all parts of the data packet pass sequentially all data bus users 7a . 7b , ..., 7n , The local bus is advantageously formed in an annular structure. Such local buses can also be used as a ring bus 6 be designated. Alternatively, the local bus can also be formed in a strand-shaped or star-shaped manner or from a combination or mixed form of the aforementioned. The sending and receiving of the data packets is via the second interface of the local bus master 3 accomplished. In the embodiment shown here, the second interface is divided into a first part 5a and a second part 5b on. The first part 5a the second interface provides the downlink in the ring bus 6 here and the second part 5b The second interface provides the uplink in the ring bus 6 ago.

The ring bus 6 whose data sending direction is indicated by arrows in the in 1 shown Ausführungsbespiel shown, in the embodiment shown here, the data bus participants 7a . 7b , ..., 7n on. These data bus participants 7a . 7b , ..., 7n each have an interface in the embodiment shown here 8th on to data from an upstream or previous data bus subscriber 7a . 7b , ..., 7n to recieve. In the case of data bus users 7a , this receives via the interface 8th Data from the upstream local bus master 3 , The data on the local bus 6 can also be referred to as local bus data. Furthermore, the data bus users 7a . 7b , ..., 7n in the embodiment shown here in each case an interface 9 on to data to a downstream or downstream data bus subscriber 7a . 7b , ..., 7n forward. In the case of data bus users 7a sends this data to the downstream data bus user 7b over the interface 9 , The interfaces 8th and 9 serve to propagate data in the downward direction of the ring bus 6 ie from the local bus master 3 path. Furthermore, the data bus users 7a . 7b , ..., 7n in this embodiment also interfaces 10 and 11 on, to propagate data in the upward direction of the ring bus 6 ie to the local bus master 3 out. In the case of the data bus subscriber 7a is interface 10 It is designed to receive data from the downstream or downstream data bus subscriber 7b to receive and interface 11 is designed to transfer data to the upstream or previous data bus user, here the local bus master 3 to forward. So it can also be said that the interfaces 9 and 11 Transmitter interfaces are, whereas the interfaces 8th and 10 Are receiver interfaces.

In the embodiment shown here, the connections of the interfaces and the PLC 1 or the data bus users 7a . 7b , ..., 7n implemented by means of cables or printed circuit boards for direct or indirect contacting by means of electrical contacts. Another alternative is that the individual connections are made wirelessly, and the interfaces provide the necessary conversions to the radio standards used.

Even if the local bus master 3 and the individual data bus users 7a . 7b , ..., 7n are shown spaced apart in the embodiment shown here, the local bus master 3 that is decentralized arranged by the data bus participants 7a . 7b , ..., 7n , the person skilled in the art is aware that the data bus users 7a . 7b , ..., 7n and the local bus master 3 - The also a data bus participant of the ring bus 6 represents - can also be connected directly with each other. In this case, for example, contacts of a data bus subscriber can access corresponding receptacles or receptacle contacts of a directly adjacent data bus subscriber so as to establish an electrical connection between the data bus users so that data can be transmitted in the downward and upward direction. For example, the data bus users 7a . 7b , ..., 7n have on the side facing away from the master recordings and on the side facing the master contacts. Become the data bus participants 7a . 7b , ..., 7n then strung together accordingly, so grab the contacts of a data bus participant 7a . 7b , ..., 7n in each case in the recordings of the other data bus subscriber 7a . 7b , ..., 7n and an electrical connection can be created. The local bus master 3 then has corresponding recordings on the page which are in the contacts of the first data bus subscriber 7a grabbing so between the interfaces 5a and 8th or the interfaces 5b and 11 to create an electrical connection. However, the person skilled in the art also knows of other possibilities, for example pressure contacts, blade and fork contacts, such as two data bus users arranged directly next to one another 7a . 7b , ..., 7n can make an electrical or optical connection.

In the case of the data bus users 7a . 7b , ..., 7n and the local bus master 3 be directly connected to each other, they may also have mechanical recordings or mechanical fasteners with which the individual Datenbusteilnehmer 7a . 7b , ..., 7n and the local bus master 3 can be connected to each other. In this case, for example, a data bus subscriber 7a . 7b , ..., 7n have a projection on one side and an undercut on the other side. Become the data bus participants 7a . 7b , ..., 7n then strung together, so engages a projection in an undercut of the other data bus subscriber 7a . 7b , ..., 7n so that a mechanical coupling is created. For simple juxtaposition of data bus users 7a . 7b , ..., 7n These can also be arranged on a common recording, for example, a DIN rail. The data bus users can be attached to the DIN rail 7a . 7b , ..., 7n have corresponding fastening means. Alternatively or additionally, the data bus users 7a . 7b , ..., 7n Also, for example, releasably connectable fastening means, with which the data bus participants 7a . 7b , ..., 7n can be attached either to the DIN rail or to another recording. For this purpose, the releasably connectable fastening means can be exchangeable and a corresponding fastening means for the desired recording can with the Datenbusteilnehmern 7a . 7b , ..., 7n be connected so that they can be attached to the desired recording.

