WO2022268444A1

WO2022268444A1 - Master/slave network and method for operating a master/slave network

Info

Publication number: WO2022268444A1
Application number: PCT/EP2022/064609
Authority: WO
Inventors: Thomas Sauer
Original assignee: ebm-papst neo GmbH & Co. KG
Priority date: 2021-06-24
Filing date: 2022-05-30
Publication date: 2022-12-29
Also published as: DE102021116389A1; EP4360264A1

Abstract

The invention relates to a master/slave network and to a method for operating same. The master/slave network has a bus line (11) to which a slave (12) or multiple slaves (12) and a splitter (14) are connected. Each slave (12) has a slave storage device (16) on which different pieces of current data (D1, D2,... Dn) are stored, and the splitter (14) has a splitter storage device (17). The communication between the splitter (14) and the at least one slave (12) via the bus line (11) is preferably based on a serial communication protocol. Multiple masters (15) are connected by means of the splitter (14) for communication purposes. The splitter (14) repeatedly updates the data (D1, D2,... Dn) on the slave storage devices, preferably at regular intervals, and provides said data (D1, D2,... Dn) on the splitter storage device (17). Thus, it is possible to process requests (A1, A2) from the masters (15) for at least one part of the data (D1, D2,... Dn) in a temporally parallel manner by means of the splitter (14). A forwarding of the requests (A1, A2) to the slaves (12) is omitted.

Description

ebm-papst neo GmbH & Co. KG June 24, 2021 Bachmühle 2 EBMP PO17 WO prrn 74673 Mulfingen Keyword:

Modbus splitter

Master-slave network and method of operating a master-slave network

The invention relates to a master-slave network with a bus line to which at least one participant is connected, which forms a slave. Current data is available in each slave. At least indirectly, a participant that forms a master is connected to the bus line. If necessary, the master can send a request to a slave to query its data, in particular the current data in a volatile memory, such as a register of the slave.

[0002] If communication takes place via the bus line using a serial protocol, only one master can access the bus line at a time. If several masters send requests via the bus line at the same time, communication conflicts can occur on the bus line.

For a serial communication protocol, e.g. the Modbus communication protocol, solutions are known to enable the connection of several masters. For example, the company ADFweb.com S.r.L. a master-multislave converter for use with a Modbus (product designation HD67146). This makes it possible to integrate several masters into the master-slave network.

A disadvantage of the previously known solutions is that at least temporally overlapping requests the requests are processed sequentially by several masters of the splitter or hub according to the time of receipt, which can lead to large time delays in the transmission of the response to a request.

Based on the prior art, it is an object of the present invention to improve the integration of multiple masters in a master-slave network.

[0006] This object is achieved by a master-slave network having the features of patent claim 1 and a method for operating a master-slave network having the features of patent claim 9.

The master-slave network has a bus line to which at least one slave and in particular a plurality of slaves are connected. A slave can be a field device, for example. Each slave has a slave memory. The slave memory can be a register of a processor, a cache memory or another memory in which current, changeable data of the slave is stored, for example current operating data. In the slave memory, for example, measurement data can be stored be contained by sensors of the slave or field device. The slave memory is in particular a volatile memory, for example a volatile semiconductor memory.

A splitter is communicatively connected to the bus line, preferably exactly one splitter. The communi- cation between the splitter and the at least one slave is based on a defined communication protocol, in particular a serial communication protocol, such as for example the Modbus protocol. For connection to the bus line, each slave and the splitter preferably have a serial interface, for example an RS-485 interface.

The master-slave network also includes several masters, each of which is connected to the splitter for communication. The communication link between the splitter and the masters can be based on any topology. The communication protocol of the communication between the masters and the splitter can correspond to the communication protocol of the communication via the bus line, but can also be different. The masters are only connected via the splitter and not directly to the bus line.

[0010] The splitter can also be referred to as a hub and is set up to process requests from the master in order to improve network communication and, in particular, to speed it up. For this purpose, the splitter has a splitter memory in which data are made available for transmission to the master. The splitter is set up to update the data content of the splitter memory regularly, so that the data content of the splitter memory after updating with the data in the we least one slave memory and in particular the multiple slave memories matches that there were saved at the time of the update.

Thus, the entire database of all IN ANY which slave memory is provided for access or transmission to the master in the splitter. The splitter can update its database cyclically. requests for at least part of the data from the one slave or several existing slaves can be answered directly by the splitter. A request from a master that arrives in the splitter is therefore not forwarded to the slaves and their response does not have to be waited for and forwarded to the requesting master. The splitter is thus able to process requests from two or more masters with a time overlap or at the same time. As a result, the average latency or response time between receiving a request from a master and transmitting a response to this request can be significantly reduced compared to previous solutions.

