Determine the sequence of bus nodes in a multipoint communication bus

Abstract

According to one aspect, a method for determining a bus node sequence (102, 104, 106) in a multi-drop communication bus is provided. The method includes, for each bus node (102, 104, 106): sending (200) a request to the bus node (102, 104, 106) using a bus node physical identifier to set the bus node (102, 104, 106) to a loopback mode; transmitting (202) at least one signal to the bus node via a multi-drop communication bus (108); receiving (204) a loopback signal caused by the at least one signal from the bus node (102, 104, 106); and measuring (206) a round trip delay between the at least one signal and the loopback response signal. The method further includes resolving (208) the physical order of the bus nodes (102, 104, 106) in the multi-drop communication bus (108) based on the round trip delay.

Description

Technical Field

[0001] The present invention relates to the field of communication systems and more particularly to determining a bus node sequence in a multi-drop communication bus. Background Art

[0002] When setting up a communication network, such as one that utilizes multi-drop networks, it needs to be configured in order for it to work properly. These networks often require some external means and / or information in order to be configured correctly. For example, multiple network nodes of the same type will require setup / configuration at manufacturing time and / or hardware elements (such as patch cords, rotary switches, etc.) to be able to identify their roles / tasks in the network. If this needs to be performed manually, this will make configuring a network that includes multiple network nodes difficult, laborious, and slow. Furthermore, even if the configuration of the network nodes can be established automatically, it is not known how the network nodes are positioned in the network.

[0003] Therefore, it would be beneficial if there were a solution that could mitigate at least one of these drawbacks. Summary of the invention

[0004] According to a first aspect, a method for determining a sequence of bus nodes in a multi-point communication bus is provided. The method includes, for each bus node, sending a request to the bus node using a bus node physical identifier to set the bus node to a loopback mode, transmitting at least one signal to the bus node via the multi-point communication bus, receiving a loopback response signal caused by the at least one signal from the bus node, and measuring a round trip delay between the at least one signal and the loopback response signal. The method also includes solving a physical order of the bus nodes in the multi-point communication bus based on the round trip delay. The multi-point communication bus includes a multi-point Ethernet bus.

[0005] In an implementation form of the first aspect, the bus node includes a constant delay loopback circuit. This refers to a circuit with a very low jitter or variation of predictable delay, so that the distance between the bus node and the measurement node can be determined in a reliable manner for each bus node based on the round trip delay. The delay itself is not a problem, as long as the delay is known.

[0006] In an implementation form of the first aspect, the constant delay loopback circuit includes an echo canceller and a repeater. The echo canceller can be used to prevent reflection of a signal from a bus node.

[0007] In an implementation form of the first aspect, the at least one signal may be a single pulse or a pulse pattern. The pulse pattern may include a fault detection signal or code and / or may be encoded or modulated to improve reliability of signal transmission.

[0008] In an implementation form of the first aspect, the at least one signal may be an analog signal, and the measuring node and the bus node may have a conversion interface for analog / digital signal conversion.

[0009] In an implementation form of the first aspect, the request includes timing information related to the loopback mode, and the timing information indicates a duration of the loopback mode.

[0010] In an implementation form of the first aspect, the method further includes resolving the physical identifier of the bus node in the following manner: applying a physical identifier allocation strategy, wherein a segment coordinator uses an exclusive physical identifier, and wherein the bus node will use a special physical identifier to detect usage status, which special physical identifier is associated with a transmission opportunity; through the segment coordinator, all bus nodes are set to a response state, commanding them to respond to subsequent search request messages; through the segment coordinator, using at least one search request message to resolve the media access control address of the bus node; based on the media access control address of the bus node, querying the physical identifier of the bus node through the segment coordinator; through the segment coordinator, assigning a unique physical identifier to each bus node.

[0011] According to a second aspect, there is provided an apparatus configured to perform the method of the first aspect.

[0012] In an implementation form of the second aspect, the device comprises an integrated circuit configured to perform the method of the first aspect.

