DE102017012228B4 - Module unit - Google Patents

Abstract

A module unit (8a, 8b, 8n) for connecting a data bus subscriber (20a, 20b, ..., 20n) to a local bus (6, 7) is described, the module unit (8a, 8b, 8n) has a first input interface ( 9) and a first output interface (10) connectable to the local bus (6, 7), a first data connection interface (14b) connectable to the data bus subscriber (20a, 20b, ..., 20n), and a first switching means (23) that is adapted depending on a control input, St, from the data bus subscriber (20a, 20b, ..., 20n) to assume a first or a second switching state, and in the first switching state the first input interface (9) with the first output interface (10) to connect and to connect the first data connection interface (14b) to the first output interface (10) in the second switching state.

Description

Field of the Invention

The present invention relates to a module unit for connecting a data bus subscriber to a local bus, in particular during the operation of the local bus.

State of the art

Module units for connecting a data bus subscriber to a local bus are mostly used in automation systems. Automation systems are used in particular to control industrial systems, buildings and means of transport. Multiple sensors and actuators are usually required to control an automation system. These monitor and control the process carried out by the system. The different sensors and actuators of an automation system are often also referred to as automation devices.

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

The control of an automation system is usually carried out with the help of one or more programmable logic controllers, PLC , accomplished. The PLCs can be arranged hierarchically or decentrally in an automation system. There are with the PLC Different performance classes so that they can take on different controls depending on the computing and storage capacity. A PLC In the simplest case it has inputs, outputs, an operating system (firmware) and an interface via which a user program can be loaded. The user program determines how the outputs are to be switched depending on the inputs. The inputs and outputs can be connected to the automation devices and / or the I / O modules and the process that is carried out by the automation system can be monitored or controlled using the logic stored in the user program. The process is monitored by the sensors and the process is controlled by the actuators. The controller can also be referred to as a central controller or central unit and takes over control for 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 is in the form of parallel wiring, i.e. One line from each automation device or each I / O module is routed to the higher-level control, very complex. Especially when the degree of automation of an automation system increases, the cabling effort with parallel wiring increases. This is associated with great effort in project planning, installation, commissioning and maintenance.

For this reason, bus systems with which the automation devices or the I / O modules can be connected to the controller are mostly used in automation technology. 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 are often first connected to one another with the help of a specialized local bus and then at least one Participants of this local bus connected to the bus system, which is connected to the controller. The local bus system can differ from the bus system that is used to establish the connection to the controller.
The subscriber of a group of local bus subscribers connected to the control bus system is often also referred to as the local bus master. Alternatively, the term head station of the local bus system is also used. Compared to other local bus participants, this local bus master can contain further logic, circuits or functionalities that are necessary for connection to the bus system of the controller. The local bus master can also do one PLC include. This subscriber can also have logic and circuits for implementation between the two bus systems. The local bus master can therefore also be designed as a gateway or bus converter and ensures that the data in the format of one bus system is converted into the format of the local bus system and vice versa. But mostly not mandatory, the local bus master specializes in connecting the local bus to the higher-level bus.

The local buses used are mostly tailored to the special application requirements of the automation devices or I / O modules or take their special hardware design into account. The groups of automation devices or I / O modules of the local bus system mostly form a sub-group of the automation system for performing a special task in the process carried out by the automation system. The data for the process exchanged on the buses are also often referred to as local bus data or process data because this data contains information for regulating or controlling the process carried out by the automation system. These data can include measurement data, control data, status data and / or other information. Depending on the bus protocol used, this data can be preceded by other data (header) or appended (trailer). This other data may include information related to the data or information related to internal communication on the local bus. A large number of different pieces of information are known, which can be preceded or added to the process data according to the bus protocol used. The local bus devices connected to a local bus can also be referred to as data bus devices because they exchange data on the local bus. A data bus subscriber can be used to control or monitor a process, in particular by outputting control signals, for example to actuators, and / or by receiving measurement signals, for example from sensors. The data bus participant converts the control signals and / or measurement signals into process data for the local bus or vice versa.

An example of a local bus is a ring bus, which is a specialized form of the local bus, such as from US 5,472,347 A known. In a ring bus, the data bus subscribers, for example the automation devices or I / O modules, are each connected to their directly adjacent data bus subscribers, and data are forwarded in sequence from one data bus subscriber to another. The data are therefore not sent to all the data bus subscribers simultaneously, but in sequence, a data bus subscriber receiving data from its upstream data bus subscriber and forwarding data to its downstream data bus subscriber. Between the receipt of the data and the forwarding, the data bus subscriber can process the received data. When the data has reached the last data bus subscriber in the row, the data from the last data bus subscriber are routed back in turn back to the first data bus subscriber. The return can either be done by all data bus participants or bypass them with the help of a bypass line. The ring bus thus has a downward and upward stream of data. The data in a ring bus is usually transmitted in the form of data packets that all data bus participants pass through.
In a closed ring bus arrangement, it is necessary that each slot of the local bus is occupied by a data bus participant, so that data can be forwarded in sequence from one data bus participant to another. If a slot is not occupied by a data bus participant, the bus or the downward current and / or the upward current is interrupted and forwarding or returning the data no longer works. Removing an appropriately plugged-in data bus subscriber during operation would also interrupt the bus immediately.

Proceeding from this, it is the object of the present invention to provide an improved module unit which enables a local bus not to be interrupted, but to continue to be operated even when one or more data bus subscribers are removed.

Summary of the invention

This object is achieved with a module unit according to the independent claim. Advantageous embodiments are described in the subclaims.

The module unit according to the invention for connecting a data bus subscriber to a local bus, in particular a ring bus, has a first input interface and a first output interface which can be connected to the local bus. This means that the first input interface and a first output interface are adapted to be connected to the local bus. The module unit according to the invention also has a first data connection interface which can be connected to the data bus subscriber. Ie the data connection interface is adapted to be connected to the data bus subscriber. Furthermore, the module unit according to the invention has a first switching means that is adapted to assume a first or a second switching state depending on a control input from the data bus subscriber, the first input interface being connected to the first output interface in the first switching state and the second one assumed switching state, the first data connection interface is connected to the first output interface. That is, depending on the switching state of the switching means, either the first input interface is connected to the first output interface and data is only passed through the module unit, whereas in the other switching state, data which are present at the first input interface are not passed directly to the first output interface, but rather the data the first output interface are dependent on the first Data connection interface, that is to say, for example, of the data that the data bus subscriber provides on this first data connection interface. For example, the switching means can be adapted to adjust the respective switching states according to whether a data bus subscriber is connected to the module unit or not. In the event that no data bus subscriber is connected to the module unit, the switching means can, for example, establish the first switching state, whereas the switching means, in the event that a data bus subscriber is connected to the module unit, can produce the second switching state.

