DE102017012323B3 - Modular unit - Google Patents

Abstract

A module unit (8a, 8b, 8n) for connecting a removable data bus participant (20a, 20b, ..., 20n) ... to a local bus (6, 7) is described. The module unit (8a, 8b, 8n) having 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 control input interface (19b) for receiving an electrical or optical control signal, St, from the data bus subscriber (20a, 20b, ..., 20n), the control signal, St, only after an initialization of the data bus subscriber ( 20a, 20b, ..., 20n) is received, only after a time required for initialization of the data bus subscriber (20a, 20b, ..., 20n), a first only after a time required for initialization of the data bus subscriber (20a, 20b, ..., 20n) required time controllable switching means (23), which is adapted: depending on the control signal, St, from the data bus user (20a, 20b, ..., 20n) to assume a first or a second switching state, and in that first switch ustand to connect the first input interface (9) to the first output interface (10) if no control signal, St, has been received and in the second switching state to connect the first data connection interface (14b) to the first output interface (10) if a control signal, St received.

Description

Field of invention

The present invention relates to a module unit for connecting a data bus user to a local bus, in particular during 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. Several 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 referred to as automation devices.

These automation devices can either be connected directly to a controller of the automation system, or can initially be connected to input and output modules, which are often also referred to as I / O modules. These can then in turn be connected directly to the controller. 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 accomplished with the help of one or more programmable logic controllers, PLCs. The PLCs can be arranged hierarchically or decentrally in an automation system. The PLCs have different performance classes, so that they can take on different control and regulation 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 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 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 the 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 parallel wiring, i.e. One line is laid from each automation device or each I / O module to the higher-level controller, which is very complex. With the increasing degree of automation of an automation system, the cabling effort increases with parallel wiring. This is associated with great effort in the planning, installation, commissioning and maintenance.

This is why bus systems are mostly used in automation technology today, with which the automation devices or the I / O modules can be connected to the controller. In order to further simplify the connection of the individual automation devices or the I / O modules to the bus system, individual groups of automation devices or I / O modules are often first connected to one another using a specialized local bus to form a local bus system and then at least one Participants of this local bus are connected to the bus system that is connected to the controller. The local bus system can differ from the bus system that is used to establish the connection with the controller.
The participant of a group of local bus participants connected to the bus system of the control is often 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 additional logics, circuits or functionalities that are necessary for connection to the bus system of the controller. The local bus master itself can also contain a PLC. This participant can also have logics 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 present in the format of one bus system are converted into the format of the local bus system and vice versa. In most cases, but not necessarily, the local bus master specializes in connecting the local bus to the higher-level bus.

The local buses used are mostly tailored to the specific 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 usually form a subgroup 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). These other data can include information relating to the data, or information relating to internal communication on the local bus. A large number of different pieces of information are known here, which can be added to or in front of the process data according to the bus protocol used. The local bus participants connected to a local bus can also be referred to as data bus participants because they exchange data on the local bus. A data bus subscriber can serve 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 measuring 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 local bus, such as from U.S. 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 passed on in sequence from one data bus subscriber to the other. The data are not sent to all data bus users at the same time, but in sequence, with a data bus user receiving data from its upstream data bus user and forwards data to its downstream data bus user. The data bus subscriber can process the received data between receiving the data and forwarding it. When the data have reached the last data bus subscriber in the series, the data from the last data bus subscriber are returned to the first data bus subscriber one after the other. The return can either be done through all data bus participants or past them with the help of a bypass line. The ring bus thus has a down stream and an 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 participants.
In a closed ring bus arrangement, it is necessary that each slot of the local bus is occupied by a data bus subscriber so that data can be passed on in sequence from one data bus subscriber to the other. If a slot is not occupied by a data bus subscriber, the bus or the downward stream and / or the upward stream is interrupted and forwarding or forwarding of the data no longer works. Removing a correspondingly inserted data bus participant during operation would also immediately interrupt the bus.