[0013] In an implementation form of the second aspect, the device comprises an elevator system node configured to perform the method of the first aspect.

[0014] According to a third aspect, there is provided an elevator system node configured to perform the method of the first aspect.

[0015] According to a fourth aspect, a method for resolving a physical identifier of a bus node is provided, the method comprising applying a physical identifier allocation strategy, wherein a segment coordinator uses an exclusive physical identifier, and wherein the bus node will use a special physical identifier to detect a usage status, the special physical identifier being associated with a transmission opportunity; through the segment coordinator, all bus nodes are set to a response state, commanding them to respond to subsequent search request messages; through the segment coordinator, at least one search request message is used to resolve the media access control address of the bus node; based on the media access control address of the bus node, the physical identifier of the bus node is queried through the segment coordinator; and through the segment coordinator, a unique physical identifier is allocated to each bus node.

[0016] According to a fifth aspect, there is provided an integrated circuit configured to perform the method of the fifth aspect.

[0017] According to a sixth aspect, there is provided an apparatus configured to perform the method of the fifth aspect.

[0018] According to a seventh aspect, there is provided an elevator system node configured to perform the method of the fifth aspect.

[0019] According to an eighth aspect, there is provided a communication system comprising a multi-point communication bus, at least one bus node communicatively connected to the multi-point communication bus, and the apparatus of the seventh aspect communicatively connected to the multi-point communication bus.

[0020] In an implementation form of the eighth aspect, the communication system includes an elevator communication system.

[0021] According to a ninth aspect, there is provided an apparatus for determining a sequence of bus nodes in a multi-point communication bus. The apparatus includes means for sending a request for each bus node to set the bus node to a loopback mode using a bus node physical identifier, means for transmitting at least one signal to the bus node via the multi-point communication bus, means for receiving a loopback response signal caused by the at least one signal from the bus node, and means for measuring a round trip delay between the at least one signal and the loopback response signal. The apparatus also includes means for resolving a physical order of bus nodes in the multi-point communication bus based on the round trip delay. The multi-point communication bus includes a multi-point Ethernet bus.

[0022] In an implementation form of the ninth aspect, the bus node includes a constant delay loopback circuit. This refers to a circuit with a predictable delay with very low jitter or variation, so that the distance between the bus node and the measurement node can be determined in a reliable manner for each bus node based on the round-trip delay. The delay itself is not a problem, as long as the delay is known.

[0023] In an implementation form of the ninth aspect, the constant delay loopback circuit includes an echo canceller and a repeater. The echo canceller can be used to prevent reflection of a signal from a bus node.

[0024] In an implementation form of the ninth aspect, the at least one signal may be a single pulse or a pulse pattern. The pulse pattern may include a fault detection signal or code and / or may be encoded or modulated to improve reliability of signal transmission.

[0025] In an implementation form of the ninth aspect, the at least one signal may be an analog signal, and the measuring node and the bus node may have a conversion interface for analog / digital signal conversion.

[0026] In an implementation form of the ninth aspect, the request includes timing information related to the loopback mode, and the timing information indicates the duration of the loopback mode.

[0027] In an implementation form of the ninth aspect, the device also includes a device for resolving the physical identifier of the bus node in the following manner: applying a physical identifier allocation strategy, wherein the segment coordinator uses an exclusive physical identifier, and wherein the bus node will use a special physical identifier to detect usage status, which special physical identifier is associated with a transmission opportunity; through the segment coordinator, all bus nodes are set to a response state, commanding them to respond to subsequent search request messages; through the segment coordinator, using at least one search request message to resolve the media access control address of the bus node; based on the media access control address of the bus node, querying the physical identifier of the bus node through the segment coordinator; through the segment coordinator, assigning a unique physical identifier to each bus node. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are intended to provide a further understanding of the present invention and constitute a part of this specification. The accompanying drawings illustrate embodiments of the present invention and together with the description help explain the principles of the present invention.

[0029] In the picture:

[0030] Figure 1 A communication system according to an example embodiment is shown.

