Method for assigning addresses to bus participants

Abstract

The invention relates to a method for assigning an address to a bus participant connected to a data bus, wherein the bus participant is electrically and in particular also mechanically coupled to a corresponding substrate, the substrates each comprising an electrical test element; the substrates are electrically connected to adjacent substrates along a row, the substrates forming a test circuit in which the test elements are connected in series; a central unit is connected to the test circuit; a test current is applied to the test circuit; at least one bus participant, in particular a bus participant without a bus address, makes a change to the test circuit; the change to the test circuit is measured by the central unit; and based on the change to the test circuit, the position of the bus participant making the change or the position of the bus participant with the bus address is determined, and the bus address is assigned to the bus participant making the change or to the bus participant without the bus address.

Description

Technical Field

[0001] The invention relates to a method for assigning addresses to bus participants connected to a data bus. Background Art

[0002] Automated industrial processes require a large number of field devices, such as I / O modules, to monitor and control the industrial processes. The I / O modules are in turn controlled, for example, by a programmable logic controller (PLC). In this regard, the PLC can address the different bus participants via their respective bus addresses.

[0003] For this purpose, bus addresses must be assigned to the bus participants during installation, which preferably also reflect the respective physical location of the bus participants. This assignment of bus addresses to bus participants can be quite laborious. Furthermore, it may be necessary to repeat the address assignment immediately after any changes are made to the bus participants. Summary of the Invention

[0004] The basic object of the invention is to simplify the address assignment of bus participants connected to a data bus.

[0005] This object is achieved by the method according to the invention.

[0006] In the method according to the present invention,

[0007] - electrically and in particular also mechanically coupling the bus participants to respective substrates, the substrates each comprising an electrical test element;

[0008] - electrically connecting the substrates to adjacent substrates along a row, the substrates forming a test circuit in which the test elements are preferably at least partially connected in series;

[0009] - Connect the central unit to the test circuit;

[0010] - applying a test current to the test circuit;

[0011] at least one bus participant, in particular a bus participant without a bus address, makes a change to the test circuit;

[0012] - measuring changes in the test circuit by the central unit;

[0013] - Based on the change in the test circuit, determining the position of the bus participant that has changed or the position of the bus participant without a bus address and assigning a bus address to the bus participant that has changed or the bus participant without a bus address.

[0014] The application is based on the idea that by changing the test circuit it is possible, for example, to determine the position of a bus participant without a bus address, in particular in the case of a change by a bus participant without a bus address. Alternatively, it is naturally also possible that (for example, all) bus participants with an address are changed, it is then possible to identify which bus participant has not changed and accordingly does not yet have a bus address.

[0015] In general, the presence of at least one bus participant without a bus address can be identified from the change. Furthermore, the position of the bus participant can be determined, for example, in an automated manner, so that a bus address can then be assigned to the bus participant without a bus address. The assignment of the bus address can thus take place automatically. Furthermore, the bus address corresponding to the identified physical / mechanical position of the bus participant can be assigned in accordance with the physical / mechanical position of the bus participant.

[0016] In this regard, the physical position can in particular be detected by means of test elements in the substrate. The test elements are preferably known to the central unit, so that it is possible to infer from the properties of the test circuit, i.e. from the test current, where the bus participant without a bus address is arranged.

[0017] Further details of the method according to the application will be described below.

[0018] The central unit can in particular be part of, or can be connected with, a programmable logic controller (PLC). The central unit can also be used as a bus coupler, which provides the bus participant as a single or multiple fieldbus device in a fieldbus, for example. In this case, the PLC can then communicate with the central unit acting as a bus coupler via the fieldbus.

[0019] The substrate can in particular be an element arranged adjacent to or adjoining the respective bus participant, and the bus participant can in particular also be mechanically fastened to the element. The substrate can be at least partially plate-like and can preferably be electrically connected to one another along a row. In this regard, the substrates can be connected to one another directly or via electrical lines. For example, each substrate can have two input contacts and two output contacts, wherein a test element can be connected between one input contact and one output contact, while the remaining contacts can be electrically connected directly to one another (return line). After the last substrate, a terminal element can also be provided, which electrically connects the two output contacts of the last substrate. The terminal element can likewise have a test element in the connection. The terminal element can thus terminate the test circuit on one side of a row of substrates, while the central unit terminates or closes the test circuit on the side arranged opposite the terminal element.