Furthermore, the data bus users 7a . 7b , ..., 7n in the 1 embodiment shown, a processing unit 12 on, which consists for example of a processing component and a logic unit, which in 3 are shown in more detail. The processing unit 12 may also be referred to as the overall circuit of the data bus subscriber. That is, the processing unit 12 receives data through inputs 8 and 10 and outputs data to the outputs 9 and 11 out. Furthermore, the processing unit 12 Data from the inputs and outputs 13 and 14 receive or spend. Furthermore, the processing unit has 12 Access to a memory 12 ' of the data bus subscriber 7a . 7b , ..., 7n in which, for example, data, process data, or instruction lists are stored.

The processing unit 12 may be configured to process received data and output data. Data to be processed can be received either from an upstream data bus subscriber or from inputs 13 of the data bus subscriber 7a . 7b , ..., 7n , The inputs can 13 of the data bus subscriber 7a . 7b , ..., 7n with sensors 15 be connected, for example, the measurement data, status data, etc. send. Processed data can be output either to a downstream data bus subscriber or to outputs 14 of the data bus subscriber 7a . 7b , ..., 7n , The outputs can be 14 of the data bus subscriber 7a . 7b , ..., 7n with actuators 16 be connected, for example, perform a specific action using the data directed to them. If data processing is to take place in the upward direction as well, data can also be transmitted from a downstream data bus user 7a . 7b , ..., 7n be received and processed Data to an upstream data bus subscriber 7a . 7b , ..., 7n be sent.

For the sake of simplicity, the data bus users are in the exemplary embodiment shown here 7a . 7b , ..., 7n only with one entrance 13 and an exit 14 shown and also only data bus participants 7b is with sensor 15 and actor 16 connected. However, those skilled in the art are aware that the data bus users 7a . 7b , ..., 7n a variety of inputs and outputs 13 and 14 and with a variety of different sensors 15 and actuators 16 can be connected. And that's the sensors 15 characterizing feature that the sensors 15 Record data or signals and to the data bus subscriber 7a . 7b , ..., 7n send, whereas actors 16 Data or signals from the data bus users 7a . 7b , ..., 7n receive and perform an action based on these data or signals.

Alternatively, the interfaces 8th . 9 . 10 and 11 be integrated in a module unit and the data bus users 7a . 7b , ..., 7n can be plugged onto this module unit. The module units can also be used as basic elements of the ring bus 6 be designated. The ring bus infrastructure is built up by the module units and the data bus users 7a . 7b , ..., 7n are interchangeable, so the ring bus 6 with any data bus users 7a . 7b , ..., 7n can be built. With the help of modular units is also ensured that even if a data bus subscriber 7a . 7b , ..., 7n is removed, the communication between the remaining data bus users 7a . 7b , ..., 7n is not interrupted, because the communication is done on the remaining module units.

The data bus users shown in this embodiment 7a . 7b , ..., 7n are due to their inputs and outputs 13 , 14, with sensors 15 or actuators 16 often referred to as I / O modules. Even if the data bus participants 7a . 7b , ..., 7n in the embodiment shown here as spatially separated from the sensors 15 or actuators 16 are shown, so the sensors 15 or actuators 16 also be integrated in the I / O module.

The ring bus shown in the embodiment shown here 6 is based on a cycle frame communication. A cycle frame may, for example, as a recurring (cyclic) preferably equidistant time interval in the data on the ring bus 6 are transferable. The cycle frame has, for example, at least a first identifier (SOC) and a time range for the transmission of data. Several first identifiers (SOC) of successive cycle frames are advantageously at a time equidistant from each other. The said time range is intended for the transmission of the data which can be transmitted within the cycle frame in the form of data packets. The first identifier (SOC) and the data packets are transmitted via the ring bus 6 transmit and go through all data bus users 7a . 7b , ..., 7n , Advantageously, the cycle frame is determined by the local bus master 3 in the ring bus 6 initiated. The first identifier (SOC) is separate, ie transferable as an independent symbol or advantageously contained in a start data packet (SOC packet).

Within the time range of the cycle frame, none, one or more data packets are transmitted. Advantageously, idle data (idle data) are inserted in a cycle frame, in particular adjacent to at least one data packet. Advantageously, the transmission of the data packets and / or the idle data causes an uninterrupted signal on the ring bus 6 , The signal allows the data bus users 7a . 7b , ..., 7n to synchronize on this time. Advantageously, idle data is also available at the end of the cycle frame (trailer) within a cycle frame. The trailer has a variable length and preferably follows the time range for data transmission until the next first identifier (SOC) of the next cycle frame. A corresponding cycle frame is exemplary in FIG 2 shown.