The module unit according to the invention allows a data bus subscriber to be removed from the local bus or a data bus subscriber to be added without the local bus being interrupted for a long time. It is particularly advantageous in the module unit according to the invention that the downward stream of data is not interrupted, even if a data bus subscriber is added or removed, because in this case the module unit still establishes a connection between the first input interface and output interface.

In a preferred embodiment of the module unit according to the invention, it has a second data connection interface which can be connected to the data bus subscriber - that is to say is adapted to be connected to the data bus subscriber -, the first switching means being further adapted to connect the second data connection interface to the first input interface. I.e. the data which are present at the first input interface are passed to a second data connection interface, so that these can be passed on to the data bus subscriber, who can then process them. The data bus subscriber can then output the processed data on the first data connection interface, which is connected to the first output interface, so that the processed data can be forwarded to the next module unit or the next data bus subscriber. The switching means can establish the connection between the second data connection interface and the first input interface in the same switching state in which the first data connection interface is also connected to the first output interface. However, it is also conceivable that the connection between the second data connection interface and the first input interface is established in a switching state before or after the first switching state. I.e. the connection of the first data connection interface to the first output interface can be established simultaneously with the connection of the second data connection interface to the first input interface, or the corresponding connections can be established in succession. The data sent on the local bus can be transmitted in the form of data packets. The data packets can also be called telegrams. A data packet has, for example, header, payload and advantageously a checksum.

In a further preferred embodiment of the module unit according to the invention, the local bus is designed as a ring bus and the first input interface is adapted for receiving data, whereas the first output interface is adapted for sending data. The first input interface receives data from an upstream data bus subscriber or an upstream module unit or the local bus master. The output interface sends data to a downstream data bus subscriber or a downstream module unit. Receiving and sending can be passive or active. I.e. for example, the reception may consist solely in that a signal is present at the first input interface, but no signal processing takes place. In this case one can speak of passive reception. In the event that signal processing takes place, for example, active reception can be spoken of. The same applies to transmission, if no signal processing is carried out, i.e. the signal is therefore simply provided at the first output interface, so passive transmission can be spoken of, whereas if signal processing is being carried out, active transmission can be spoken of. The first input interface and the first output interface can both be passive or active, i.e. perform no or signal processing, or one of the two interfaces can be active whereas the other is passive, i.e. one performs signal processing, while the other does not perform signal processing. The person skilled in the art is aware that the term signal processing can mean any processing of a signal, for example coding, decoding, applying modulation or de-modulation, conversion to or from a transmission format into another format, etc. Here are the corresponding ones Signal processing for the conversion of wired signals to wireless signals includes. In a ring bus, the data is sent in the form of data packets that all data bus participants pass through. Data packets are sent from the local bus master to the data bus participants within a cycle frame.

A cycle frame can, for example, be a recurring (cyclical), preferably equidistant, time interval in which data is stored are transferable to the local bus. The cycle frame has, for example, at least one start identifier (SOC) and a time range for the transmission of data. Several start identifiers (SOC) of successive cycle frames are advantageously at a time-equidistant distance from one another. The stated time range is intended for the transmission of the data packets. The start identifier (SOC) and the data packets are transmitted via the local bus and pass through all data bus participants. The start identifier (SOC) is separate, that is to say transferable as an independent symbol or advantageously contained in a start data packet (SOC packet).

No, one or more data packets are transmitted within the time frame of the cycle frame. Idle data is advantageously inserted in a cycle frame, in particular adjacent to at least one data packet. The transmission of the data packets and / or the idle data advantageously causes an uninterrupted signal on the local bus. The signal enables the data bus participants to synchronize in time with it. The cycle frame advantageously also has a trailer. The trailer has a variable length and preferably follows the time range for data transmission until the next start identifier (SOC) of the next cycle frame. The trailer advantageously has idle data.

The data packets transmitted in the cycle frame are preferably originally generated by the local bus master and sent to the data bus participants via the ring bus. When generating, the local bus master can be controlled by the controller, for example one PLC , insert received process data into a data packet. The data packet can also contain process data from the local bus master itself and / or the controller. The data packet and thus the process data contained therein then step through the individual data bus participants of the ring bus. The data packet can have a large number of symbols, each symbol having a specific number of bits, for example 8 bits, ie 1 byte. The data packet accordingly runs through the data bus participants in units, pieces or parts, for example in the form of symbols. Accordingly, the data bus subscribers always have only part of the data packet at any given time. So when we are talking about data, this can also mean a symbol of the data packet that is currently going through the ring bus. A data packet that carries process data can also be referred to as a process data packet. The process data packet has the process data that are sent and / or received by the data bus participants of the local bus. The process data packet advantageously has no address for transmitting the process data to or from a data bus subscriber in the local bus. The process data are arranged in the process data packet in such a way that, based on the respective position of the process data in the process data packet, data bus subscribers, for example one or more bits within an associated coherent data block ( 1 Byte) which process data belonging to the respective data bus participant can recognize. The process data packet advantageously has an identifier (IDE) which is assigned to the type of the data packet, that is to say the process data packet, and which can be identified by the data bus subscriber.

However, a data packet can also be a communication data packet which has no process data and is used in particular for programming and / or for controlling and / or for monitoring and / or for identifying at least one data bus subscriber. The communication data packet advantageously has an address which is assigned to at least one data bus subscriber. The data bus subscriber is preferably set up to evaluate the address and to process the communication data packet accordingly.