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

Summary of the invention

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

The modular 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. Ie the first input interface and a first output interface are adapted to be connected to the local bus. The modular unit according to the invention also has a first data connection interface which can be connected to the data bus subscriber. In other words, the data connection interface is adapted to be connected to the data bus user. Furthermore, the modular unit according to the invention has a first switching means which is adapted to adopt a first or a second switching state as a function of 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 being connected to the second 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 that are present at the first input interface are not sent directly to the first output interface, but rather the data the first output interface are dependent on the first Data connection interface, for example from the data that the data bus subscriber provides at this first data connection interface. For example, the switching means can be adapted to adjust the respective switching states according to whether or not a data bus subscriber is connected to the module unit. In the event that no data bus subscriber is connected to the module unit, the switching means can produce the first switching state, for example, whereas the switching means can produce the second switching state in the event that a data bus participant is connected to the module unit.

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

In a preferred embodiment of the modular unit according to the invention, it has a second data connection interface that can be connected to the data bus participant - that is, it is adapted to be connected to the data bus participant - wherein the first switching means is further adapted to connect the second data connection interface to the first input interface. I.e. the data that are present at the first input interface are passed to a second data connection interface so that they can be passed on to the data bus subscriber, who can use them to carry out processing. 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 upstream or downstream of 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 one after the other. The data sent on the local bus can be transmitted in the form of data packets. The data packets can also be referred to as telegrams. A data packet has, for example, a header, payload and advantageously a checksum.

In a further preferred embodiment of the modular unit according to the invention, the local bus is designed as a ring bus, and the first input interface is adapted to receive data, whereas the first output interface is adapted to send 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. receiving can consist exclusively of a signal being present at the first input interface, but no signal processing taking place. In this case one can speak of passive receiving. In the event that signal processing takes place, for example, one can speak of active receiving. The same applies to the transmission if no signal processing is carried out, i.e. If the signal is simply provided at the first output interface, one can speak of passive transmission, whereas if signal processing is carried out, one can speak of active transmission. The first input interface and the first output interface can both be passive or active, i.e. perform none or signal processing, or one of the two interfaces can be active while the other is passive, i.e. one carries out signal processing, while the other does not carry out signal processing. The person skilled in the art is aware that the term signal processing can mean any processing of a signal, for example encoding, decoding, applying modulation or demodulation, conversion to or from a transmission format to another format, etc. Signal processing for converting wired signals to wireless signals. In a ring bus, the data is sent in the form of data packets that pass through all data bus users. 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 occurs can be transferred 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 consecutive cycle frames are advantageously at an equidistant time interval from one another. The specified 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 can be transmitted as an independent symbol or is advantageously contained in a start data packet (SOC packet).

No, one or more data packets are transmitted within the time range of the cycle frame. Idle data are 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 brings about an uninterrupted signal on the local bus. The signal enables the data bus participants to synchronize themselves with it in terms of time. The cycle frame advantageously also has a trailer. The trailer has a variable length and follows the time range for data transmission, preferably up to the following start identifier (SOC) of the next cycle frame. The trailer advantageously has idle data.

The data packets transmitted in the cycle frame are preferably generated originally by the local bus master and sent to the data bus participants via the ring bus. When generating, the local bus master can insert process data received from the controller, e.g. a PLC, 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 pass through the individual data bus participants of the ring bus step by step. The data packet can have a large number of symbols, each symbol having a specific number of bits, for example 8 bits that is 1 byte. The data packet accordingly passes through the data bus participants in units, pieces or parts, for example in the form of symbols. The data bus subscribers accordingly only have part of the data packet available at any given time. When we talk about data here, it can also mean a symbol of the data packet that is currently passing through the ring bus. A data package that carries process data can also be referred to as a process data package. The process data packet has the process data that are sent and / or received by the data bus users of the local bus. The process data packet advantageously does not have an address for the transmission of the process data to or from a data bus user in the local bus. In the process data package, the process data are arranged in such a way that data bus users can recognize the process data belonging to the respective data bus user based on the respective position of the process data in the process data package, for example one or more bits within an assigned coherent data block (1 byte). The process data packet advantageously has an identifier (IDE) that is assigned to the type of data packet, that is to say the process data packet, and can be identified by the data bus subscriber.