Each data packet is sent by the local bus master 3 in the downward direction to the first data bus subscriber 7a of the ring bus 6 Posted. This receives a first part of the data packet via the interface 8th , Such a part of the data packet is also referred to below as a piece, unit, or symbol. The data bus participant 7a then performs processing of the part and then passes the part to the next data bus subscriber 7b via interface 9 further, preferably simultaneously receives the first data bus subscriber 7a a second part of the data packet, etc. The size of the parts of the data packet, ie the denomination of the data packet, depends on the capacity of the data bus participants 7a . 7b , ..., 7n For example, at the same time a fixed number of bits, for example 8th Bits of the data packet at the data bus subscriber 7a . 7b , ..., 7n available. When the data transfer on the local bus 6 serial, so can the interfaces 8th and 10 be adapted to perform a serial to parallel implementation and the interfaces 9 and 11 a parallel to serial implementation. For this purpose, the interfaces 8th . 9 . 10 . 11 corresponding registers - not shown here - have. The interfaces 8th . 9 . 10 . 11 may also be adapted to perform any necessary coding and encoding. For example, an 8b10b code can be used on the local bus, its implementation by the interfaces 8th . 9 . 10 and 11 can be accomplished.

The data package goes through units, pieces, or pieces, for example, in parts or symbols of 8th Bits, the data bus users 7a . 7b , ..., 7n , The part of the data packet, which from the last data bus subscriber, in the embodiment shown here data bus users 7n , has been processed, then goes through the ring bus in the upward direction 6 so that the parts starting from the last data bus participant 7n again in the direction of local bus master 3 through all data bus users 7a . 7b , ..., 7n be sent upwards. For this, the last data bus subscriber points 7n either a switchable bridge on which the interface 9 with the interface 9 connects or to the last data bus subscriber 7n a switchable bridge - not shown here - is connected, which takes over the parts of the data packet from the interface 9 on the interface 10 to lead. Alternatively, the interface 10 of the data bus subscriber 7n also with the help of a bypass line - not shown here - directly with the interface 5b of the local bus master 3 get connected.

In the upward direction, the units of the data packet or of the data packets, as in the exemplary embodiment shown here, can be used by the individual data bus users 7a . 7b , ..., 7n back to the local bus master 3 be looped without any further processing taking place. However, it is also conceivable that processing of the units of the data packet takes place again in the upward direction, so that the data packet can be processed twice, once in the downward direction to the last data bus subscriber 7n and once in the upward direction to the local bus master 3 , For example, upstream processing may be signal refresh and / or phase shift processing.

In the processing of the data packets in the downward direction, ie by the local bus master 3 away, or in the upward direction, ie to the local bus master 3 In addition, the processing is accomplished by means of instruction lists, the instruction lists containing sets of instructions issued by the processing unit 12 of the Datenbusteilnehmer 7a . 7b , ..., 7n can be executed. The instruction lists themselves can be used by individual data bus users 7a . 7b , ..., 7n in an initialization phase from the local bus master 3 be sent or beneficial during the ongoing communication the data bus users 7a . 7b , ..., 7n be sent, so that programming the data bus participants 7a . 7b , ..., 7n without interruption of communication takes place.

Which of the instruction lists the data bus users 7a . 7b , ..., 7n It should be able to use the data bus users 7a . 7b , ..., 7n be communicated on the basis of an instruction list index. This instruction list index informs the data bus user which stored instruction list to use. An instruction list index is thus assigned to an instruction list or vice versa, so that the instruction list to be used can be identified with the aid of the instruction list index. For this purpose, the instruction list index preferably has a value which is assigned to an instruction list, for example, the value indicates a specific instruction list or its memory location. For this purpose, the value itself may be the memory address where the instruction list is stored or where at least a first instruction of the instruction list is stored. Alternatively or additionally, the value can also indicate a memory area in which the corresponding instruction list is stored. In the cases mentioned above can also be spoken of a direct assignment. The value of the instruction list index, however, can also be used, for example, as input of a look-up table (LUT). The value of the instruction list index is the input value of the conversion table. The output of the translation table may be the memory address of the first instruction in the associated instruction list or otherwise identify the instruction list. The conversion table can be stored in terms of software technology and hardware in the form of, for example, logics and specify a one-to-one conversion from an input value to an output value, the output value giving an indication of the instruction list to be used. It depends on the conversion table how a connection between the instruction list index and the instruction list is established. When using a conversion table, it is also possible to speak of an indirect assignment. In the case of direct and indirect assignment, however, the instruction list to be used by the data bus subscriber is uniquely identifiable via the instruction list index, ie can be found. The instruction list index can be inserted in the data packet before the local bus data to be processed, so that the data bus users 7a . 7b , ..., 7n according to the order of the local bus data in the data packet can use the appropriate instruction list. The instruction lists have instructions that are adapted to the order of the local bus data in the data packet. The instruction lists can be used, for example, for local bus data that is not sent to the data bus subscriber 7a . 7b , ..., 7n are addressed have a "SKIP" instruction, so the data bus subscriber 7a . 7b , ..., 7n instructing to skip the corresponding part of the data packet, whereas the instruction list for local bus data sent to the data bus user 7a . 7b , ..., 7n directed instructions may have for processing the local bus data. The data packets for sending the process data and the management data of the data bus users 7a . 7b , ..., 7n are in the 3 to 5 shown.