In a further preferred embodiment of the module unit according to the invention, the first input interface has at least one detachable electrical contact for connection to the local bus and / or the first output interface has at least one detachable electrical contact for connection to the local bus. Signals can be received from the upstream data bus subscriber or the upstream module unit via the one electrical contact of the first input interface, and signals can be sent via the one electrical contact of the first output interface to the downstream data bus subscriber or the downstream module unit. Sending and receiving can be done passively or actively. The person skilled in the art is also aware that the interfaces can also have a different number of contacts and the number is only dependent on the specific design of the local bus. The person skilled in the art is also aware that the contacts can be designed as plug-in, cutting or other contacts with which an electrically conductive connection can be established. It is also conceivable that an optical connection is established. The fact that the contacts are detachable means that they do not form a firm connection, but can be detached from one another by exerting a certain force.

In a further preferred embodiment of the module unit according to the invention the first data connection interface and / or the second data connection interface each have at least one detachable electrical contact for connection to the data bus subscriber. In this case, the second data connection interface can be adapted to send signals to the data bus subscriber via the contact, wherein this transmission can take place passively or actively, and the first data connection interface can be adapted to receive signals from the data bus subscriber, whereby this reception can take place passively and actively. The person skilled in the art is also aware that the interfaces can also have a different number of contacts and the number depends only on the specific design of the data bus participants. The person skilled in the art is also aware that the contacts can be designed as plug-in, cutting or other contacts with which an electrically conductive connection can be established. It is also conceivable that an optical connection is established.

In a further preferred embodiment of the module unit according to the invention, this has at least one connecting element in order to be connected to a further module unit, the first output interface of the module unit being electrically connected to a first input interface of the further module unit, or the first input interface of the module unit being electrically connected with a first output interface of the further module unit. The connecting element can establish a mechanical connection between the two module units, the connection being releasable only by applying a certain force. Accordingly, it can also be said that the connecting element is a mechanical connecting element. The mechanical connecting element can be formed, for example, in that the module units have latching hooks on one side and recesses or undercuts on the opposite side, so that when two module units are arranged on one another, the latching hooks of one module unit into the recesses or the undercuts of the other module unit grip so that they can be mechanically but releasably connected. However, other possibilities are known to the person skilled in the art of how two module units can be mechanically detachably connected to one another and which geometries must be arranged on the module units for this purpose. When connecting the module units, the connecting element is designed such that when the module units are connected, the interfaces are also electrically connected. The first output interface of one module unit is electrically connected to the first input interface of the other downstream module unit. The connecting element then ensures that the module units can only be detached from one another again by applying a certain force which exceeds the holding force of the connecting element, and the electrical connections are thus detached again. The module units can also be adapted in such a way that they can be arranged next to one another on a top-hat rail and the connecting element can be designed in such a way that it fixes the module unit on the top-hat rail, so that a further module unit with its connecting element is fixed directly to the one on the top-hat rail Module unit can be fixed. This allows several module units to be strung together and fixed to the top-hat rail. In this case, the at least one contact of the first output interface of the one module unit can be brought into contact with the first input interface of the downstream directly adjacent module unit in order to establish an electrical connection.

In a further preferred embodiment of the module unit according to the invention, this has at least one connection element in order to be connected to a data bus subscriber, the first data connection interface and / or the second data connection interface being electrically connected to the data bus subscriber. The connecting element can at least be designed in such a way that it allows detachable mechanical connection of the data bus subscriber to the module unit. For example, this can be achieved by means of suitable plug-in or clamp connection elements on the module unit and on the data bus device, so that the data bus device can only be released from the module unit when a holding force provided by these elements is applied. It is also conceivable that security elements are used which prevent the data bus subscribers from being unintentionally released, for example in the event of strong vibrations. These securing elements can, for example, be released only with a tool or represent an additional holding force. If the data bus subscriber is connected to the module unit, then the first and / or second data connection interface are also connected to the data bus subscriber, which has corresponding complementary contacts. This can be done with the appropriate plug or clamp contacts.

In a further preferred embodiment of the module unit according to the invention, it has a second input interface and a second output interface for connecting to the local bus. These interfaces form the uplink of the local bus and allow signals from a downstream data bus subscriber or a downstream module unit at the second input interface are received to be sent to an upstream data bus subscriber or module unit via the second output interface. Sending and receiving can be done passively or actively. In a simple embodiment, the module unit can have a direct electrically or optically conductive connection between the second input interface and the second output interface. In other words, in this configuration, the data are only passed through the module unit in the upward direction. Alternatively, the module unit can also have a third and a fourth data connection interface for connecting to the data bus participant, and a second switching means, which is adapted to assume a first or a second switching state depending on the control input from the data bus participant, and the second in the first switching state To connect input interface to the second output interface and in the second switching state to connect the third data connection interface to the second input interface and / or to connect the fourth data connection interface to the second output interface. In this embodiment, signals coming from the downstream data bus subscriber or the downstream module unit can also be processed by the data bus subscriber in the upward direction. This has the advantage, in particular in a ring bus, that the symbols of the data packet passing through the data bus subscriber can be processed twice, namely once when they are sent in the downward direction and the second time when they are sent in the upward direction.

In a further preferred embodiment of the module unit according to the invention, the first and / or second switching means are electrically controllable. I.e. the control input is an electrical signal and, in accordance with the electrical signal, the first and / or second control means assume a corresponding switching state. The wording “the first and / or the second switching means” means that at least one of the switching means is configured in this way. If there is only a first switching means, this is designed in this way. If the module unit has multiple switching means, at least one switching means is designed in this way, but preferably all switching means are configured in this way. Both switching means can be acted upon by the same control signal, so that both switching means can be controlled simultaneously, or the switching means can be acted upon with different control signals. The control signal can, for example, be generated by the data bus subscriber itself and can only be generated when a certain condition has been met. For example, both switching means can initially be in the first switching state, that is to say provide signals in a downward and upward direction. If the data bus subscriber is connected to the module unit, the latter can, for example, immediately provide a control signal, which causes the switching means to switch to the second switching state, so that the signals are no longer routed past the data bus subscriber, but can be processed by the latter. However, it may also be the case that the data bus subscriber first takes a certain amount of time until it is ready for communication or processing, and a control signal is only sent to the module unit after this time, so that only when the communication or the processing is ready, the data is routed to the data bus subscriber. The control signal itself can be any signal that is able to convey information from the data bus subscriber to the switching means. For example, this information can be transported by means of an electrical or optical signal. The control signal can be a binary signal, for example, which only indicates whether or not a switching state is to be assumed. The first and / or the second switching means can be at least one electromechanical switch. For example, the first and / or the second switching means can be a relay with an electromagnet, which is designed such that the electrical control signal can actuate the relay. The electromechanical switch can be located in or on the module unit. The first and / or the second switching means can alternatively also be an electronic switch. The switch can be implemented in the form of a semiconductor component, for example by means of a field effect transistor, bipolar transistor or by means of a diode circuit. The electronic switch can be switched by means of the electrical control signal. Electronic switches advantageously have a shorter switching time than electromechanical switches and are also free of bounce and wear. The electronic switch can also be located in or on the module unit.