A data packet can, however, 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 participant. The communication data packet advantageously has an address which is assigned to at least one data bus user. 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 modular unit according to the invention, the first input interface has at least one releasable electrical contact for connection to the local bus and / or the first output interface has at least one releasable electrical contact for connection to the local bus. Signals from the upstream data bus subscriber or the upstream module unit can be received via the one electrical contact of the first input interface and signals can be sent to the downstream data bus subscriber or the downstream module unit via the one electrical contact of the first output interface. Sending and receiving can be passive or active. The person skilled in the art is also aware that the interfaces can also have a different number of contacts and that the number only depends 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 enter into a fixed connection, but can be detached from each other by exerting a certain force.

In a further preferred embodiment of the modular unit according to the invention has the first data connection interface and / or the second data connection interface each have at least one releasable electrical contact for connection to the data bus subscriber. The second data connection interface can be adapted to send signals to the data bus participant via the contact, this sending being passive or active, and the first data connection interface being adapted to receiving signals from the data bus participant, this receiving being passive and active. The person skilled in the art is also aware that the interfaces can also have a different number of contacts and that the number only depends on the specific design of the data bus users. 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 modular unit according to the invention, it has at least one connecting element to be connected to a further modular unit, the first output interface of the modular unit being electrically connected to a first input interface of the further modular unit, or the first input interface of the modular 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 only being able to be released again 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 locking hooks on one side and recesses or undercuts on the opposite side, so that when two module units are arranged next to each other, the locking hooks of one module unit into the recesses or the undercuts of the other module unit grip so that these can be mechanically but detachably connected. However, the person skilled in the art is also aware of other possibilities of how two modular units can be mechanically connected to one another in a detachable manner and which geometries have to be arranged on the modular units for this purpose. When connecting the module units, the connecting element is designed in such a way that an electrical connection of the interfaces also takes place when the module units are connected. The first output interface of the one module unit is electrically connected to the first input interface of the other downstream module unit. The connecting element then ensures that the modular units can only be detached from one another again by applying a certain force that exceeds the holding force of the connecting element, and thus the electrical connections are detached again. The module units can also be adapted so 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 another module unit with its connecting element is directly attached to the one already fixed on the top-hat rail Module unit can be fixed. This allows several modular units to be lined up and fixed to the top-hat rail. 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 modular unit according to the invention, it has at least one connection element 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 be designed at least in such a way that it allows a releasable mechanical connection of the data bus subscriber to the module unit. For example, this can be implemented by means of suitable plug-in or clamping connection elements on the module unit and on the data bus user so that the data bus user can only be released from the module unit again when a holding force provided by these elements is applied. It is also conceivable that safety elements are used which prevent the data bus subscribers from being accidentally released, for example in the event of strong vibrations. These securing elements can, for example, only be released with a tool or represent an additional holding force. If the data bus participant is connected to the module unit, then the first and / or second data connection interface are also connected to the data bus participant, which has corresponding complementary contacts. This can be done with the appropriate plug or clamp contacts.

In a further preferred embodiment of the modular 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 to be sent from a downstream data bus subscriber or a downstream module unit to 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 passive or active. 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 refinement, the data is 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 the 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 other words, in this refinement, 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 subscribers 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 modular 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 the first and / or second control means assume a corresponding switching state in accordance with the electrical signal. The phrase “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 one first switching means, it is designed in this way. If the module unit has a plurality of switching means, at least one switching means is designed in this way, but preferably all switching means are designed in this way. The same control signal can be applied to both switching means, so that both switching means are controlled at the same time, or the switching means can have different control signals applied to them. The control signal can for example be generated by the data bus subscriber itself and only 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 transmission of signals in the downward and upward direction. When the data bus subscriber is connected to the module unit, it can immediately provide a control signal, for example, which causes the switching means to change to the second switching state, so that the signals are no longer routed past the data bus subscriber, but can be processed by it. However, it can also be that the data bus subscriber initially needs a certain 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 is ready or the processing is ready, the data are sent to the data bus participant. The control signal itself can be any signal that is able to transport 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, for example, a binary signal which only indicates whether or not a switching state should 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, such as, for example, a field effect transistor, bipolar transistor or a diode circuit. The electronic switch can be switched by means of the electrical control signal. Electronic switches advantageously have a shorter switching duration than electromechanical switches and are also bounce-free and wear-free. The electronic switch can also be located in or on the module unit.