First, but in 2 schematically a cycle frame 17 shown. At the beginning of the cycle frame 17 is a one-to-one first identifier 18 provided as part of an SOC package (SOC - Start Of Cycle). The first identifier 18 is a bit pattern that is the beginning of the cycle frame 17 Are defined. The identifier 18 Following are several parts within the SOC package 19 . 20 . 21 . 22 of the SOC packet arranged, for example, for the control and the temporal synchronization between the local bus master 3 and the data bus users 7a . 7b , ..., 7n can be used. For example, in the SOC package is a field 19 arranged in time, in which at least one value for encryption or decryption on the local bus 6 transmitted data is present. Furthermore, the SOC packet can field one 20 have the timing of the local bus master 3 contains, so that the data bus participants 7a . 7b , ..., 7n synchronize to it. Furthermore, the SOC packet can field one 21 as a timestamp, which indicates when the first identifier 18 from the local bus master 2 was sent. The SOC packet may further include a first checksum in field 22 included, with which it can be checked if the in the boxes 19 . 20 . 21 . 22 SOC packet data received without error. Within the cycle frame 17 is also an informational time range 23 arranged in time. Within this informational time range 23 , isochronous and asynchronous data is transmitted to the data bus users. Within the cycle frame 17 can be at the end of the cycle 17 a time range (trailer) 24 be provided with idle data. The time range 24 can have a variable length and follow the information time range for data transmission. Preferably, the length of the time domain 24 until the following first identifier 18 of the next cycle frame 17 extended. Advantageously, the trailer 24 Idle data, so data that no control or regulation on the data bus users 7a . 7b , ..., 7n and still allow synchronization.

Within the informational time range 23 For data transmission, isochronous data can be contained, for example, in isochronous data packets and asynchronous data in asynchronous data packets. 3 shows an example of an isochronous data packet and the 4 and 5 each show an example of an asynchronous data packet with either a special data bus subscriber 7a . 7b , ..., 7n can be addressed or a variety of data bus users 7a . 7b , ..., 7n ,

This in 3 shown isochronous data packet 25 consists of a header, an information part and a checksum part. The header contains a box 26 which contains a one-to-one bit pattern IDE, which may also be referred to as a codeword or packet identifier. The number and design of bit patterns depend on that on the ring bus 6 used coding. It is only important that the data bus users 7a . 7b , ..., 7n from the bit pattern of the field 26 can recognize what kind of data packet it is. In the embodiment shown here, the data bus users 7a . 7b , ..., 7n Aware that if a field 26 with a bit pattern IDE is received, that this is an isochronous data packet 25 acts, the process data 28a . 28b . 28c wearing.

The header may also contain other information indicating, for example, whether the isochronous data packet 25 moved in the downward direction or upward direction. For this purpose, for example, the last data bus subscriber 7n in the header write an information that the isochronous data packet 25 already this data bus user 7n happened and was sent back towards local bus master 3 , Furthermore, the header can also contain information about the length of the isochronous data packet 25 included, so the data bus users 7a . 7b , ..., 7n the integrity of the isochronous data packet 25 or know how many parts of the isochronous data packet 25 still from the data bus user 7a . 7b , ..., 7n be received. However, the person skilled in the art also knows of other fields which are in a header of an isochronous data packet 25 may be present, for example, to control or error detection by the data bus participants 7a . 7b , ..., 7n can be used.

The information part of the isochronous data packet 25 can first get an instruction list index field 27 , ILI, which indicates which instruction list the data bus subscribers 7a . 7b , ..., 7n should use. For example, in normal operation of the ring bus 6 be provided that all data bus users 7a . 7b , ..., 7n use their first instruction list, whereas in case of error the second instruction list should be used. The instruction list index can refer to the memory location of the data bus user 7a . 7b , ..., 7n directly referenced instruction list, or the instruction list index may have a value with which the data bus subscriber 7a . 7b , ..., 7n For example, the corresponding instruction list can be found via a conversion table. Of the Information part also has the actual process data 28a . 28b and 28c on.

In the embodiment shown here is the isochronous data packet 25 in symbols of each 8th Bit divided. The isochronous data packet 25 is also used in this denomination by the data bus users 7a . 7b , ..., 7n received and processed. That is, the local bus master sends first 3 the symbol 26 to the first data bus user 7a After a predetermined time, the local bus master sends 3 another symbol of the header of the isochronous data packet 25 to the first data bus user 7a , this in turn sends the symbol at the same time 26 to the second data bus subscriber 7b in the row of data bus users 7a . 7b , ..., 7n , This predetermined time between sending and receiving the symbols of the isochronous data packet 25 , Is in an advantageous embodiment depending on a clocking of the local bus, in particular a fixed number of clocks, for example two clocks.

Furthermore, the isochronous data packet 25 in the information part still a field 29 which may be configured as a counter and that of each data bus subscriber 7a . 7b , ..., 7n through which this part of the isochronous data packet 25 already been routed could be incremented or decremented. The counter value of the field 29 can from the local bus master 3 used to check if the isochronous data packet 25 all data bus users 7a . 7b , ..., 7n has gone through.