In a further preferred embodiment of the module unit according to the invention, the first and / or second switching means can be controlled mechanically. Ie the control input is a mechanical input and, according to the input, the first and / or second control means assume a corresponding switching state. That is, the switching means are mechanically transferred from the first to the second switching state. For example, this can be done by means of a geometry arranged on the data bus subscriber which, when the data bus subscriber is arranged on the module unit, switches the switching means or the switching means from a first switching state to a second switching state. If the data bus subscriber with the corresponding geometry is then removed again, the switching means or the switching means can go back again are transferred from the second switching state to the first switching state. For this purpose, the geometry can be designed in the form of a pin, for example, in order to change the switching state in a correspondingly designed switching means.

In a further preferred embodiment of the module unit according to the invention, the first and / or second switching means can be controlled optically. I.e. the control input is an optical signal and, in accordance with the signal, the first and / or second control means assume a corresponding switching state.

In a further preferred embodiment of the module unit according to the invention, the first switching means and / or the second switching means are adapted to assume the first switching state when there is no control input, in particular when no data bus subscriber is connected to the module unit. I.e. if no data bus subscriber is connected to the module unit, there is no control signal or there is no geometry which causes a switching state. In this case, the first switching state is preferred, which allows the signals on the local bus to be passed through in the downward and upward direction. In this case, the module unit provides a pass-through. For example, this can be done by establishing a low-resistance path or a conductive path between the input and output interfaces.

In a further preferred embodiment of the module unit according to the invention, the first switching means and / or the second switching means in the first switching state are adapted to connect the second data connection interface and / or the third data connection interface to a fixed potential. I.e. a reference potential is created.

In a further preferred embodiment of the module unit according to the invention, it can have a housing made of plastic or another non-conductive material, so that the interfaces are electrically insulated from the environment. The housing can, for example, be adapted to accommodate the data bus subscriber. Furthermore, the housing can be adapted to fix the module unit on a top-hat rail.

In a further preferred embodiment of the module unit according to the invention, the module unit has a voltage connection interface for connecting a voltage source to the data bus subscriber. The voltage connection interface can be designed similarly to the data connection interfaces, so that a detachable connection of the data bus subscriber to the module unit is possible. The voltage connection interface supplies the data bus device with mains voltage, so that the data bus device can be operated. The associated voltage source can be located in or on the module unit or can be arranged outside the module unit.

In yet another preferred embodiment of the module unit according to the invention, the module unit has a control input interface for receiving the control input from the data bus subscriber. The control input interface, like the data connection interface and the voltage connection interface, can also be pronounced, so that it enables a detachable connection of the data bus subscriber to the module unit.

Figure list

• 1 ein schematisches Blockdiagramm einer beispielhaften Automatisierungsanlage mit einer speicherprogrammierbaren Steuerung, einem übergeordneten Bus, einem Ausführungsbeispiel der erfindungsgemäßen Moduleinheit, sowie einen beispielhaften Ringbus;
• 2 ein schematisches Schaltdiagramm eines Ausführungsbeispiels der erfindungsgemäßen Moduleinheit ohne einen daran angeordneten Datenbusteilnehmer mit den Schaltmitteln in dem ersten Schaltzustand; und
• 3 ein schematisches Schaltdiagramm eines Ausführungsbeispiels der erfindungsgemäßen Moduleinheit mit einem daran angeordneten Datenbusteilnehmer mit den Schaltmitteln in dem zweiten Schaltzustand.

The invention is explained in more detail below using exemplary embodiments with the accompanying drawings. Further details, features and advantages of the subject matter of the invention result from the exemplary embodiments described. Show it:

• 1 a schematic block diagram of an exemplary automation system with a programmable logic controller, a higher-level bus, an exemplary embodiment of the module unit according to the invention, and an exemplary ring bus;
• 2nd a schematic circuit diagram of an embodiment of the module unit according to the invention without a data bus device arranged thereon with the switching means in the first switching state; and
• 3rd a schematic circuit diagram of an embodiment of the module unit according to the invention with a data bus device arranged thereon with the switching means in the second switching state.

Description of preferred embodiments

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

In the 1 Automation system shown has a higher-level control 1 on the for example with a programmable logic controller, PLC , can be realized. Such one PLC 1 basically serves to control and regulate the process carried out by the automation system. Take over nowadays PLCs 1 in automation systems, however, also additional functions, such as the visualization, alarming and recording of all data relating to the process, and that is how the functions PLC 1 as a human-machine interface. There are PLC 1 in different performance classes, which have different resources (computing capacity, storage capacity, number and type of inputs and outputs, and interfaces) that the PLC 1 enable the process of the automation system to be controlled and regulated. A PLC 1 usually has a modular structure and consists of individual components, each with a different task. Usually there is one PLC 1 from a central computing module (with one or more main processors and memory modules) and several modules with inputs and outputs. Such a modular structure PLC 1 can be easily expanded by adding modules. 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 that is PLC 1 also mostly no longer an independent system, but the PLC 1 is connected to the Internet or intranet via appropriate interfaces - not shown here. This means that PLC 1 is part of a network via which or from which PLC 1 Can receive information, instructions, programming, etc. For example, the PLC 1 receive information about materials fed into the process via a connection to a computer located on the intranet or Internet, so that the process can be optimally controlled, for example, by knowing its number or nature. It is also conceivable that the PLC 1 is controlled by a user through access from the intranet or Internet. For example, a user can use a computer, also called a host computer, to access the PLC 1 access and check, change or correct their user programming. Accordingly, access to the PLC 1 possible from one or more remote control centers or control centers. The master computers can optionally have visualization devices for displaying process sequences.