[0031] Figure 2 A method of determining a bus node sequence in a multi-drop communication bus according to an example embodiment is shown.

[0032] Figure 3 A method of resolving a bus node physical identifier according to an example embodiment is shown.

[0033] Figure 4 An apparatus according to an example embodiment is shown.

[0034] Figure 5 An elevator communication system according to an example embodiment is shown. DETAILED DESCRIPTION

[0035] Figure 1 A communication system according to an example embodiment is shown. The communication system includes a multi-point communication bus 108 and a plurality of bus nodes 100, 102, 104, 106. The bus nodes 100, 102, 104, 106 may include any device or system element configured to communicate via the multi-point communication bus 108. One of the bus nodes 100, 102, 104, 106 may serve as a measurement node 100. The multi-point communication bus may include, for example, a multi-point Ethernet bus. However, this is one possible implementation of the multi-point communication bus 108, and other implementations may also be used. The multi-point Ethernet bus 108 may include, for example, a 10BASE-T1S multi-point Ethernet bus.

[0036] Now combine Figure 2 and 3 The operation of the communication system is discussed in more detail.

[0037] Figure 2 A method of determining a sequence of bus nodes 100, 102, 104, 106 in a multipoint communication 108 bus according to an exemplary embodiment is shown. One of the bus nodes 100, 102, 104, 106 acts as a measuring node 100.

[0038] At 200, the measuring node 100 sends a request to a selected bus node (e.g., bus node 102) to set its network interface (e.g., a media dependent interface (MDI) in Ethernet) to a loopback mode using a physical identifier of the bus node. For example, the loopback mode may refer to a mode in which the loopback circuit of the network interface has a known low jitter delay characteristic. In an example embodiment, the request from the measuring node 100 may include timing information related to the loopback mode, which indicates the duration of the loopback mode. In another example embodiment, the bus node 102 may time itself according to a known pattern or timing. Furthermore, in another example embodiment, the constant delay loopback circuit may include an echo canceller and a repeater. Furthermore, impedance matching may be provided to prevent reflections of signals from the bus node.

[0039] The measuring node 100 may also set a detection method on the signal received from the bus node, ie for looping back the response signal. The measuring node 100 may also set an initial delay, before which the detector will not trigger the delay even if the previously set conditions are not met, until the initial delay expires.

[0040] At 202, the measuring node 100 is configured to transmit at least one signal to the bus node 102 via the multipoint communication bus 108. The at least one signal may include a single pulse or a specific pulse pattern. In addition to transmitting the at least one signal and if an initial delay is set, the measuring node 100 may be configured to start counting the initial delay. When the initial delay expires, the measuring node 100 will automatically start the timer. If the initial delay is not set in advance, the measuring node 100 directly starts the timer. The measuring node 100 can be configured to use a long delay line or some other similar technology to collect multiple samples of the reflected signal. When the timer is activated, the long delay line is ready to capture the response signal. Additionally or alternatively, the measuring node 100 can use an Ethernet transceiver of a physical layer (PHY) to send and receive signals.

[0041] At 204, the measuring node 100 is configured to receive at least one loopback response signal caused by the transmitted at least one signal from the bus node 102. In an example embodiment, the measuring node 100 may be configured to command the long delay line to capture the reflected signal, ie, the response signal.

[0042] At 206, the measuring node 100 is configured to measure a round trip delay between the at least one signal and the loopback response signal. In an example embodiment, the measuring node may start a timer when the at least one signal is sent to the node. When the loopback response signal is received, an interrupt is generated in the measuring node and the timer is stopped according to the interrupt. The round trip delay / round trip time can then be determined based on the timer value. Alternatively, the peripheral hardware can generate a signal to stop the timer after receiving the loopback response signal.

[0043] Steps 200, 202, 204 and 206 are repeated for each remaining bus node 104, 106, respectively.

[0044] At 208, the measuring node 100 is configured to solve the physical order of the bus nodes 102, 104, 106 in the multi-drop communication bus 108 based on the round trip delay. For example, the measuring node 100 can be configured to use the content of the initial delay, the timer, and the long delay line round trip time. Now, the measuring node 100 itself has a vector of physical identifiers and their distances in the time domain. Any known solution can be used to map the time domain to spatial distances.