The person skilled in the art is aware that the exemplary embodiment of the isochronous data packet illustrated here 25 is to be understood only as an example and the design of the isochronous data packet 25 otherwise it can be tailored to the needs and requirements of the particular local bus where it will be implemented.

4 shows a schematic representation of an asynchronous data packet 30 For example, for programming a data bus subscriber 7a . 7b , ..., 7n without having to interrupt the ongoing communication. The asynchronous data packet 30 can be transmitted disjointly in time to isochronous data packets in a current cyclic communication and, for example, for programming a data bus subscriber 7a . 7b , ..., 7n be used. The programming of the one data bus participant 7a . 7b , ..., 7n takes place with the help of instruction list information provided by means of the asynchronous data packet 30 at the data bus users to be programmed 7a . 7b , ..., 7n is sent.

The asynchronous data packet 30 consists of a general header, an information part and a checksum part. The header contains a box 31 which contains a unique bit pattern MWR, which may also be referred to as a codeword or identifier. The data bus participants 7a . 7b , ..., 7n have the knowledge that when the bit pattern MWR occurs, data is sent to the data bus users 7a . 7b , ..., 7n to provide. In the process, these data can just be the instruction lists for the data bus users 7a . 7b , ..., 7n be to the data bus users 7a . 7b , ..., 7n to program. Even though the instruction lists are given as an example here, the person skilled in the art is aware that other data in the asynchronous data packet is also available 30 may be included with which the data bus users 7a . 7b , ..., 7n can be programmed. The head of the asynchronous data packet 30 may also contain other information needed to control or error detection - not shown here.

The information part of the asynchronous data packet 30 includes a field 32 in which the address of the data bus subscriber to be addressed 7a . 7b , ..., 7n is deposited. Only the data bus participant 7a . 7b , ..., 7n whose address with the in the field 32 stored address reads the instruction list data 34 the information part of the asynchronous data packet 30 , The information part can also have another field 33 that of the corresponding data bus subscriber 7a . 7b , ..., 7n whose address in field 32 can be used for error detection, error propagation, or this field 33 can contain instructions to where the instruction list data 34 should be saved. The instruction list data 34 may include at least one instruction list or multiple instruction lists. After storing the instruction list or the instruction list in the respective data bus subscriber 7a . 7b , ..., 7n can also be said that the programming of the respective data bus subscriber 7a . 7b , ..., 7n is done. In this case, the instruction lists have sets of instructions which are those of the data bus users 7a . 7b , ..., 7n Define processing to be performed. For example, this is the processing that works with the process data 28a . 28b . 28c an isochronous data packet 25 to be carried out. Will the asynchronous data packet 30 before the isochronous data packet 25 within the cycle frame 17 transmit, so the data bus users 7a . 7b , ..., 7n before receiving the process data 28a . 28n . 28c This can be done, for example, in the same or in two different cycle frames. That is, before the process data 28a . 28b . 28c at the respective data bus participants 7a . 7b , ..., 7n arrive, they can be provided with information about how the process data 28a . 28b . 28c to be processed. In the embodiment shown here, the data bus users 7a . 7b , ..., 7n with the asynchronous data packet 30 each Instruction list data 34 get sent. This instruction list data 34 can in the respective data bus participants 7a . 7b , ..., 7n be stored in such a way that they can be found on an instruction list index. The isochronous data packet 25 includes an instruction list index 27 that is in each data bus participant 7a . 7b , ..., 7n indicates exactly one stored instruction list, which is used to process the process data 28a . 28b . 28c should be used.

Even if in the embodiment of the asynchronous data packet shown here 30 this over the field 32 only to one data bus user 7a . 7b , ..., 7n can be addressed, the skilled person is aware that the asynchronous data packet 30 may also have multiple addresses, broadcast or multicast addresses, such that the instruction list data 34 not just to a data bus user 7a . 7b , ..., 7n can be addressed, but to multiple data bus users 7a . 7b , ..., 7n The person skilled in the art is also aware that the exemplary embodiment of the asynchronous data packet illustrated here 30 is to be understood only as an example and the design of the asynchronous data packet 30 otherwise it can be tailored to the needs and requirements of the particular local bus where it will be implemented.

5 shows a schematic representation of another asynchronous data packet 35 For example, to query multiple data bus users 7a . 7b , ..., 7n without having to interrupt the ongoing communication. The asynchronous data packet 35 can be embedded in a sequence of data packets of the current cyclic communication.

The asynchronous data packet 35 consists of a general header, an information part and a checksum part. The header contains a box 36 which contains a unique bit pattern MRD, which may also be referred to as a codeword or identifier. The data bus participants 7a . 7b , ..., 7n have the knowledge that when the bit pattern MRD occurs, data from the data bus users 7a . 7b , ..., 7n should be read. The head of the asynchronous data packet 35 may also contain other information needed to control or error detection - not shown here.