[0020] There is preferably exactly one test element and / or exactly one substrate per bus participant. Thus, there is in particular a 1 : 1 relationship between the bus participant and the test element and / or the substrate.

[0021] The central unit is then connected to the test circuit, wherein in particular the central unit applies a test current into the test circuit, for example by applying a fixed voltage.

[0022] During the application of the test current, the bus participant without a bus address can be informed that it is now determined. In turn, the bus participant without a bus address (or, as mentioned above, alternatively, all bus participants with a bus address) can make a change to the test circuit. For example, the test circuit can be short-circuited by the bus participant without a bus address, so that the test circuit is then "short-circuited" and only a few test elements are electrically active in the test circuit. The change at the test circuit can then be measured by the central unit, for example by detecting a changed voltage drop or a changed test current.

[0023] On the basis of this change, it can be determined by the central unit which bus participant or which participants have not yet have a bus address. For example, it can be identified that, in the case of the "short-circuited" test circuit, the bus participant without a bus address must be arranged at the end of this short-circuited test circuit.

[0024] The bus address(es) is / are then assigned to the bus participant(s) identified in this way. The bus address can be, for example, an IP address or an Ethernet address or a CAN identifier.

[0025] Advantageous refinements of the application can be gathered from the description, the figures and the dependent claims.

[0026] According to an embodiment, the change made by the bus participant making the change comprises short-circuiting the test circuit. In this respect, in particular, the short-circuiting takes place in such a way that all substrates (viewed from the central unit) and thus also the test elements arranged behind the bus participant making the change are electrically removed from the test circuit. Due to the short-circuiting, the central unit can therefore only temporarily detect the test elements up to the bus participant making the change, so that the test circuit is changed. Due to the change that can be measured in this way, it is possible to detect the mechanical position of the bus participant making the change closest to the central unit, i.e. in the order of the substrates.

[0027] The change does not necessarily have to be a short circuit of the test circuit. For example, it is also possible to make a change by feeding in a current or a voltage, setting a point of the test circuit to a reference potential, etc. The change can generally have any desired property, as long as it is visible to the central unit of the bus participant in which the change is made, e.g. the first bus participant. In particular, it is also visible to subsequent bus participants that a previous bus participant has made a change.

[0028] According to a further embodiment, the change of the test circuit is made in response to a request message of the central unit, wherein the request message is preferably sent as a broadcast. In response to the request message, the change of the test circuit is further made preferentially by a bus participant that has not yet been assigned a bus address. The request message can preferably be sent via the data bus by broadcast, since a bus participant that has not been assigned a bus address can also receive a broadcast. The broadcast can also be designated as a broadcast message, which is intended to be received and processed by all bus participants. In response to the broadcast, all participants that do not yet have a bus address can make a change to the test circuit.

[0029] If the test circuit comprises, for example, ten substrates, which comprise a corresponding number of test elements, and the test circuit is short-circuited by a bus participant on substrate #3, the central unit can detect, for example, only the first three test elements, i.e. the test elements of substrates #1 to #3. It is then visible to the central unit that the first bus participant without a bus address is seated on substrate #3, which can then be assigned a suitable bus address, as described below.

[0030] Generally, after the request message and the change of the test circuit by one or more bus participants, the position of at least one bus participant that made the change is determined, wherein in particular the position of the first bus participant or the bus participant that made the change closest to the central unit is determined.

[0031] According to a further embodiment, after the position of the bus participant, in particular of the first bus participant that made the change, is determined, a bus address is assigned by an assignment message, which is preferably sent as a broadcast. The assignment message then arrives via the data bus after the bus participant has made the change of the test circuit, and subsequently the bus participant receives the bus address contained in the assignment message.

[0032] According to a further embodiment, in order to detect whether a bus participant closer to the central unit has made a change to the test circuit, a voltage is determined at the test element of the base plate of the respective bus participant, in particular by means of a comparator. If the voltage is zero, i.e. if there is no current at the test element configured as a resistor, for example, the bus participant is not the one closest to the central unit that made the change. In this case, the bus participant does not receive the bus address contained in the distribution message. In this way, it is prevented that multiple bus participants receive the same bus address.

[0033] The comparator preferably digitizes the voltage at the test element, wherein the comparator can be connected to a first GPIO pin (general purpose input output pin) of the bus participant, in particular. The first GPIO pin can also be configured as an input. This greatly simplifies the implementation of the part of the bus participant, since the bus address contained in the distribution message is only received when a high level is applied to the GPIO pin, for example.