[0045] Furthermore, when the loopback circuit has a predictable delay with very low jitter or variation, the distance between the measuring node and the bus node can be reliably determined for each bus node based on the round trip delay. The delay itself is not a problem, as long as the delay is known. Furthermore, in an example embodiment, at least one signal sent by the measuring node 100 may include a digital message. This means that the reliability of the physical order determination can be enhanced by, for example, applying a checking algorithm or correlation to the signals returned from the bus nodes.

[0046] In an example embodiment, statistical methods of repeated measurements may be used to improve accuracy and / or resolution. Error correction techniques applied to the signal may provide additional reliability. In addition, if the round-trip time measurement relies on the precise wave propagation speed through the multi-point communication bus, the absolute distance measurement may require additional steps (such as calibrating the cable type). However, approximate or relative distance measurements are still possible (assuming an average wave propagation speed, such as 6ns / m). In an example embodiment, by appropriately selecting system parameters, the diagram can be used to find cable connection points (stubs, branches), discontinuities in cables / harnesses, or changes in previously known good network conditions due to aging, mechanical stress, increased connector resistance, etc. In addition, in networks that rely on IEEE 802.3Clause 148, the test can be combined by scheduling the beacon transmission of the multi-point communication bus segment coordinator, which can avoid conflicts with normal traffic and increase the reliability of the system.

[0047] By using the solution shown above, enumeration and monitoring of the network can be performed without the need for additional hardware on the bus nodes, additional configuration during manufacturing / installation or additional wires / wiring.

[0048] Furthermore, by using the solution described above, not only the order of the bus nodes can be determined, but also their relative and / or absolute distances in the time domain or space domain. This makes it possible to determine even the layout or topology of the communication system by means of the solution of the invention.

[0049] Figure 3 A method of resolving a physical identifier of a bus node according to an example embodiment is shown.

[0050] At 300, a physical identifier allocation strategy is applied wherein the segment coordinator (eg, measurement node 100) uses exclusive physical identifiers wherein the bus nodes 102, 104, 106 will detect usage conditions using special physical identifiers associated with transmission opportunities.

[0051] At 302, the segment coordinator sets all bus nodes 102, 104 and 106 to a responding state, commanding them to respond to subsequent lookup request messages.

[0052] At 304 , the segment coordinator resolves the media access control addresses of the bus nodes 102 , 104 , 106 using at least one lookup request message.

[0053] At 306 , the segment coordinator queries the physical identifiers of the bus nodes 102 , 104 , 106 based on the media access control addresses of the bus nodes 102 , 104 , 106 .

[0054] At 308 , the segment coordinator assigns each bus node 102 , 104 , 106 a unique physical identifier.

[0055] In an example embodiment, steps 300-308 may involve three main components:

[0056] 1. Physical identifier (PHY-ID) allocation / reservation policy for segment coordinator (SC). SC can use PHY-ID 0.

[0057] 2. PHY-ID usage policy of the remaining (coordinating) nodes.

[0058] 3. PHY-ID Assignment Method: This algorithm can run inside or on top of the SC and allows enumeration of any unconfigured nodes (UN) that currently do not have a unique PHY-ID and assigning and allocating PHY-IDs to these nodes.

[0059] In the physical identifier allocation / reservation policy, PHY-ID #0 may be reserved for exclusive use by the SC. The SC may reserve another special PHY-ID (SPID) for use by any / all unconfigured nodes (UNs). The Transmission Opportunity (TO) belonging to this special PHY-ID (SPID) may be used by any (0-N) UNs. In practice, this may allow all nodes using the SPID to access the channel like a regular (default) Ethernet channel, where arbitration is handled by a "first-come, first-served" policy and conflicts are handled by a random back-off-retry method (CSMA / CD). The SPID may have a constant value (e.g., #1) or a varying value (e.g., the number of known unique PHY-IDs plus 1), depending on whether the configuration of the UN should take precedence over normal communication of ordinary nodes, or vice versa:

[0060] ——Method A. When using PHY-ID #1, the configuration of UN takes precedence over the normal message, and the SC assigns a unique PHY-ID starting from #2.