In a preferred embodiment, a standardized, serial communication protocol can be used for communication between the splitter and the at least one slave. The communication protocol does not have to conform to a de jure standard, but can also be a de facto standard, as can be the case with the Modbus communication protocol. In one embodiment, the communication protocol can correspond to the communication protocol "Modbus-TCP" or "Modbus-RTU" defined in IEC 61158.

In particular, the communication protocol only allows serial communication via the bus line.

Each slave can be a field device. The field device can have at least one actuator and/or at least one sensor. In one embodiment, at least one of the field devices is a fan. A field device may have a sensor or solely by one Be formed sensor, for example, a pressure sensor, egg nen volume flow sensor or a temperature sensor. A field device can, for example, also have a control device or be formed by a control device, such as a valve, a throttle or an adjustable flap of a room air system. All field devices or slaves can be part of a common system, for example a room air system or heating system or building management system or a common air conditioning system.

The splitter is preferably set up to answer multiple requests from multiple masters for data from one slave or from multiple slaves at least at times or in phases at the same time. In this way, inquiries can be processed and answered in parallel in the splitter.

In a preferred embodiment, the splitter is set up to repeatedly copy the data from all existing slave memories, in particular cyclically, partially or completely. The splitter can be set up, for example, to repeatedly and in particular cyclically compare the data in the splitter memory with the data in the at least one slave memory and only copy changed data. It is also possible for the splitters and/or the masters to be set up to define the data and/or memory contents to be transmitted as part of the requests. For this purpose, a setting option could be present in the masters and/or in the splitter, which defines, for example, certain memory locations or registers in the at least one slave, the contents of which are sent to at least one of the Mater are to be transmitted. The repeated updating or copying of the data from the existing slave memories can then be restricted to the defined data in the slave memories, which further improves the efficiency of data updating. The database in the splitter memory can be updated with all the options mentioned.

[0017] A method according to the invention for operating a master-slave network can use any embodiment of a master-slave network described above. At least the master-slave network has the bus line, one or more slaves, a splitter and several masters. The masters are only indirectly communication-connected to the at least one slave via the splitter and the bus line. The method according to the invention works as follows:

The splitter regularly compares the data provided in the splitter with the data in the at least one slave, with the database in the splitter being able to be changed at least partially so that after the update, the data content in the splitter corresponds to the data content in the at least one slave . If the splitter receives a request from a master or from several masters, this request is not forwarded to the relevant slave or slaves, but is processed in the splitter. In response to the request, the splitter transmits the requested data from its own database to the master that transmitted the request. As already explained, requests from several masters can be processed in parallel in the splitter. [0019] Advantageous embodiments of the invention result from the dependent patent claims, the description and the drawings. In the following, preferred exemplary embodiments of the invention are explained in detail with reference to the accompanying drawings. In the drawings show:

[0020] FIG. 1 shows a block diagram of an exemplary embodiment of a master-slave network,

[0021] FIG. 2 shows a schematic processing of requests from multiple masters based on a method according to the invention,

Figure 3 is a schematic representation of the flow of requests from multiple masters in a master-slave network according to the prior art and

FIG. 4 shows a schematic representation of the provision of data in the splitter for a number of masters connected to the splitter.

In Figure 1, a block diagram of an embodiment of a master-slave network 10 is shown schematically. The master-slave network has a bus line 11. A plurality of slaves 12 are each connected to the bus line 11 via a bus interface 13. FIG. In the exemplary embodiment, the bus interface 13 is a serial interface, for example of the RS-485 type.

A hub or splitter 14 is also connected to the bus line. For this purpose, the splitter 14 can have the same bus interface 13 as the slaves 12. The splitter 14 is communicatively connected to the slaves 12 via the bus line 11 . The communication corresponds to a standardized communication protocol, for example a serial communication protocol. The communication protocol can, for example, correspond to the Modbus standard or another serial communication standard. For example, in one embodiment, the communication protocol "Modbus TCP" defined in IEC 61158 may be used.

Several masters 15 are communicatively connected to the splitter 14, for example via a wired or wireless communication link. Each master 15 can be directly connected to the splitter 14 for communication via a separate communication link. There is no direct communication link between the masters 15 and the slaves 12 . The connection between the masters 15 and the bus line 11 is finally realized indirectly via the splitter 14 .