To control the process of the automation system is the PLC 1 connected to automation devices. In order to keep the wiring effort low, bus systems are used for these connections. In the in 1 The embodiment shown is the PLC 1 by means of a superordinate bus 2nd , which can be a fieldbus in the exemplary embodiment shown here, with a local bus master 3rd a subordinate local bus system. To the parent bus 2nd can not only a local bus master as in the embodiment shown here 3rd a local bus, but also any other participants - not shown here - who are used to communicate with the PLC 1 are designed.

The parent bus 2nd is in the embodiment shown here with the local bus master 3rd connected. The local bus master indicates this 3rd a first interface 4th on, which is designed so that this with the higher-level bus 2nd can be connected. the interface 4th can have, for example, a receptacle in the form of a socket and the higher-level bus 2nd can have a plug that can be received by the socket. The plug and the socket can be, for example, a modular plug and a modular socket, ie each wire of the higher-level bus 2nd is connected electrically or optically with a connection in the modular socket. However, other possibilities are known to the person skilled in the art, such as an interface 4th must be designed so that the local bus master 3rd electrically or optically with the higher-level bus 2nd can be connected. The person skilled in the art is familiar with screw, rotary, click or plug connections with the aid of which an electrical or optical connection can be established. A male connector is usually received by a female counterpart. This recording usually not only establishes the electrical or optical connection, but also ensures that the two parts are mechanically coupled and can only be detached from one another with the application of a certain force. But it is also conceivable that the parent bus 2nd firmly with the interface 4th is wired.

The local bus master 3rd in the exemplary embodiment shown here has a further second interface to the local bus master 3rd to connect to the local bus. the local bus in the exemplary embodiment shown here as a ring bus 6 is designed. In this case, 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 forth and the second part 5b the second interface provides the uplink in the ring bus 6 forth.

The ring bus 6 whose data transmission direction is indicated by arrows in the 1 shown exemplary embodiment, has several module units in the embodiment shown here 8a , 8b , ..., 8n for connection to data bus participants 20a , 20b , ..., 20n on.

A data packet sent by the local bus master 3rd on the local bus 6 is sent runs through all module units 8a , 8b , ..., 8n and data bus subscribers connected to them 20a , 20b , ..., 20n . A data bus participant receives 20a , 20b , ..., 20n from its upstream data bus subscriber 20a , 20b , ..., 20n or a module unit 8a , 8b , ..., 8n only part of the data packet. After a period of time in which the data contained in this part from the data bus participant 20a , 20b , ..., 20n can be processed, the part is sent to the downstream data bus subscriber 20a , 20b , ..., 20n is forwarded and at the same time by the upstream data bus subscriber 20a , 20b , ..., 20n or module unit 8a , 8b , ..., 8n received a new part of the data packet. In this way, all parts of the data packet sequentially pass through all data bus participants 20a , 20b , ..., 20n or module units 8a , 8b , ..., 8n . The local bus is advantageously designed in an annular structure. Such local buses can also be used as ring buses 6 be designated. The local bus can alternatively also be in the form of a line or star or of a combination or mixed form of the aforementioned. The modular units 8a , 8b , ..., 8n can also be used as basic elements of the ring bus 6 be designated. The ring bus infrastructure is provided by the module units 8a , 8b , ..., 8n established and the data bus participants 20a , 20b , ..., 20n are interchangeable, so the ring bus 6 with any data bus participants 20a , 20b , ..., 20n can be built. With the help of the modular units 8a , 8b , ..., 8n it is also ensured that even if a data bus participant 20a , 20b , ..., 20n the communication between the remaining data bus participants is removed 20a , 20b , ..., 20n is not interrupted because the communication via the still existing module units 8a , 8b , ..., 8n happens.

The modular units 8a , 8b , ..., 8n each have a first input interface in the exemplary embodiment shown here 9 on to data from one on the ring bus 6 upstream or preceding subscribers, for example an upstream module unit, a data bus subscriber, or a local bus master 3rd to recieve. The reception can be active or passive, ie signal processing can take place or not. In the case of the module unit shown 8a , receives this via the first input interface 9 Data from the upstream local bus master 3rd . Furthermore, the module units have 8a , 8b , ..., 8n in the exemplary embodiment shown here a first output interface 10th to forward data to a downstream or subsequent module unit and / or data bus subscriber. In the case of modular unit 8a , sends this data to the downstream module unit 8b with the attached data bus participant 20b via the first output interface 10th . Sending can be active or passive, ie signal processing can take place or not. The first input interface 9 and the first output interface 10th serve to propagate data in the downward direction of the ring bus 6 , ie from the local bus master 3rd path. Furthermore, the module units have 8a , 8b , ..., 8n also a second input interface 11 and a second output interface 12 on the propagating data in the upward direction of the ring bus 6 serve, ie to the local bus master 3rd there. In the case of the modular unit 8a is the second input interface 11 designed to receive data from the downstream or subsequent module unit 8b with or without a data bus device arranged on it 20b to receive and the second output interface 12 is designed to send data to the preceding module unit and / or the upstream data bus subscriber, here the local bus master 3rd to forward. It can thus be said that the output interfaces 10th and 12 Transmitter interfaces are, whereas the input interfaces 9 and 11 Are receiver interfaces.