[0061] ——Method B. When using a variable PHY-ID, normal messages take precedence over the UN configuration, and the SC assigns a unique PHY-ID starting from #1, but it is also allowed to assign an additional TO for each PLCA cycle before transmitting the PLCA BEACON again.

[0062] Depending on local requirements, the SC may choose a hybrid strategy, for example, after power-up, method A may be used until all nodes receive a unique PHY-ID. After this, the SC may switch to method B or turn off additional TOs for certain parts (0-100%) of the PLCA cycle. In an example embodiment, the SC may also maintain multiple SPIDs to allow, for example, the assignment of PHY-IDs based on priority.

[0063] In the PHY-ID usage strategy, when a bus node detects one of the following conditions (for example, after a reset), it will start normal communication using the known SPID:

[0064] - The bus node does not have a unique PHY-ID, i.e. the bus node is an unconfigured node (UN)

[0065] - The bus node has one, but it will detect repeated / regular collisions on the TO it belongs to (which means that the PHY-ID is not uniquely owned by the bus node, which may indicate a configuration error).

[0066] In the PHY-ID assignment method, the SC can maintain its own algorithm to enumerate all nodes on the hybrid segment or allow higher layer / host protocols to run their own algorithms to achieve this. Such an algorithm can be, for example, as follows:

[0067] - Using L2 broadcast / multicast addressing services, the SC may set all bus nodes to the "Responding" state, commanding them to respond to any subsequent Lookup Request (FR) messages. If bus nodes are allowed to remember their PHY-IDs (e.g., via a local configuration database) or have locally configured PHY-IDs (e.g., via configuration pins, jumpers, rotary switches), the SC may need to stretch the PLCA cycle to the maximum PHY-ID allowed in the system (e.g., #255) to allow those pre-configured bus nodes to respond.

[0068] - Using L2 broadcast / multicast addressing services, the SC sends a lookup request message or a sequence of lookup request messages.

[0069] - The SC receives the first Lookup Answer (FA), which contains the MAC address of that bus node. At this stage, some / all bus nodes may not have a unique PHY-ID, so the SPID is used, as described above. This situation may cause physical conflicts (because the TO belonging to the SPID is operating in CSMA / CD mode), but this is to be expected and can be handled by standard normal random processes.

[0070] -SC commands the newly discovered node to no longer respond to subsequent search request messages.

[0071] - The SC repeats these steps until no bus node sends a Lookup Answer message. The SC then assumes that it holds the complete list of MAC addresses used on the multipoint bus segment.

[0072] - In an iterative manner, based on the previously collected MAC addresses of the nodes, the SC queries the PHY-IDs of all bus nodes using a unicast addressing service.

[0073] - The SC may run an algorithm that lists a contiguous (no holes) sequence of unique PHY-IDs and assigns these to nodes. This is done to minimize the number of PHY-ID reconfigurations (i.e. changes).

[0074] -SC may send network commands to bus nodes that require a new PHY-ID based on the MAC address. These messages set the bus nodes to start using the new PHY-ID immediately.

[0075] - When all nodes are passed, SC can run as a conflict-free hybrid segment with PLCA.

[0076] The solution demonstrated above can also be used to assign any type of PHY-ID pattern to a bus segment. This approach not only configures unconfigured nodes, but also eliminates unintended PHY-ID conflicts and unnecessary "holes" in the PHY-ID scheme that can cause network performance degradation or network performance degradation.

[0077] In an example embodiment, the functionality discussed above may be implemented, for example, by an integrated circuit.