[0034] The change of the test circuit can be made by means of a second GPIO pin of the bus participant configured as an output. The base or gate of a transistor can be connected to the second GPIO pin, for example, and connected between an input contact or an output contact of the base plate of the respective bus participant, for example, in order to selectively cause a short circuit between two input contacts or two output contacts. If the transistor is then conductively connected by means of the second GPIO pin, a short circuit is caused, so that a change of the test circuit is present. The test circuit is preferably terminated after the bus participant has received the bus address, so that the other bus participants can then obtain their bus address by the same method steps.

[0035] It can be understood that additional electronic elements can also be coupled into the test circuit by means of a transistor (or also decoupled), so that a change of the test circuit is then present in this way, in particular without a short circuit.

[0036] According to a further embodiment, the transfer of the data bus to the bus participants and the central control also takes place via the base plate. The base plate can thus have transmission means for the data bus, for example two or four further lines for a CAN bus (controller area network bus). The data bus can in particular also be a field bus, for example a CANopen bus. However, other field buses can also be envisaged, for example SERCOS, Ethernet / IP, etc. However, it can be understood that other communication buses can also be used as data buses independently of the protocol used.

[0037] According to a further embodiment, the test elements comprise a respective ohmic resistor and / or a diode. In addition, the test elements of the base plate are preferably each identical.

[0038] The test elements of the substrate can be known to the central unit. Due to the known test elements, the central unit can then determine how many and / or which test elements are currently electrically active in the test circuit in the case of a known applied / induced test current or a known voltage applied to the test circuit. For example, when a circuit is made on the substrate #3 by the bus participant, the central unit will be able to determine a lower voltage at the same applied test current if only three test elements are electrically active in the test circuit than, for example, in the case of ten test elements being electrically active in the test circuit. The mechanical position of the bus participant making the change can in particular be determined from the voltage applied to the test circuit and / or from the current of the test circuit.

[0039] The test elements can also typically be another passive component, for example a coil or a capacitor. In this case, the test current can be, for example, alternating current. The application of the test current is to be understood such that the central unit applies a predetermined voltage to the test circuit or applies a predetermined current into the test circuit. The central unit can measure the voltage and / or the current at / in the test circuit.

[0040] It is also possible that the test elements are active components, for example voltage sources or current sources. In this respect, for example, the central unit can then be caused to measure the cumulative voltage produced by the various voltage sources in the test circuit. In this respect, the voltage will then be higher at a point in time at which more test elements in the test circuit are electrically active.

[0041] Alternatively or additionally, the test elements can also produce a temporal change of the test circuit and / or of the test current, so that, for example, a clocked temporal delay and / or clocking of the test current can occur.

[0042] According to a further embodiment, it can be identified whether there is one or more substrates without a bus participant. This identification can in particular be carried out by the central unit. To this end, a list of all allocated and unallocated addresses can be maintained (for example by the central unit). It can then see from the list of substrates without a bus participant. In particular, all bus participants can briefly in turn make a change to the test circuit (for example in response to a request by the central unit) to keep the list up to date in this way.

[0043] According to an embodiment, the position of at least one substrate without a bus participant can then also be determined from the list. Thereby, the mechanical position of the empty substrate can preferably be known. This can then be displayed, for example, in a planning tool.

[0044] As already mentioned, according to an embodiment, a terminal element can be provided after the last substrate which closes the test circuit. The absence of the terminal unit can preferably be identified by the central unit. In particular, the absence can be identified by a current which is completely interrupted in the test circuit.

[0045] According to another embodiment, the method is repeatedly performed, in particular until all bus participants have been assigned a bus address. At least the following steps are preferably repeatedly performed by the bus participant closest to the central unit that does not have a bus address: changing the test circuit, sending the assignment message and receiving the bus address from the assignment message.