Even if the local bus master 3rd and the individual module unit 8a , 8b , ..., 8n with or without attached data bus participants 20a , 20b , ..., 20n are shown spaced apart from one another in the exemplary embodiment shown here, the local bus master 3rd also decentralized from the module unit 8a , 8b , ..., 8n , be arranged. As the expert knows, the module unit 8a , 8b , ..., 8n and the local bus master 3rd - who is also a data bus participant of the ring bus 6 represents - can also be directly connected to each other. For example, contacts of one module unit 8a , 8b , ..., 8n into corresponding receptacles or receptacle contacts of a directly adjacent module unit 8a , 8b , ..., 8n grip, so as an electrical or optical connection between the module units 8a , 8b , ..., 8n so that data can be sent in the downward and upward directions. For example, the module units 8a , 8b , ..., 8n have receptacles on the side facing away from the master and contacts on the side facing the master. Become the modular units 8a , 8b , ..., 8n then lined up accordingly, the contacts of one module unit engage 8a , 8b , ..., 8n each in the recordings of the other module unit 8a , 8b , ..., 8n and an electrical or optical connection can be made. The local bus master 3rd then has corresponding receptacles on the side, in the contacts of the first module unit 8a grab, so between the interfaces 5a and 9 or the interfaces 5b and 12 to create an electrical or optical connection. However, other possibilities are known to the person skilled in the art, for example pressure contacts, knife and fork contacts, such as two module units arranged directly next to one another 8a , 8b , ..., 8n can make an electrical or optical connection. Can too in the 1 module units shown separately 8a , 8b , ..., 8n be arranged in a common housing so that their respective first and second input and output interfaces 9 to 11 , are connected to each other inside the housing, for example by means of conductor tracks.

In the event that the modular units 8a , 8b , ..., 8n and the local bus master 3rd If they are to be connected directly to one another, they can also have mechanical receptacles or mechanical connecting elements with which the individual module units 8a , 8b , ..., 8n and the local bus master 3rd can be connected to each other. Here, for example, a module unit 8a , 8b , ..., 8n have a projection on one side and an undercut on the other side. Become the modular units 8a , 8b , ..., 8n then strung together, a projection engages in an undercut of the other module unit 8a , 8b , ..., 8n so that a mechanical coupling is created. For simply lining up the module units 8a , 8b , ..., 8n these can also be arranged on a common receptacle, for example a top-hat rail. The module units can be attached to the top-hat rail 8a , 8b , ..., 8n have appropriate fasteners. Alternatively or additionally, the module units 8a , 8b , ..., 8n also have, for example, releasably connectable fastening means with which the module units 8a , 8b , ..., 8n can either be attached to the DIN rail or to another receptacle. For this purpose, the releasably connectable fastening means can be exchangeable and a corresponding fastening means for the desired receptacle can be used with the module units 8a , 8b , ..., 8n be connected so that they can be attached to the desired receptacle.

The on the module units 8a , 8b , ..., 8n attachable or attachable data bus participants 20a , 20b , 20n , connect via data connection interfaces 13a , 14a , 15a , 16a with corresponding data connection interfaces 13b , 14b , 15b , 16b on the module units 8a , 8b , ..., 8n .

The data connection interfaces 13b , 14b , 15b , 16b on the module units 8a , 8b , ..., 8n are in turn with the first and second input and output interfaces 9 , 10th , 11 , 12 connected. The data bus participants 20a , 20b , 20n have, for example, an arithmetic-logic unit or another type of arithmetic kernel that can be used to process data. This processing unit can be a processor, a microcontroller or a computing circuit, which can be formed in particular from gate elements of an integrated circuit. The arithmetic circuit can be designed as digital logic, which is in particular formed at least as part of a semiconductor chip. The circuits can be implemented in an application-specific integrated circuit (ASIC) or in a field programmable (logic) gate arrangement (FPGA). The data bus participants 20a , 20b , 20n can be designed to receive data from the ring bus 6 to process and output data. The data to be processed can either be received by an upstream data bus participant 20a , 20b , 20n , the local bus master 3rd or from participant entrances 21st of the data bus subscriber 20a , 20b , 20n . The participant entrances 21st of the data bus subscriber 20b can be connected to sensors that send, for example, measurement data, status data, etc. Processed data can either be output to a downstream data bus subscriber 20n or at the participant exits 22 of the data bus subscriber 20b . The participant exits 22 of the data bus subscriber 20b be connected to actuators who, for example, carry out a specific action with the help of the data addressed to them.

The data bus participants shown in this exemplary embodiment 20a , 20b , 20n are due to their inputs and outputs 21st , 22 that can be connected to sensors or actuators, often referred to as I / O modules. Even if the data bus participants 20a , 20b , 20n In the exemplary embodiment shown here, they are shown as being spatially separate from the sensors or actuators, so the sensors or actuators can also be located in the data bus subscriber 20a , 20b , 20n be integrated.

The different interfaces 9 to 19th on the module units 8a , 8b 8n related to 2nd For example, a receptacle in the form of a socket and the respective connecting elements, such as the connecting lines, can be explained in detail 7 of the ring bus 6 can each have a plug that can be received by the socket. However, other possibilities are known to the person skilled in the art, such as the interfaces 9 to 19th are to be designed so that the respective connecting elements are electrically or optically connected to the interfaces 9 to 19th can be connected. The skilled worker is familiar with screw, twist, click or plug connections with the aid of which an electrical or optical connection can be established. A male connector is usually received by a female counterpart. This recording usually not only establishes the electrical or optical connection, but also ensures that the two parts are mechanically connected and can only be detached from one another with the application of a certain force. It is also known to the person skilled in the art that not all interfaces 9 to 19th must have the same type. So can for example some of the interfaces 9 to 19th be designed as a plug connection, with other of the interfaces 9 to 19th are designed as screw connections.

The different interfaces 9 to 19th on the module units 8a , 8b , 8n , as in 1 exemplary for the module unit 8a is shown, can be in any position and in any order on the housing of the module unit 8a be arranged. Further interfaces, not shown here, can also be provided on the module units 8a , 8b , 8n be attached, by means of which further data between the module units 8a , 8b , 8n and the data bus subscriber arranged thereon 20b , 20n can be exchanged. Furthermore, other interfaces can also be installed on the module units 8a , 8b , 8n be attached to data between the module units 8a , 8b , 8n exchange, such as one for all module units 8a , 8b , 8n looped through status signal.