The information part of the asynchronous data packet 35 includes two fields in the embodiment shown here 37 and 38 that can be used for control. For example, these fields may indicate which information should be queried and the priority of the asynchronous data packet 35 specify. It is clear to the person skilled in the art that any number or even no control fields can be contained in the information part.

The master sends the asynchronous data packet 35 with an area where the data bus users 7a . 7b , ..., 7n each can write their information. In the exemplary embodiment shown, the asynchronous data packet has a first field 39a in which the address of the data bus subscriber 7a . 7b , ..., 7n is. The data bus subscriber associated with the address 7a . 7b , ..., 7n , write in the box (s) below 39b the information to be sent. In the embodiment shown here, the address is in field 39a the address of the first data bus subscriber 7a , In addition, this writes in the following box 39b the information to be sent. Information of a second data bus subscriber 7a . 7b , ..., 7n can with another data packet 35 ' be queried, which, for example, in field 40a the address of the second data bus subscriber 7a . 7b , ..., 7n has to be queried from the information. The second data bus participant 7a . 7b , ..., 7n can then send his information to be sent in the field 40b Write, etc. This must be the second data bus participant 7a . 7b , ..., 7n Do not be one of the first data bus users 7a directly, but may be one that is anywhere after the first data bus subscriber, but whose address is in the field 40a contained address fits.

The person skilled in the art is aware that the exemplary embodiment of the asynchronous data packet illustrated here 35 is to be understood only as an example and the design of the asynchronous data packet 35 otherwise it can be tailored to the needs and requirements of the particular local bus where it will be implemented.

6 shows an exemplary time sequence of asynchronous and isochronous data packets 25 and 30 , such as in the 3 and 4 shown within a cycle frame 17 , such as in 2 shown. The cycle frame 17 as well as the data packages 25 . 30 , For the sake of simplicity, are each only with their one-to-one bit patterns SOC 18 for the start of the cycle frame 17 , MWR 31 for starting the asynchronous data packet 30 , IDE 26 for the start of the first isochronous data packet 25 and IDE 26 for the start of the second isochronous data packet 25 characterized. In the embodiment shown here, before the first isochronous data packet 25 which is represented by the one-bit pattern IDE 26 characterized as an asynchronous data packet 30 which is indicated by the one-bit pattern MWR 31 is marked.

With this asynchronous data packet 30 can the data bus users 7a . 7b , ..., 7n can thus be programmed, for example, with the asynchronous data packet 30 Instruction list data are sent. These data may include instruction lists, where each instruction in the list may be adapted, a processing of the following isochronous data packet 25 contained process data 28 to process.

At a time interval τ ₁ from the first bit pattern SOC 18 follows the bit pattern IDE 26 which is the isochronous data packet 25 displays. That means the local bus master 3 For example, at time t _{0, it} sends the bit pattern SOC 18 on the local bus 6 and seen at time interval τ ₁ from t _o sends the local bus master 3 the bit pattern IDE 26 and following the symbols of the isochronous data packet 25 , As the data bus participants 7a . 7b , ..., 7n are adapted so that these are the individual symbols of the cycle frame 17 have only been present for a defined predetermined time before the symbols are forwarded, and if that time on all data bus subscribers 7a . 7b , ..., 7n is constant, the first time interval τ ₁ between the bit pattern SOC changes 18 and the bit pattern IDE 26 Not. That is, if the ith data bus subscriber 7i the bit pattern SOC 18 at the time τ _i to the following data bus subscriber 7i +1, then becomes the data bus subscriber 7i also the bit pattern IDE 26 at the time τ _i + τ ₁ , etc., where i ∈ {a, ..., n}. In this case, the first time interval τ _{1 is} so from the local bus master 3 determines or determines that all symbols of the data packet 25 at the respective data bus participants 7a . 7b , ..., 7n arrived before the issue date. The output time is a time at which all data bus users 7a . 7b , ..., 7n in the isochronous data packet 25 contained process data 28 forward to their outputs 14, for example to connected actuators 16 , and all data bus users 7a . 7b , ... 7n at the same time. That is, the output time is a fixed point in time, in a certain time interval, here τ ₂ , from the transmission of the bit pattern SOC 18 through the local bus master 3 lies. The output time can be, for example, from the local bus master 3 be determined. The local bus master 3 is adapted in such a way that it is the first time interval τ ₁ , ie the time when the isochronous data packet 25 is sent, so that selects all data bus users 7a . 7b , ..., 7n their process data 28 have existed before the issue time is reached. That is, τ ₁ + τ _{data packet} ≤ τ ₂ , where τ _{data packet} indicates the duration until all data bus users 7a . 7b , ..., 7n their respective process data 28 from the isochronous data packet 25 have available for their outputs. It is well known to those skilled in the art that this duration depends on the length of the isochronous data packet 25 and / or the number of data bus users 7a . 7b , ..., 7n in the local bus 6 as well as and / or the distribution of the process data in the isochronous data packet 25 and / or depends on a duration of provision of the data within a data bus subscriber. For example, if the process data 28 of the last data bus subscriber 7n also last in the isochronous data packet 25 be transferred, this process data must first all other data bus users 7a . 7b , ..., 7n - 1 go through before this on the last data bus subscriber 7n Arrive. That means the other data bus users 7a . 7b , ..., 7n - 1 already have their process data before 28 get and have to wait until even the last data bus subscriber 7n his process data 28 is available until it can come to the issue. In this case, the duration τ _{data packet} corresponds to the time that the isochronous data packet 25 need to get the complete local bus 6 to go through. It is clear to the person skilled in the art that if the process data 28 in reverse order to the arrangement of the data bus users 7a . 7b , ..., 7n in the isochronous data packet 25 are included, the duration τ _{data packet is} the shortest. That is, if the isochronous data packet 25 as first process data 28 for the last data bus subscriber 7n contains and last but not least process data 28 for the data bus subscriber 7a Thus, in one embodiment of the invention, all data bus subscribers 7a . 7b , ..., 7n their respective process data 28 exist at the same time and not a data bus subscriber 7a . 7b , ..., 7n have to wait. This is particularly advantageous if by the data bus users 7a . 7b , ..., 7n no CRC over the entire isochronous data packet 25 must be performed. The local bus master 3 can by knowing the number of data bus subscribers 7a . 7b , ..., 7n and possibly by knowing the distribution of the process data 28 within the isochronous data packet 25 determine and select the first time interval τ _{1 in} such a way that τ ₁ + τ _{data packet} ≤ τ ₂ .