[0046] For the sake of summarizing the procedure, in the following an example will be assumed by way of example, in which there are ten base plates, each of which is connected to a bus participant. For this example, it is assumed that only the bus participants on base plate #3 and base plate #6 do not yet have a bus address. It is further assumed that the central unit applies a constant voltage to the test circuit and that the test elements in all base plates are identical ohmic resistors. In order to assign a bus address to the bus participants on base plate #3 and #6, a request message is sent by the central unit by broadcast to all bus participants, so that the bus participants #3 and #6 each short-circuit the test circuit at their base plate. Since the bus participant #3 is closer to the central unit, all bus participants behind the bus participant #3, and thus also the bus participant #6, become electrically inactive to the test circuit, so that the central unit recognizes that only three resistors in the test circuit, i.e. up to base plate #3, are electrically active. This is reflected in a corresponding change in the current in the test circuit. The central unit can then determine from the current in the test circuit that the bus participant on base plate #3 does not yet have a bus address. The bus address of the bus participant on base plate #3, for example bus address #3, is then transmitted by broadcast to all bus participants by means of an assignment message. The bus participants that already have a bus address then ignore this message. The bus participant #6 also ignores the message, since it recognizes by means of the comparator and the first GPIO pin that the bus participant closer to the central unit should receive the address. The bus participant #3 recognizes via its first GPIO pin, which is at a high level, that it is the bus participant closest to the central unit that does not yet have a bus address, and that it receives the bus address from the assignment message. The bus participant #3 then terminates the short-circuit of the test circuit. Since the bus participant #3 terminates the short-circuit, all test elements up to the bus participant #6 are now electrically active in the test circuit. The current in the test circuit therefore changes again, so that the central unit can now recognize that the bus participant #6 still does not have a bus address. The bus address of the bus participant #6, for example bus address #6, is then again sent by broadcast by means of an assignment message and received by the bus participant #6. After the bus participant #6 has received the bus address, it also terminates the short-circuit of the test circuit. The central unit can then recognize on the basis of the current in the test circuit that all test elements are now electrically active in the test circuit. There are therefore no longer any bus participants without a bus address.

[0047] It is further preferred that the request message is repeatedly and / or cyclically transmitted by the central unit. Thus, newly added devices, for example by hot plugging, can acquire a bus address in an automated manner and thus be able to integrate into the system. Likewise, the central unit can permanently or repeatedly measure the current and / or voltage of the test circuit in order to detect new bus participants. In particular, new bus participants can attract their attention by making a change to the test circuit. The method described herein can then be performed again after the new bus participant has been identified.

[0048] According to a further embodiment, the bus participants are detachably connected to the respective substrate and are electrically coupled to the respective substrate, in particular by means of plug connectors. The bus participants can preferably be clipped on the substrate, wherein the bus participants can preferably be released again from the substrate without tools. When connecting or fastening the bus participants to the respective substrate, the electrical connection between the bus participants and the test circuit and between the bus participants and the data bus can in particular be established automatically.

[0049] According to a further embodiment, the data bus is a field bus and / or at least some of the bus participants are input / output modules (I / O modules). Thus, the bus participants can be field devices.

[0050] A further subject matter of the application is a system comprising a central unit and a plurality of bus participants, each of which is electrically connected and in particular also mechanically coupled to a substrate, the bus participants being connected to a data bus, wherein

[0051] - the substrates each comprise an electrical test element;

[0052] - the substrates are respectively electrically connected to an adjacent substrate along a row, the substrates thereby forming a test circuit in which the test elements are preferably connected in series;

[0053] - the central unit is connected to the test circuit;

[0054] - a test current is applied to the test circuit;

[0055] - at least one bus participant, in particular a bus participant without a bus address, is configured to make a change to the test circuit;

[0056] - the central unit is configured to measure the change to the test circuit;

[0057] - the central unit is configured to determine the location of the bus participant making the change or the location of the bus participant without a bus address based on the change to the test circuit and to assign a bus address to the bus participant making the change or to the bus participant without a bus address.

[0058] The statements made regarding the method according to the application apply correspondingly to the system according to the application. This applies in particular to the advantages and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0059] The application will be described below by way of example only with reference to the accompanying drawings. In the drawings:

[0060] Figure 1 is a system comprising a central unit and a plurality of bus participants attached to a substrate; and

[0061] Figure 2 A flowchart is shown which allocates a bus address to a bus participant. DETAILED DESCRIPTION

[0062] Figure 1 A system 10 is shown which has a central unit 12 and three bus participants 14.1, 14.2 and 14.4.

[0063] The bus participants 14 are fastened to substrates 16, of which five substrates 16.1, 16.2, 16.3, 16.4 and 16.5 are shown by way of example in Figure 1 The central unit 12 and the bus participants 14 are electrically connected to the substrates 16 by plug connectors 18. The substrates 16 are also electrically coupled to one another by plug connectors 18.

[0064] The two plug connectors 18 of the respective substrate 16 which face the central unit 12 serve as input contacts 19a, while the two plug connectors 18 of the respective substrate 16 which are remote from the central unit 12 act as output contacts 19b.