In a further preferred embodiment of the modular unit according to the invention, the first and / or second switching means are mechanically controllable. That is to say, the control input is a mechanical input and, in accordance with the input, the first and / or second control means assume a corresponding switching state. This means that the switching means are mechanically transferred from the first to the second switching state. For example, this can be done by a geometry arranged on the data bus participant which, when the data bus participant 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 return again be transferred from the second switching state to the first switching state. For this purpose, the geometry can be designed in the shape of a pin, for example, in order to change the switching state in a correspondingly configured switching means.

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

In a further preferred embodiment of the modular 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 participant is connected to the module unit, there is no control signal or there is no geometry that causes a switching state. In this case, the first switching state is preferred, which allows the signals to be passed through on the local bus in the downward and upward direction. In this case, the module unit provides a feed-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 modular unit according to the invention, the first switching means and / or the second switching means are adapted in the first switching state 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 modular unit according to the invention, it can have a housing made of plastic or another non-conductive material, so that the interfaces are electrically isolated from the environment. The housing can, for example, be adapted to accommodate the data bus subscriber in a supporting manner. Furthermore, the housing can be adapted to fix the module unit on a top hat rail.

In a further preferred embodiment of the modular unit according to the invention, the modular unit has a voltage connection interface for connecting a voltage source to the data bus user. 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 it can be arranged outside the module unit.

In yet another preferred embodiment of the modular unit according to the invention, the modular unit has a control input interface for receiving the control input from the data bus user. The control input interface can also be designed similarly to the data connection interfaces and the voltage connection interface, so that it enables the data bus subscriber to be releasably connected 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 emerge 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 modular unit according to the invention, and an exemplary ring bus;
• 2 a schematic circuit diagram of an embodiment of the modular unit according to the invention without a data bus subscriber arranged thereon with the switching means in the first switching state; and
• 3 a schematic circuit diagram of an embodiment of the modular unit according to the invention with a data bus participant arranged thereon with the switching means in the second switching state.

Description of preferred exemplary 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 exemplary and that all of the elements, modules, components, participants and units belonging to the automation system can be configured differently, but can still fulfill the basic functionalities described here.

In the 1 The automation system shown has a higher-level controller 1 on the for example with a programmable logic controller, PLC, can be implemented. Such a PLC 1 basically serves to control and regulate the process carried out by the automation system. Nowadays, PLCs are taking over 1 In automation systems, however, there are also more extensive functions, such as visualization, alarming and recording of all data relating to the process, and the PLC acts as such 1 as a man-machine interface. There are PLCs 1 in different performance classes that 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 mostly has a modular structure and consists of individual components that each perform a different task. Usually there is a PLC 1 from a central processing unit (with one or more main processors and memory modules) and several assemblies with inputs and outputs. Such a 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 assemblies in the PLC 1 must be integrated. In today's automation systems, the PLC is 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 the PLC 1 is part of a network via which or from which the PLC 1 Can receive information, instructions, programming, etc. For example, the PLC 1 Via a connection to a computer located in the intranet or the Internet, information about the materials supplied to the process can be obtained, so that the process can be optimally controlled by knowing their number or nature, for example. 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 access the PLC with the help of a computer, also known as a master computer 1 access and check, change or correct their user programming. Access to the PLC is accordingly 1 possible from one or more remote control rooms or control centers. The master computers can optionally have visualization devices for displaying process sequences.