[0078] Figure 4 A device 400 according to an example embodiment is shown. The device 400 may include at least one processor 402. The device 400 may also include at least one memory 404. The memory 404 may include program code 406, which when executed by the processor 402 causes the device 400 to perform at least one of the example embodiments discussed above. The example embodiments and various aspects of the subject matter may be included in any suitable device capable of performing the processes of the example embodiments. The example embodiments may also store information related to the various processes described herein. Although the device 400 is illustrated as a single device, it is worth noting that, where applicable, the functionality of the device 400 may be distributed to multiple devices. The device 400 may include, for example, Figure 1 A measuring node 100 is shown.

[0079] Example embodiments may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. Example embodiments may store information related to the various methods described herein. This information may be stored in one or more memories 404, such as a hard disk, an optical disk, a magneto-optical disk, a RAM, etc. One or more databases may store information for implementing example embodiments. Databases may be organized using data structures (e.g., records, tables, arrays, fields, graphs, trees, lists, etc.) contained in one or more memories or storage devices listed here. The methods described for example embodiments may include appropriate data structures for storing data collected and / or generated by the methods of the devices and subsystems of the example embodiments in one or more databases.

[0080] Processor 402 may include one or more general purpose processors, microprocessors, digital signal processors, microcontrollers, etc., programmed according to the teachings of the example embodiments, which will be appreciated by computer and / or software technicians. Based on the teachings of the example embodiments, programmers with ordinary skills can easily write appropriate software, which will be appreciated by those skilled in the software art. In addition, the example embodiments can be implemented by the preparation of application-specific integrated circuits or by connecting appropriate conventional component circuit networks, which will be appreciated by those who are proficient in the electrical art. Therefore, these examples are not limited to any specific combination of hardware and / or software. Stored on any one or combination of computer-readable media, the examples may include software for controlling components of the example embodiments, for driving components of the example embodiments, for interacting components of the example embodiments with human users, and so on. The computer-readable medium may also include a computer program for executing all or part of the processing performed in implementing the example embodiments (if the processing is distributed). The computer code device of the example may include any suitable interpretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynamic link libraries (DLLs), Java classes and applets, complete executable programs, and the like.

[0081] As described above, the components of the example embodiments may include a computer-readable medium or memory 404 for storing instructions written according to the teachings, and for storing data structures, tables, records, and / or other data described herein. In an example embodiment, the application logic, software, or instruction set is maintained on any of a variety of conventional computer-readable media. Within the scope of this document, a "computer-readable medium" may be any medium or means that can contain, store, communicate, propagate, or transmit instructions for use by or in connection with an instruction execution system, device, or equipment (such as a computer). A computer-readable medium may include a computer-readable storage medium that may contain or store instructions for use by or in connection with an instruction execution system, device, or equipment (such as a computer). A computer-readable medium may include any suitable medium that participates in providing execution instructions to a processor. Such a medium may have a variety of forms, including but not limited to non-volatile media, volatile media, transmission media, and the like.

[0082] Device 400 may include a communication interface 408 configured to enable device 400 to send and / or receive information to / from other devices, servers, and / or clients.

[0083] The device 400 may include means for performing at least one method described herein. In one example, the device may include at least one processor 402, at least one memory 404 including program code 406, and the program code is configured to cause the device 400 to perform the functions when executed by the at least one processor 402.

[0084] Figure 5 FIG. 1 shows an elevator communication system using a multi-point communication bus according to an exemplary embodiment. Figure 1-3 Functionality discussed.

[0085] The elevator communication system may include an elevator controller 500 . The elevator communication system may further include one or more multi-drop bus segments 512A, 512B, 512C, 518A, 518B, 518C reachable by the elevator controller 500, and a plurality of elevator system nodes 506A, 506B, 506C, 510A-510F, 515A, 514B, 514C, 516A-516F configured to communicate via the multi-drop bus segments 512A, 512B, 512C, 518A, 518B, 518C, wherein the elevator system nodes 506A, 506B, 506C, 510a-510b, 514C, 516a-516c, 516A-516F are reachable to the elevator controller 500 via the multi-drop bus segments 512A, 512B, 512C, 518A, 518B, 518C. In an example embodiment, the multi-point bus segment comprises a multi-point Ethernet bus segment.