In the 2nd an embodiment of a module unit without a data bus device arranged thereon with the switching means 23 , 24th shown in the first switching state. In the 2nd shown module unit 8a is the in 1 shown module unit 8a . In the 2nd shown module unit 8a but can also each of the other module units 8a , 8b , ..., 8n out 1 be. As in 1 shown is the module unit 8a with the first input interface 9 with the local bus master 3rd connected and with the first output interface 10th with the modular unit 8b . This direction forms the downward direction for the data in the ring bus 6 , ie the direction from the local bus master 3rd path. The second input interface 11 the module unit 8a is with the modular unit 8b connected and the second output interface 12 is with the local bus master 3rd connected. This direction forms the upward direction for data in the ring bus 6 , so towards the local bus master 3rd there. The data in the downward and upward direction are in the ring bus 6 from one participant - one participant can be a modular unit 8a , 8b , ... 8n with or without a data bus device arranged on it 20a , 20b , ..., 20n be or just a data bus participant 20a , 20b , ..., 20n be - directed to an upstream or downstream participant. As already regarding 1 has to be described so that the ring bus 6 is not interrupted, the data can be passed from one participant to another. The functionality of the ring bus 6 ensure the data must go up and down through the module units 8a , 8b , ..., 8n be looped or forwarded without interruption, even if, for example, no data bus subscriber 20a on the module unit 8a is appropriate. For this, the module unit points 8a a first switching means 23 for the downward direction and a second optional switching means 24th for the upward direction. As in 2nd shown, the first switching means switches 23 the downward direction and the second switching means 24th switches the upward direction. The first switching device switches 23 the downward direction such that in the 2nd shown first switching state the first input interface 9 the module unit 8a electrically or optically conductive with the first output interface 10th connected is. The data starting from the local bus master 3rd are accordingly directly in the downward direction by the module unit 8a to the module unit 8b headed. The second switching means optionally shown here 24th switches the upward direction such that in the 2nd shown first switching state the second input interface 11 the module unit 8a electrically conductive with the second output interface 12 connected is. The data comes from the module unit 8b are accordingly sent directly to the local bus master 3rd forwarded. As an alternative to the second switching means 24th can also be a direct connection between the second input interface 11 and the second output interface 12 to be available.

In the embodiment shown here, the first and second switching means 23 , 24th either electronic switches or electromechanical switches. The person skilled in the art knows that the respective switching means 23 , 24th can be constructed from one or more electronic switches or electromechanical switches. For example, the respective switching means 23 , 24th be built from a relay with several relay contacts, such as several NC and NO contacts. The switching means 23 , 24th can consist of either semiconductor elements or relays and can be controlled by the control input in the form of an electrical control signal. However, it is also known to the person skilled in the art that the first and the second switching means 23 , 24th also mechanical switches - not shown here - which are dependent on a mechanical control input, such as one on the data bus subscriber 20a attached, pin-shaped geometry can switch between the first and the second switching state.

As in 2nd is shown, the module unit 8a a control input interface 19b on, to receive the control input, for example a control signal, from a data bus subscriber 20a and / or for forwarding the control input to the switching means 23 , 24th . In the in 2nd shown example controls the control input all switching means shown 23 , 24th at the same time. That means that all switches in the switching means 23 , 24th depending on the control input switch simultaneously, so that the switching means 23 , 24th depending on the control input, either the defined first switching state or the defined one assume second switching state. The switching means 23 , 24th can also be switched one after the other. In the in 2nd shown embodiment are the switching means 23 , 24th in the first switching state. The switching means can perform this first switching state 23 , 24th assume, for example, if there is no control input, for example if there is no data bus subscriber 20a with the modular unit 8a connected is. As already described above, this becomes the ring bus 6 in the absence of a data bus participant 20a , or in the absence of a control input from the data bus subscriber 20a not interrupted. Ie in the event of an error on the part of the data bus participant 20a For example, the first switching state can be assumed because there is no corresponding control input. This error case can be that the data bus participant 20a is no longer able to process the signals or the data bus device 20a outputs incorrect output or mechanically at least partially from the module unit 8a has solved, so that not all contacts exist.

The switching means 23 , 24th can in the modular unit 8a be integrated, or outside the module unit 8a are located. Furthermore shows 2nd that at least one data connection interface 13b , 15b per switching device 23 , 24th is switched to earth in the first switching state. This enables that in the first switching state at least at the two data connection interfaces 13b , 15b a defined zero signal is present. However, the person skilled in the art knows that the switching means 23 , 24th even without grounding the data connection interfaces 13b , 15b function according to the invention in the first switching state. The data connection interfaces 14b and 16b are in the in 2nd shown embodiment not connected.

2nd also shows that the module unit 8a still a voltage connection interface 17b , 18b for connecting a voltage source to the data bus device 20a having. The voltage connection interface 17b , 18b can be similar to the other interfaces on the module unit 8a be pronounced so that there is a detachable connection of the data bus subscriber 20a with the modular unit 8a is possible. If a data bus participant 20a on the module unit 8a can be arranged, the voltage connection interface 17a , 18a the data bus participant 20a supply with mains voltage so that the data bus device 20a can be operated. The person skilled in the art knows that the respective voltage source is located in the module unit 8a can be located or outside the module unit 8a can be arranged.

3rd shows a schematic circuit diagram of an embodiment of a module unit 8b with a data bus participant attached to it 20b with the switching means 23 , 24th in the second switching state. In the 3rd shown module unit 8b is already in 1 shown module unit 8b with a data bus participant arranged thereon 20b . However, the module unit shown can 8b even those already in 2nd shown module unit 8a with a data bus participant attached to it 20a be, or for example the in 1 shown module unit 8n .

As already regarding 1 The different interfaces can be described 9 to 19th on the module unit 8b be executed differently. In the in 3rd shown embodiment, the interfaces 13b to 19b that the data bus subscriber 20b with the modular unit 8b connect, be designed as plug connections, so that the data bus subscriber 20b simply by hand onto the module unit without the use of tools 8b can be inserted. The data bus participant can do this 20b Have interfaces that match the interfaces 13b to 19b the module unit 8b correspond and that with the interfaces 13b to 19b can be connected.

The advantage of the modular unit 8b is that the data bus subscriber 20b while the bus is in operation on the module unit 8b can be arranged. As already described above, this can be done by the data bus subscriber 20b on the module unit 8b is stuck. After all interfaces 13b to 19b are connected and the data bus subscriber 20b for example via the voltage connection interface 17b , 18b is supplied with voltage, the data bus participant 20b immediate control input in the form of an electrical signal via the control input interface 19b to the module unit 8b submit so that the switching means 23 , 24th switch from the first switching state to the second switching state. The data bus participant 20b can also control input at a later time via the control input interface 19b submit. For example after this has been initialized or an input of the data bus participant 20b how regarding 1 was described, connected, etc.