The PLC is used to control the process of the automation system 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 higher-level bus 2 , which in the embodiment shown here can be a field bus, with a local bus master 3 connected to a subordinate local bus system. To the higher-level bus 2 can not only be a local bus master as in the embodiment shown here 3 of a local bus, but also any other participants - not shown here - that are required to communicate with the PLC 1 are designed.

The higher-level bus 2 is in the embodiment shown here with the local bus master 3 connected. The local bus master instructs 3 a first interface 4th on, which is designed in such a way that it connects to the higher-level bus 2 can be connected. the interface 4th can for this purpose have a receptacle in the form of a socket and the higher-level bus 2 may 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, that is, each wire of the higher-level bus 2 is connected electrically or optically with a connection in the modular jack. However, the person skilled in the art is also familiar with other possibilities, such as an interface 4th is to be designed so that the local bus master 3 electrically or optically with the higher-level bus 2 can be connected. Those skilled in the art are familiar with screw, twist, click or plug connections with the help of which an electrical or optical connection can be established. In most cases, a male connector is received by a female counterpart. This receptacle 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 again with the application of a certain force. But it is also conceivable that the higher-level bus 2 firmly with the interface 4th is wired.

The local bus master 3 in the exemplary embodiment shown here has a further second interface 5a , 5b to the local bus master 3 to be connected to the local bus. the local bus in the embodiment shown here as a ring bus 6th 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 6th here and the second part 5b the second interface provides the uplink in the ring bus 6th here.

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

A data packet sent by the local bus master 3 on the local bus 6th is sent through all module units 8a , 8b , ..., 8n and data bus participants connected to them 20a , 20b , ..., 20n . A data bus participant receives it 20a , 20b , ..., 20n from its upstream data bus participant 20a , 20b , ..., 20n or a module unit 8a , 8b , ..., 8n always only part of the data package. After a period of time in which the data contained in this part is received from the data bus participant 20a , 20b , ..., 20n can be processed, the part is sent to the downstream data bus subscriber 20a , 20b , ..., 20n forwarded and at the same time is from the upstream data bus participant 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 pass sequentially through all data bus users 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 a ring bus 6th are designated. The local bus can alternatively also be designed in the form of a strand or a star or a combination or mixed form of the aforementioned. The modular units 8a , 8b , ..., 8n can also be used as the basic elements of the ring bus 6th are designated. The ring bus infrastructure is created by the modular units 8a , 8b , ..., 8n and the data bus participants 20a , 20b , ..., 20n are interchangeable so that the ring bus 6th 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 is removed, the communication between the remaining data bus participants 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 get data from one on the ring bus 6th upstream or preceding participant, for example an upstream module unit, a data bus participant or a local bus master 3 to recieve. Receiving 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 3 . Furthermore, the modular units 8a , 8b , ..., 8n in the exemplary embodiment shown here, each has a first output interface 10 to forward data to a downstream or subsequent module unit and / or data bus participant. In the case of modular unit 8a , sends this data to the downstream module unit 8b with the attached data bus device 20b via the first output interface 10 . Sending can be active or passive, ie signal processing can take place or not. The first input interface 9 and the first output interface 10 serve to propagate data in the downward direction of the ring bus 6th , ie from the local bus master 3 path. Furthermore, the modular units 8a , 8b , ..., 8n also a second input interface 11 and a second output interface 12 on propagating data in the upstream direction of the loop 6th serve, ie to the local bus master 3 down. 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 3 to forward. It can thus be said that the output interfaces 10 and 12 Sender interfaces are, whereas the input interfaces 9 and 11 Receiver interfaces are.