[0086] In an example embodiment, the elevator communication system may include a point-to-point Ethernet bus 502 and at least one connection unit 504A, 504B, 504C, the connection unit including a first port connected to a multi-point bus segment 508A, 508B and a second port connected to the point-to-point Ethernet bus 502. Thus, by using the connection units 504A, 504B, 504C, one or more multi-point bus segments 508A, 508B may be connected to the point-to-point Ethernet bus 502. For example, the connection units 504A, 504B, 504C may refer to switches. In addition, the point-to-point Ethernet bus 502 may be connected to the elevator controller 500. The point-to-point Ethernet bus 502 may be, for example, a 100BASE-TX or 10BASET1L point-to-point Ethernet bus. The multi-point bus segments 508A, 508B, 512A, 512B, 512C, 518A, 518B, 518C may include, for example, a 10BASE-T1S multi-point Ethernet bus.

[0087] In an exemplary embodiment, the elevator system nodes 510A-510F, 516A-516F are configured to interface with at least one of an elevator fixture, an elevator sensor, an elevator safety device, and an elevator control device. In addition, in an exemplary embodiment, power to the nodes may be provided using the same wiring.

[0088] The elevator communication system may include an elevator safety controller. The elevator safety controller may be connected to the point-to-point Ethernet bus 502 via a connection unit. This means that the elevator system nodes 506A, 506B, 506C, 510A-510F, 514A, 514B, 514C, 516A-516F may send information to the elevator safety controller via the common point-to-point Ethernet bus 502 and vice versa. For example, the elevator system nodes 506A, 506B, 506C, 510A-510F, 514A, 514B, 514C, 516A-516F may send information from a sensor or a fixture to the elevator controller 500 or the elevator safety controller and receive information from it to control, for example, an actuator configures the fixture, etc. At least a portion of the elevator system nodes 506A, 506B, 506C, 510A-510F, 514A, 514B, 514C, 516A-516F may be safety nodes that comply with IEC61508 SIL level 3, having a safety processing unit and a separate communication controller. Data from the safety processing unit can only be sent to the elevator safety controller. The safety node may be configured to interface with an elevator safety device, such as a safety sensor or a safety contact indicating elevator safety, such as an elevator door contact, a door lock contact, an overspeed regulator contact, a buffer contact, etc. The safety node may be configured to communicate with the elevator safety controller. In order to establish safe communication, different types of data checks may be used in the communication, such as verification, error detection and / or correction algorithms, etc.

[0089] By using at least one point-to-point Ethernet bus and at least one multi-point Ethernet bus segment to implement communication within the elevator communication system, various segments can be formed within the elevator communication system. For example, elevator system nodes 510A, 510B can form a first floor station segment, elevator system nodes 510C, 510D can form a second floor station segment, elevator system nodes 510E, 510F can form a third floor station segment, hoistway nodes 506A, 506B, 506C can form a first hoistway segment, and hoistway nodes 514A, 514B, 514C can form a second hoistway segment. Each segment can be implemented using a separate multi-point bus.

[0090] like Figure 5As shown, the hoistway nodes 506A, 506B, 506C, 514A, 514B, 514C interconnect the hoistway segments 508A, 508B and the landing segments 512A, 512B, 512C, 518A, 518B, 518C, wherein the hoistway nodes 506A, 506B, 506C, 514A, 514B, 514C are connected to the hoistway segments. In other words, the hoistway nodes 506A, 506B, 506C, 514A, 514B, 514C may include or may serve as switches for the landing segments 512A, 512B, 512C, 518A, 518B, 518C. This may provide a simple solution for adding new elevator system nodes in the elevator communication system. This also enables a solution where a single elevator system node can act as a switch or repeater for another multi-point Ethernet bus segment, and nearby elevator system elements (such as call buttons, displays, destination operation panels, cameras, voice intercom devices, etc.) can all be connected to another multi-point Ethernet bus segment.