Similar to the output time, there may also be a fixed or fixed input time, ie a time at which process data 28 at the entrances 13 the data bus subscriber 7a . 7b , ..., 7n present, for example, from connected sensors 15 , The local bus master 3 can have knowledge of this point in time, from sending the bit pattern SOC 18 a third distance τ _{3 is} removed. The local bus master 3 can be adapted to another isochronous data packet 25 on the local bus 6 to send and that at a fourth time interval τ ₄ of the bit pattern SOC 18 , This further isochronous data packet 25 is doing so on the data bus participants 7a . 7b , ..., 7n before that after processing the process data 28 at the time of entry are capable of processing the processed process data 28 in each of them present symbol of further isochronous data packet 25 to write. Thus, the recorded process data 28 to the local bus master 3 transfer, which can forward this to the PLC 1 ,

In a preferred embodiment, the bit patterns become 18 . 31 . 26 Constantly delayed by each data bus subscriber. For example, the first data bus subscriber is delayed 7a the bit pattern SOC 18 around 10 Bars. The second data bus participant 7b receives the bit pattern SOC 18 corresponding to the constant delay ( 10 Clocks) later than the first data bus subscriber 7a , Thus, in an advantageous embodiment of the invention, the output time of the first data bus 7a_mit the output time of the second data bus 7b coincides clock exactly, the second distance τ ₂ differs in the first data bus 7a and second data bus users 7b in particular by exactly this constant delay ( 10 Bars). Thus, in an advantageous embodiment of the invention, the input time of the first data bus subscriber 7a with the input time of the second data bus subscriber 7b matches clock exactly, the third distance τ ₃ differs at the first data bus 7a and second data bus users 7b in particular by exactly this constant delay ( 10 Bars). The same applies to data bus users following in the transmission chain 7c etc.

In the in 6 embodiment shown, the cycle frame ends 17 before retransmission of a bit pattern SOC 18 , which is the beginning of the following cycle frame 17 displays.

Although in the in 6 As shown embodiment, the output time and the input time are given as fixed times, the skilled person is aware that the output and the input does not necessarily have to happen at a time, but can also be done in a certain period of time, which is the issue time or input time extends around.

Even if data is mentioned in the above description, the person skilled in the art is aware that the singular of data, ie a single date, should also be included here.

The components of the device according to the invention described as separate units, modules or interfaces in the described embodiment can be implemented as separate hardware, but are preferably integrated on the same semiconductor chip. Preferably, their function is implemented by hardware of logic gates. For example, the units, modules, or interfaces may be implemented on an FPGA / ASIC.

LIST OF REFERENCE NUMBERS

1

programmable logic controller (PLC)

2

higher-level bus

3

Lokalbusmaster

4

first interface

5a, b

second interface

6

ringbus

7a, b, n

Datenbusteilnehmer

8th

Input interface

9

Output interface

10

Downstream data input interface

11

Downlink data output interface

12

processing unit

13, 14

Input / Output

15

sensor

16

actuator

17

cycle frame

18

SOC codeword

19

Control data of the cycle frame

20, 21

synchronization data

22

Checksum of the header of the cycle frame

23

Information part of the cycle frame

24

trailer

25

isochronous data packet

26

IDE codeword

27

Instruction List Index

28

process data

29

count

30

asynchronous data packet

31

MRW codeword

32

address field

33

Control data of the asynchronous data packet

34

Instruction list data

35

another asynchronous data packet

36

MRD codeword

37, 38

Control data of the further asynchronous data packet

39a

first address field

39b

first data field

40a

second address field

40b

second data field

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5472347A [0010]

Claims (14)