Even if the local bus master 3 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 3 also decentralized from the module unit 8a , 8b , ..., 8n , be arranged. As a person skilled in the art knows, the modular unit 8a , 8b , ..., 8n and the local bus master 3 - which is also a data bus subscriber of the ring bus 6th - can also be connected directly to one another. 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 access to such an electrical or optical connection between the module units 8a , 8b , ..., 8n so that data can be sent in the downlink and uplink direction. For example, the modular units 8a , 8b , ..., 8n have receptacles on the side facing away from the master and contacts on the side facing the master. Will the modular units 8a , 8b , ..., 8n then lined up accordingly, the contacts of one module unit engage 8a , 8b , ..., 8n in the receptacles of the other module unit 8a , 8b , ..., 8n and an electrical or optical connection can be established. The local bus master 3 then has corresponding receptacles on the side, in the contacts of the first module unit 8a grab to so between the interfaces 5a and 9 or the interfaces 5b and 12 to create an electrical or optical connection. However, the person skilled in the art is also familiar with other possibilities, for example pressure contacts, knife and fork contacts, such as two module units arranged directly next to one another 8a , 8b , ..., 8n be able to establish an electrical or optical connection. Also can 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 permanently interconnected inside the housing, for example by means of conductor tracks.

In the case that the modular units 8a , 8b , ..., 8n and the local bus master 3 are to be connected directly to one another, these can also have mechanical receptacles or mechanical connecting elements with which the individual modular units 8a , 8b , ..., 8n and the local bus master 3 can be connected to each other. Here, for example, a module unit 8a , 8b , ..., 8n have a projection on one side and have an undercut on the other side. Will the modular units 8a , 8b , ..., 8n then lined up, a projection engages in an undercut of the other module unit 8a , 8b , ..., 8n so that a mechanical coupling is created. For easy lining up of 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 fastening means. Alternatively or additionally, the modular units 8a , 8b , ..., 8n also have, for example, detachably connectable fastening means with which the modular units 8a , 8b , ..., 8n can either be attached to the DIN rail or to another mount. For this purpose, the detachably connectable fastening means can be exchangeable and a corresponding fastening means for the desired receptacle can be used with the modular units 8a , 8b , ..., 8n connected so that they can be attached to the desired recording.

The ones 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 , 10 , 11 , 12 connected. The data bus participants 20a , 20b , 20n have, for example, an arithmetic-logic unit or another type of calculation kernel with which data can be processed. This processing unit can be a processor, a microcontroller or a computing circuit, which can in particular be formed from gate elements of an integrated circuit. The computing circuit can be designed as digital logic, which is designed in particular 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 6th to process and output data. The data to be processed can either be received from an upstream data bus participant 20a , 20b , 20n , the local bus master 3 or from participant entrances 21st of the data bus participant 20a , 20b , 20n . The participant entrances 21st of the data bus participant 20b can be connected to sensors that send measurement data, status data, etc. Processed data can either be output to a downstream data bus participant 20n or at the participant exits 22nd of the data bus participant 20b . The participant exits can 22nd of the data bus participant 20b be connected to actuators that, for example, use the data sent to them to perform a specific action.

The data bus participants shown in this exemplary embodiment 20a , 20b , 20n are based on their inputs and outputs 21st , 22nd that can be connected to sensors or actuators, also often referred to as I / O modules. Even if the data bus participants 20a , 20b , 20n in the exemplary embodiment shown here as being spatially separated from the sensors or actuators, the sensors or actuators can also be in the data bus user 20a , 20b , 20n be integrated.

The different interfaces 9 to 19th on the module units 8a , 8b 8n which are related to 2 can be explained in detail, for example, have a receptacle in the form of a socket and the respective connecting elements, such as the connecting lines 7th of the ring bus 6th can each have a plug that can be received by the socket. However, the person skilled in the art is also familiar with other possibilities, such as the interfaces 9 to 19th are to be designed so that the respective connecting elements electrically or optically with the interfaces 9 to 19th can be connected. The person skilled in the art is familiar with screw, twist, click or plug connections with the help of which an electrical or optical connection can be established. In most cases, a male connector is received by a female counterpart. This receptacle 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 again with the application of a certain force. The person skilled in the art is also aware that not all interfaces 9 to 19th must be of the same type. So can for example some of the interfaces 9 to 19th be designed as a plug connection, with other 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 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 connected to 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, further interfaces can also be used on the module units 8a , 8b , 8n be attached to data between the modular units 8a , 8b , 8n exchange, such as one through all module units 8a , 8b , 8n looped through status signal.