[0065] Each substrate 16 comprises a test element, which is shown here in the form of a test resistor 20. The test resistor 20 is arranged between the two connectors 18 respectively and forms a supply line in a test circuit 22. The test circuit 22 also comprises a termination element 24, wherein the termination element 24 likewise comprises a test resistor 20 which establishes a connection of a return line 26 in the substrate 16.

[0066] The test resistors 20 each have an ohmic resistance of 100 Ω.

[0067] In the central unit 12, a current source 28 is connected into the test circuit 22 and applies a constant test current of 3 mA into the test circuit.

[0068] The central unit 12 also comprises an analog-digital converter (ADC) 30 which detects the voltage currently present at the test circuit 22.

[0069] Each bus participant 14 further comprises a comparator 32, which detects the voltage applied to the substrate 16 or the current in the test circuit 22, respectively. The comparator 32 can be read out via a first GPIO pin 34.

[0070] A second GPIO pin 36 controls a respective transistor 38 of the respective bus participant 14. A short circuit of the test circuit 22 can take place behind the respective test resistor 20 by means of the transistor 38.

[0071] For a better overview, a data bus, for example a CAN bus, via which the central unit 12 and all bus participants 14 communicate with one another, is not shown in the figures.

[0072] Figure 2 The sequence of assigning addresses to the bus participants 14 is now shown. For the following example, it is assumed that only the bus participant 14.1 already has a bus address, while the bus participants 14.2 and 14.4 do not yet have a bus address.

[0073] As long as the bus participants have not yet received a request message from the central unit 12, the second GPIO pin 36 is deactivated in step 100, so that no short circuit of the test circuit 22 takes place. In step 110, the central unit 12 then determines the instantaneous voltage at the test circuit 22 by means of the ADC 30. From this, a conclusion can then be drawn in step 120 about the number of substrates 16. In step 130, the central unit 12 sends a request message as a broadcast via the data bus, which requests the bus participants 14 without a bus address to identify themselves. In response to the request message, the bus participants 14.2 and 14.4 switch the transistor 38 into the conducting state by activating the second GPIO pin 36 in step 140, respectively. A short circuit is thereby created between the output contacts 19b.

[0074] In step 150, the central unit 12 then measures the voltage at the test circuit 22 again. On the basis of the now measured voltage, it is identified in step 160 which one of the bus participants 14 without a bus address is the closest. In the present example, it can be identified that the voltage measured by the ADC 30 indicates that at the point in time only two test resistors 20 are electrically active in the test circuit 22. This results in two substrates currently being "detectable" in step 160. In step 170, the number of detectable substrates is now compared with the number of substrates initially determined. In the present example, if the number is different, the bus address of the bus participant 14.2 is sent in step 180 by means of a broadcast message (allocation message) for the bus participant 14.2. Since the bus participant 14.2 can identify by means of its comparator that it is the bus participant 14 without a bus address closest to the central unit 12, the bus participant 14.2 receives the bus address in step 190 and acknowledges the reception by means of a further broadcast. Alternatively, the reception can also be acknowledged by means of a conventional message, in particular if the address of the central unit 12 is known to the bus participant 14.2. Subsequently, the bus participant 14.2 deactivates its second GPIO pin 36, so that the second bus participant 14.2 terminates the short circuit. Now, the method performs steps 150 to 190 again in order to also allocate its address to the bus participant 14.4.

[0075] By allocating addresses to the bus participants 14.2 and 14.4, the result for the central unit is that the substrate 16.3 is empty and has no bus participant.

[0076] If it is determined in step 170 after the allocation to the bus participant 14.4 that the currently measured number of substrates 16 corresponds to the number of substrates 16 expected in step 120, a transition to step 200 is made, in which a predetermined time is waited for, and then in step 130 a new bus participant without a bus address is sought again. The transition from step 200 to step 130 can in particular enable the hot plug of an additional bus participant 14.

[0077] It can be recognized that by providing test elements, namely test resistors 22, in the substrates 16, the central unit 12 can automatically identify the mechanical position of the bus participants 14. The allocation of addresses to the bus participants 14 can thereby take place in an automated manner, wherein the allocation of the addresses is also directed to the actual physical position of the bus participants 14.