[0091] One or more of the plurality of elevator system nodes 506A, 506B, 506C, 510A-510F, 514A, 514B, 514C, 516A-516F may serve as the measurement node 100 discussed above.

[0092] While the essential novel features as applied to the preferred embodiments thereof have been shown, described and pointed out, it is to be understood that various omissions, substitutions and changes in the form and details of the apparatus and methods may be made by a skilled artisan without departing from the scope of the claims. For example, it is expressly intended that all combinations of these elements and / or method steps, performing substantially the same functions in substantially the same manner to achieve the same results, are within the scope of the disclosure. Furthermore, it should be recognized that structures and / or elements and / or method steps associated with any disclosed form or embodiment may be incorporated into any other disclosed or described or suggested form or embodiment as a general matter of design choice.

[0093] Applicants hereby disclose in isolation each individual feature described herein and any combination of two or more such features, as long as such features or combinations can be performed on the basis of this specification as a whole and according to the common general knowledge of a skilled person, regardless of whether such features or combinations of features solve any problem disclosed herein, and are not limited by the scope of the claims. Applicants indicate that the disclosed aspects / embodiments may include any such individual features or combinations of features. Based on the above description, various modifications may be made within the scope of the claims for those skilled in the art.

Claims

1. A method for determining a sequence of bus nodes (102, 104, 106) in a multipoint communication bus (108), one of the bus nodes acting as a measuring node, the method comprising: For each bus node (102,104,106): sending (200) a request to a bus node (102, 104, 106) by a measuring node using a bus node physical identifier to set the bus node (102, 104, 106) to a loopback mode; transmitting (202) at least one signal to a bus node (102, 104, 106) via a multi-drop communication bus (108) by a measurement node; receiving (204) a loopback response signal caused by at least one signal from a bus node (102, 104, 106) by a measurement node; and measuring (206) by a measuring node a round trip delay between the at least one signal and the loopback response signal, and solving (208) a physical order of bus nodes (102, 104, 106) in a multi-point communication bus (108) based on round trip delays of the measuring nodes, in, The multi-point communication bus (108) comprises a multi-point Ethernet bus.

2. The method of claim 1, wherein the bus node (102, 104, 106) comprises a constant delay loopback circuit.

3. The method of claim 2, wherein the constant delay loop back circuit comprises an echo canceller and a repeater.

4. The method according to any one of claims 1 to 3, wherein at least one signal is a single pulse or a pulse pattern.

5. The method according to any one of claims 1 to 4, wherein at least one signal is an analog signal.

6. The method according to any one of claims 1-5, wherein the request comprises timing information related to the loopback mode, the timing information indicating a duration of the loopback mode.

7. The method according to any one of claims 1 to 6, further comprising resolving the bus node physical identifier by: applying a physical identifier allocation strategy wherein a segment coordinator uses an exclusive physical identifier, wherein a bus node will detect a usage condition using a special physical identifier, the special physical identifier being associated with a transmission opportunity; Setting all bus nodes (102, 104, 106) to a response state by the segment coordinator, commanding them to respond to subsequent search request messages; Resolving a media access control address of a bus node (102, 104, 106) by a segment coordinator using at least one lookup request message; querying the physical identifier of the bus node (102, 104, 106) via the segment coordinator based on the media access control address of the bus node; and Each bus node (102, 104, 106) is assigned a unique physical identifier by the segment coordinator.

8. An apparatus configured to perform the method according to any one of claims 1-7.

9. The device according to claim 8, wherein: The apparatus comprises an integrated circuit configured to perform the method according to any one of claims 1-7.

10. The device according to claim 8, wherein: The apparatus comprises an elevator system node configured to perform the method according to any one of claims 1-7.

11. A communication system comprising: a multi-drop communication bus (108); and at least one bus node (102, 104, 106) communicatively coupled to the multi-point communication bus (108); It is characterized in that The communication system further comprises a device according to any one of claims 8-10, which is communicatively connected to the multi-point communication bus (108).

12. The communication system of claim 11, wherein the communication system comprises an elevator communication system.

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