In the 2 is an embodiment of a modular unit without a data bus device arranged thereon with the switching means 23 , 24 shown in the first switching state. In the 2 module unit shown 8a is the in 1 module unit shown 8a . In the 2 module unit shown 8a but can also be any of the other module units 8a , 8b , ..., 8n out 1 be. As in 1 shown is the modular unit 8a with the first input interface 9 with the local bus master 3 connected and with the first output interface 10 with the module unit 8b . This direction forms the downward direction for the data in the ring bus 6th , i.e. the direction from the local bus master 3 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 3 connected. This direction forms the upward direction for data in the ring bus 6th , i.e. in the direction of the local bus master 3 down. The data in the downward and upward direction are in the ring bus 6th from one participant - one participant can be a module 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 been described, so that the ring bus 6th is not interrupted, the data can be passed from one participant to the other. About the functionality of the ring bus 6th ensure that the data in the uplink direction and in the downlink direction must then also pass through the module units 8a , 8b , ..., 8n be looped or forwarded without interruption, even if, for example, there is no data bus participant 20a on the module unit 8a is appropriate. The module unit 8a a first switching means 23 for the downward direction and a second optional switching means 24 for the upward direction. As in 2 shown, the first switching means switches 23 the downward direction and the second switching means 24 switches the upward direction. The first switching means switches 23 the downward direction such that in the in 2 The first switching state shown is the first input interface 9 the module unit 8a electrically or optically conductive with the first output interface 10 connected is. The data originating from the local bus master 3 are accordingly directly in the downward direction through the module unit 8a to the module unit 8b directed. The second switching means optionally shown here 24 switches the upward direction so that in the in 2 the first switching state shown is 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 3 forwarded. As an alternative to the second switching means 24 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 are switching means 23 , 24 either electronic switches or electromechanical switches. The person skilled in the art is aware that the respective switching means 23 , 24 can be constructed from one or more electronic switches or electromechanical switches. For example, the respective switching means 23 , 24 be constructed from a relay with several relay contacts, such as several break and make contacts. The switching means 23 , 24 can either consist of semiconductor elements or relays and can be controlled by the control input in the form of an electrical control signal. However, the person skilled in the art is also aware that the first and second switching means 23 , 24 also mechanical switches - not shown here - can be 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 2 is shown, has the modular unit 8a a control input interface 19b to receive the control input, for example a control signal, from a data bus participant 20a and / or for forwarding the control input to the switching means 23 , 24 . In the in 2 In the example shown, the control input controls all the switching means shown 23 , 24 at the same time. That means that all switches in the switching means 23 , 24 switch simultaneously depending on the control input, so that the switching means 23 , 24 Depending on the control input, either the defined first switching state or the defined one adopt second switching state. The switching means 23 , 24 but can also be switched one after the other. In the in 2 embodiment shown are the switching means 23 , 24 in the first switching state. The switching means can perform this first switching state 23 , 24 for example accept when there is no control input, for example when no data bus participant 20a with the module unit 8a connected is. As already described above, this creates the ring bus 6th in the absence of a data bus participant 20a , or in the absence of a control input from the data bus participant 20a not interrupted. Ie in the event of an error in 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 or the data bus participant is no longer able to process the signals 20a no longer provides correct output or is mechanically at least partially different from the module unit 8a resolved so that not all contacts exist.

The switching means 23 , 24 can in the module unit 8a be integrated, or outside the module unit 8a are located. Furthermore shows 2 that at least one data link interface 13b , 15b per switching device 23 , 24 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, it is known to the person skilled in the art that the switching means 23 , 24 even without earthing 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 2 shown embodiment not wired.

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

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

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

The advantage of the modular unit 8b is that the data bus participant 20b while the bus is running on the module unit 8b can be arranged. As already described above, this can be done by the data bus participant 20b on the module unit 8b is plugged. After all interfaces 13b to 19b are connected and the data bus participant 20b for example via the voltage connection interface 17b , 18b is supplied with voltage, the data bus participant 20b Immediately a control input in the form of an electrical signal via the control input interface 19b to the module unit 8b release so that the switching means 23 , 24 switch from the first switching state to the second switching state. The data bus participant 20b but can also send the control input at a later point in 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 described, wired, etc.