[0078] List of reference signs

[0079] 10 system

[0080] 12 central unit

[0081] 14 bus participant

[0082] 16 substrate

[0083] 18 plug connector

[0084] 19a input contact

[0085] 19b output contact

[0086] 20 test resistor

[0087] 22 test circuit

[0088] 24 termination element

[0089] 26 return line

[0090] 28 current source

[0091] 30 ADC

[0092] 32 comparator

[0093] 34 first GPIO pin

[0094] 36 second GPIO pin

[0095] 38 transistor

[0096] 100 deactivating the second GPIO pin 36

[0097] 110 measuring the voltage via the ADC 30

[0098] 120 determining the number N of substrates 16

[0099] 130 sending a request message

[0100] 140 short-circuiting via the activated second GPIO pin 36

[0101] 150 measuring the voltage at the test circuit 22 via the ADC 30

[0102] 160 determining the number A of substrates which are still electrically active at the test circuit 22

[0103] 170 comparing whether N=A

[0104] 180 sending a bus address via a distribution message

[0105] 190 receiving the bus address, acknowledging and deactivating the second GPIO pin 36

[0106] 200 waiting for a certain time until a newly added bus participant 14 is recognized

Claims

1. A method for assigning addresses to bus participants connected to a data bus, wherein: - electrically coupling the bus participants to respective substrates, the substrates each comprising an electrical test element; - electrically connecting the substrate to its adjacent substrates along the row; - Connect the central unit to the test circuit; - applying a test current to the test circuit; - at least one bus participant makes a change to the test circuit; - measuring changes in the test circuit by the central unit; - Based on the change of the test circuit, determining the position of the bus participant that made the change or the position of the bus participant without a bus address and assigning a bus address to the bus participant that made the change or the bus participant without a bus address.

2. The method according to claim 1, wherein The bus participants are also mechanically coupled to the respective base plates.

3. The method according to claim 1, wherein The substrate forms a test circuit in which the test elements are connected in series.

4. The method according to claim 1, wherein At least one bus participant that makes a change to the test circuit is a bus participant without a bus address.

5. The method according to claim 1, wherein The change made by the bus participant making the change includes short-circuiting the test circuit.

6. The method of claim 1, wherein: The changing of the test circuit is made in response to a request message of the central unit, wherein the changing of the test circuit is made in response to the request message by a bus participant which has not yet been assigned a bus address.

7. The method according to claim 6, wherein: The request message is sent as a broadcast.

8. The method of claim 1, wherein: After the location of the bus participant that made the change has been determined, a bus address is assigned via an assignment message.

9. The method of claim 8, wherein: The allocation message is sent as a broadcast.

10. The method of claim 8, wherein: Whether a bus participant closer to the central unit has made a change to the test circuit is detected by a bus participant without a bus address, wherein the bus address transmitted by the assignment message is received by the bus participant without a bus address closest to the central unit.

11. The method according to claim 10, wherein: In order to detect whether a bus participant that is closer to the central unit has made changes to the test circuit, a voltage is determined at a test element of the substrate of the respective bus participant.

12. The method of claim 11, wherein: The voltage is determined via a comparator at a test element of the substrate of the respective bus participant.

13. The method of claim 1, wherein: The data bus is also transferred to the bus participants and the central control via the base station.

14. The method of claim 1, wherein: The test elements include corresponding ohmic resistors and / or diodes, and the test elements of the substrate are identical.

15. The method of claim 1, wherein: Identify if there are any substrates without bus participants.

16. The method of claim 15, wherein: The position of at least one substrate without a bus participant is determined.

17. The method of claim 1, wherein: A terminal element closing the test circuit is arranged after the last substrate, wherein the absence of the terminal element can be detected by the central unit.

18. The method of claim 1, wherein: The method is repeated until bus addresses have been assigned to all bus participants.

19. The method of claim 1, wherein: The bus participants are removably connected to the respective baseboards and are electrically coupled to the respective baseboards via plug connectors.

20. The method of claim 1, wherein: The data bus is a field bus and / or at least some of the bus participants are input-output modules.

21. A system for assigning bus addresses, comprising a central unit and a plurality of bus participants, each bus participant being electrically coupled to a substrate, said bus participants being connected to a data bus, wherein: - each of the substrates comprises an electrical test element; - the substrates are electrically connected to adjacent substrates along a row, wherein the substrates form a test circuit; - said central unit is connected to said test circuit; - a test current is applied to the test circuit; - at least one bus participant is configured to make changes to the test circuit; - the central unit is configured to measure changes in the test circuit; The central unit is configured to determine, based on the change of the test circuit, the position of the bus participant that made the change or the position of the bus participant without a bus address and to assign a bus address to the bus participant that made the change or the bus participant without a bus address.

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