A method of operating a local bus (6), in particular a ring bus, with data bus users (7a, 7b, ..., 7n), the method comprising: Transmitting a first identifier (18) of a cycle frame (17) over the local bus (6), the first identifier (18) defining the beginning of the cycle frame (17); Transmission of process data (28) via the local bus (6) in at least one isochronous data packet (25), wherein the at least one isochronous data packet (25) has a second identifier (26), wherein the second identifier (26) is different from the first identifier (18); Transmission of management data (34, 39b, 40b) via the local bus (6) in at least one asynchronous data packet (30, 35), wherein the at least one asynchronous data packet (30, 35) has a third identifier (31, 36), wherein the third identifier (31, 36) is different from the first identifier (18) and second identifier (26); and wherein the isochronous data packet (25) and the asynchronous data packet (30, 35) are transmitted within the cycle frame (17). The procedure according to Claim 1 wherein the at least one asynchronous data packet (30, 35) is transmitted before the at least one isochronous data packet (25). The method according to one of the preceding claims, wherein the first identifier (18) is contained in a start data packet. The procedure according to Claim 3 in which the start data packet has at least one field (19, 20, 21) and a checksum (22), wherein the at least one field (19, 20, 21) is used for controlling and / or synchronizing the timing between a local bus master (3). the local bus (6) and data bus subscribers (7a, 7b, ..., 7n) of the local bus (6) and wherein the checksum (22) is used to determine the error-free reception of the at least one field (19, 20, 21). The method of one of the preceding claims, wherein the first identifier (18), the second identifier (26) and the third identifier (31, 36) are each a one-to-one bit pattern. The method according to one of the preceding claims, wherein the management data (34, 39b, 40b) contain the programming of at least one data bus subscriber (7a, 7b, ..., 7n) of the local bus (6). The method according to one of the preceding claims, wherein the process data (28) contain data for the regulation and / or control of a process executed by at least one data bus user (7a, 7b, ..., 7n). A local bus master (3) of a local bus (6), in particular of a ring bus, with data bus users (7a, 7b, ..., 7n), the local bus master (3) having: means for transmitting a first identifier (18) of a cycle frame (17) over the local bus (6), the first identifier (18) defining the beginning of the cycle frame (17); a means for transmitting process data (28) via the local bus (6) in at least one isochronous data packet (25), wherein the at least one isochronous data packet (25) has a second identifier (26), wherein the second identifier (26) is different to the first identifier (18); a means for transmitting management data (34, 39b, 40b) via the local bus (6) in at least one asynchronous data packet (30, 35), the at least one asynchronous data packet (30, 35) having a third identifier (31, 36) wherein the third identifier (31, 36) is different from the first identifier (18) and second identifier (26); and wherein the isochronous data packet (25) and the asynchronous data packet (30, 35) are transmitted within the cycle frame (17). The local bus master (3) to Claim 8 wherein the means for sending the first identifier (18), the means for transmitting the process data (28) and the means for sending management data (34, 39b, 40b) is the same means for transmitting. A data bus subscriber (7a, 7b, ..., 7n), in particular a ring bus, wherein the data bus subscriber (7a, 7b, ..., 7n) has: means for receiving a first identifier (18) of a cycle frame (17) via the local bus (6), the first identifier (18) defining the beginning of the cycle frame (17); a means for receiving at least one isochronous data packet (25), the at least one isochronous data packet (25) having a second identifier (26), the second identifier (26) being assigned to the data bus subscriber (7a, 7b, ..., 7n) indicating that the received isochronous data packet (25) includes process data (28); and a means for receiving at least one asynchronous data packet (30, 35), the at least one asynchronous data packet (30, 35) having a third identifier (31, 36), the third identifier (31, 36) being assigned to the data bus user (7a, 7b, ..., 7n) indicates that the received asynchronous data packet (30, 35) includes management data (34, 39b, 40b). The data bus subscriber (7a, 7b, ..., 7n) after Claim 10 in which the means for receiving the first identifier (18), the means for receiving at least one isochronous data packet (25) and the means for receiving at least one asynchronous data packet (30, 35) is the same means for receiving. The data bus subscriber (7a, 7b, ..., 7n) according to one of Claims 10 or 11 , further comprising: means for transmitting the received first identifier (18) to a subsequent data bus subscriber (7a, 7b, ..., 7n) after a predetermined time after receipt; means for transmitting the at least one received isochronous data packet (25) to the subsequent data bus subscriber (7a, 7b, ..., 7n) after a predetermined time after receipt; means for transmitting the at least one asynchronous data packet (30, 35) to the subsequent data bus subscriber (7a, 7b, ..., 7n) after a predetermined one after the reception. The data bus subscriber (7a, 7b, ..., 7n) after Claim 12 wherein the means for transmitting the received first identifier (18), the means for transmitting the at least one received isochronous data packet (25) and the means for transmitting the at least one asynchronous data packet (30, 35) is the same means for transmitting. The data bus subscriber (7a, 7b, ..., 7n) according to one of Claims 10 to 13 , further comprising: means for processing the identified process data (28).

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