In the in 3rd In the embodiment shown, the control input is in the form of an electrical signal at the control input interface 19b as long as the data bus participant 20b with the modular unit 8b connected is. As an alternative to this, a suitable electronic circuit can also be used, which switches 23 , 24th enables, between the first and the second switching state depending on short switching pulses, starting from the module unit 18b to switch back and forth.

In the in 3rd The second switching state shown is the first data connection interface 13b with the first input interface 9 connected and the second data connection interface 14b is with the first output interface 10th connected, the third data connection interface 15b is with the second input interface 11 connected and the fourth data connection interface 16b is with the second output interface 12 connected. A direct connection in the module unit 8b between the respective input and output interfaces takes place in the second switching state, as in 3rd shown, not instead. Instead, the upward and downward movement of the ring bus 6 via the data connection interfaces 13b to 16b by the data bus participant 20b looped. The data bus participant 20b can carry out processing with the looped through data in upward and / or downward direction before it is sent to the corresponding output interface 10th or 12 is forwarded.

In the last one in the ring bus 6 arranged module unit 8n can the second switching means 24th also the in 3rd Use the switching state shown to receive data coming from the downward direction through the data bus subscriber 20n to grind and then send again in the upward direction. In this case there is no bridge unit on the last module unit 8n which otherwise requires the first output interface 10th with the second input interface 11 would connect.

The modular unit 8b it also allows the data bus participant 20b can be removed during operation. After the data bus participant 20b again from the module unit 8b was removed and the connection of the data bus participant 20b from the control input interface 19b has been separated, the control input is also removed or the control signal is set to zero. This has the consequence that the switching means 23 , 24th return to the first switching state, as in 2nd is shown and a downward and upward transmission takes place.

Reference symbol list

1

programmable logic controller ( PLC )

2nd

parent bus

3rd

Local bus master

4th

first interface

5a, b

second interface

6

Ring bus

7

Connecting lines

8a, b, n

Modular units

9

first input interface

10th

first output interface

11

second input interface

12

second output interface

13a, b

second data connection interface

14a, b

first data connection interface

15a, b

third data connection interface

16a, b

fourth data connection interface

17a, b, 18a, b

Voltage connection interface

19a, b

Control input interface

20a, b, n

Data bus participants

21st

Participant entrance

22

Participant exit

23

first switching means

24th

second switching means

Claims (14)

A module unit (8a, 8b, 8n) for connecting a data bus subscriber (20a, 20b, ..., 20n) to a local bus (6, 7), comprising: a first input interface (9) and a first output interface (10) connectable to the local bus (6, 7), a first data connection interface (14b) connectable to the data bus subscriber (20a, 20b, ..., 20n), a second data connection interface (13b) connectable to the data bus subscriber (20a, 20b, ..., 20n), and a first switching means (23) which is adapted: as a function of a control input, St, to assume a first or a second switching state from the data bus subscriber (20a, 20b, ..., 20n); in the first switching state to connect the first input interface (9) to the first output interface (10) and to connect the second data connection interface (13b) to a fixed potential; and to connect the first data connection interface (14b) to the first output interface (10) in the second switching state. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the local bus (6, 7) is designed as a ring bus, and wherein the first input interface (9) and the first output interface (10) are adapted to pass data. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the first input interface (9) has at least one detachable electrical contact for connection to the local bus (6, 7) and / or the first output interface (10) has at least one detachable electrical contact Has contact for connection to the local bus (6, 7). The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the first data connection interface (14b) has at least one detachable electrical contact for connection to the data bus subscriber (20a, 20b, ..., 20n) and / or wherein the second Data connection interface (13b) has at least one detachable electrical contact for connection to the data bus subscriber (20a, 20b, ..., 20n). The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the module unit (8a, 8b, 8n) has at least one mechanical connecting element for connection to a further module unit (8a, 8b, 8n), wherein the first output interface (10) of the module unit (8a, 8b, 8n) can be electrically connected to a first input interface (9) of the further module unit (8a, 8b, 8n), or the first input interface (9) of the module unit (8a, 8b, 8n) can be electrically connected to a first output interface (10) of the further module unit (8a, 8b, 8n). The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the module unit (8a, 8b, 8n) has at least one further connecting element for mechanical connection to a data bus subscriber (20a, 20b, ..., 20n), the first data connection interface (14b) and / or the second data connection interface (13b) can be electrically connected to the data bus subscriber (20a, 20b, ..., 20n). The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the module unit (8a, 8b, 8n) further comprises: a second input interface (11) and a second output interface (12) for connecting to the local bus (7), a third and a fourth data connection interface (15b, 16b) for connection to the data bus subscriber (20a, 20b, ..., 20n), and a second switching means (24) which is adapted: depending on the control input, St, from the data bus subscriber (20a, 20b, ..., 20n) to assume a third or a fourth switching state, and in the third switching state to connect the second input interface (11) to the second output interface (12) and in the fourth switching state to connect the third data connection interface (15b) to the second input interface (11) and / or to connect the fourth data connection interface (16b) to the second output interface (12). The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the first switching means (23) is electrically controllable for controlling the first and the second switching state and / or the second switching means (24) is electrically controllable for controlling the third switching state and the fourth switching state. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein if there is no control input, St, the first switching means (23) is adapted to assume the first switching state and / or the second switching means (24) is adapted to the third Switch state. The module unit (8a, 8b, 8n) according to Claim 7 , wherein the second switching means (24) in the third switching state is adapted to connect the third data connection interface (15b) to a fixed potential. The module unit (8a, 8b, 8n) according to any one of the preceding claims, wherein the control input, St, is a binary control signal. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the first switching means (23) and / or the second switching means (24) has a semiconductor switch. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the module unit (8a, 8b, 8n) has a voltage connection interface (17b, 18b) for connecting a voltage source to the data bus subscriber (20a, 20b, 20n). The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the module unit (8a, 8b, 8n) has a control input interface (19b) for receiving the control input, St, from the data bus subscriber (20a, 20b, ..., 20n) and / or for forwarding the control input, St, to the first switching means (23) and / or to the second switching means (24).

Images