In the in 3 The embodiment shown is the control input in the form of an electrical signal at the control input interface 19b as long as the data bus participant 20b with the module unit 8b connected is. As an alternative to this, a suitable electronic circuit can also be used to provide the switches 23 , 24 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 3 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 10 connected, the third data link 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 FIG 3 shown not held. Instead, the upward and downward processing of the loop is used 6th 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 uplink and / or downlink processing before it is sent to the corresponding output interface 10 or 12 is forwarded.

In the last in the ring bus 6th arranged module unit 8n can the second switching means 24 also the in 3 Use the switching status shown to transfer data coming from the downward direction through the data bus participant 20n to loop and then to send again in the upward direction. In this case, there is no bridge unit on the last module unit 8n otherwise the first output interface 10 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 has been 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 , 24 resume the first switching state as shown in 2 is shown and a conduction takes place in the downward as well as upward direction.

List of reference symbols

1

programmable logic controller (PLC)

2

higher-level bus

3

Local bus master

4th

first interface

5a, b

second interface

6th

Ring bus

7th

Connecting lines

8a, b, n

Modular units

9

first input interface

10

first output interface

11

second input interface

12

second output interface

13a, b

second data link interface

14a, b

first data link interface

15a, b

third data link interface

16a, b

fourth data link interface

17a, b, 18a, b

Voltage connection interface

19a, b

Control input interface

20a, b, n

Data bus participants

21st

Participant entrance

22nd

Participant exit

23

first switching means

24

second switching means

Claims (12)

A module unit (8a, 8b, 8n) for connecting a removable data bus participant (20a, 20b, ..., 20n) to a local bus (6, 7), comprising: a first input interface (9) and a first output interface (10) can be connected with the local bus (6, 7), a first data connection interface (14b) connectable to the data bus subscriber (20a, 20b, ..., 20n), a control input interface (19b) for receiving an electrical or optical control signal, St, from the data bus subscriber ( 20a, 20b, ..., 20n), the control signal, St, being received only after a time required for initialization of the data bus participant (20a, 20b, ..., 20n) when the data bus participant (20a, 20b,. .., 20n) is ready for processing, and a first electrically or optically controllable switching means (23) which is adapted: depending on the control signal, St, from the data bus participant (20a, 20b, ..., 20n) a first or a to assume the second switching state, and in the first Schaltz State the first input interface (9) with the first output interface (10) to connect if no control signal, St, has yet been received and in the second switching state to connect the first data connection interface (14b) to the first output interface (10) when a control signal, St, has been received. The module unit (8a, 8b, 8n) according to Claim 1 , further comprising: a second data connection interface (13b) connectable to the data bus subscriber (20a, 20b, ..., 20n), the first switching means (23) being adapted to connect the second data connection interface (13b) to the first input interface (9) connect. 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 for passing data through. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the first input interface (9) has at least one releasable electrical contact for connection to the local bus (6, 7) and / or the first output interface (10) has at least one releasable 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 releasable 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 releasable 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 participant (20a, 20b, ..., 20n), wherein the The first data connection interface (14b) and / or the second data connection interface (13b) can be electrically connected to the data bus user (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 connecting to the data bus participant (20a, 20b, ..., 20n), and a second electrically or optically controllable switching means (24) which is adapted: to assume a third or fourth switching state as a function of the control signal St from the data bus subscriber (20a, 20b, ..., 20n), and in the third switching state to connect the second input interface (11) to the second output interface (12) if no control signal, St, has yet been received 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) when a control signal, St, was received. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the first switching means (23) is adapted in the first switching state to connect the second data connection interface (13b) to a fixed potential and / or the second switching means (24) is adapted in the third switching state to connect the third data connection interface (15b) to a fixed potential. The module unit (8a, 8b, 8n) according to one of the preceding claims, wherein the control signal, 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 participant (20a, 20b, 20n).

Images