The communication between the masters 15 and the splitter 14 can be based on any suitable communication protocol and need not correspond to the serial communication protocol used for communication between the splitter 14 and the slaves 12 over the bus line 11.

At least the slaves 12 and at least one of the masters 15 of the master-slave network 10 can be part of a building management system, a room ventilation system, a heating system, an air conditioning system, etc., for example. The slaves 12 can, for example each be formed by a connected to the bus line 11 Nes field device, the field devices depending on the application have different functions and under different configurations. For example, a slave 12 or a field device can have at least one actuator and/or at least one sensor. An example of a field device is a fan, a pump, a valve, an actuator for a throttle or flap or the like, each with or without at least one associated sensor.

The number of slaves 12 can vary. The master-slave network 10 has at least one and preferably a plurality of slaves 12 . The number of splitters 14 and the master 15 connected to a common splitter 14 can also vary from the exemplary embodiment shown and described.

Each slave 12 has a slave memory 16, in particular a volatile memory. The slave memory 16 can be a volatile semiconductor memory, for example. In the exemplary embodiment, the slave memory 16 is formed by a register memory of a processor of the respective slave 12. Each slave memory 16 contains variable Liche data D1, D2, Dn, which characterize the current and/or desired operating state of the respective slave 12. For example, the data can contain target values, actual values, variably specified parameters, and so on.

The splitter 14 has a splitter memory 17, which can also be designed as a volatile semiconductor memory, for example. The splitter 14 is set up to repeatedly and in particular cyclically update the splitter memory 17 and to update the data D1, D2, . . . Dn from the slave memories 16 to the splitter memory 17 to copy. As part of the update, the splitter 14 can copy all data D1, D2, ... Dn from all slave memories 16 into the splitter memory 17 or it can only read the data from the slave memories 16 and into the splitter -Copy memories 17 that have changed since the previous update. A further alternative for data update is to copy only a part of the total available data defined in the masters 15 and/or the splitter ter 14 as part of the update from the slave memories 16 to the splitter memory 17 . After the update, the splitter memory 17 contains the data D1, D2,...Dn from the slave memories 16, which were stored there at the time of the update.

Current data D1, D2, . . . Dn are thus available in the splitter memory 17 for transmission to the master 15. As is shown schematically in FIG. 4, the masters 15 therefore do not have to communicate with the slaves 12 in order to query their data, but can limit the communication to the splitter 14.

Figure 2 shows a schematic example of the process for a first request A1 from a master 15 (master 1) and a request A2 from a further master 15 (master 2), which is sent from the respective master 15 to the splitter 14 be transmitted. At the time when the first request A1 is received in the splitter 14, the data D1, D2,...Dn are being processed in the splitter memory 17, for example updated . It goes without saying that the first request A1 can also be received at a different point in time. After the data in the splitter memory 17 has been updated, the second request A2 is received. The second query A2 could also have arrived at an earlier point in time. What is essential in the method according to the invention is that the splitter 14 is set up to process the two queries A1, A2 in parallel in terms of time. Since all the data D1, D2, ... Dn of the slaves 12 are available in the splitter 14, the queries Al, A2 must not be forwarded to the slaves 12 and their response awaited, but can be in the splitter

14 itself edited and a corresponding response to the first request Al to a master 15 (first master Ml) and a response to the request A2 to the other master

15 (second master M2) are transmitted.

This procedure allows the average time delay or latency between receiving a request from one of the masters 15 and the transmission of a response to the relevant master 15 by the splitter 14 to be reduced.

If one of the masters 15 transmits a write command to the splitter 14, the write command (data transmission from the master 15 to at least one of the slaves 12) is forwarded by the splitter 14 as quickly as possible to the at least one affected slave 12 in order to Master 15 to store transmitted data in the slave memory 16 of the Sla ves 12.

In comparison, FIG. 3 shows a schematic representation of the sequence in an embodiment of the master-slave network according to the prior art. The requests A1, A2 of the master 15 are not processed in the splitter 14 in the prior art according to FIG. Because of the serial communi- cation via the bus line 11, the second request A2 received from the splitter 14 after the first request Al is initially not forwarded, but instead it is awaited until the slave or slaves 12 processes the first request Al and sends a corresponding response have the splitter 14 transmitted. After the splitter 14 has forwarded the answer to the query Al to a master 15 (first master M1), the second query A2 is then subsequently forwarded to the relevant slave or slaves 12 for processing. After the second request A2 has been processed by the slave(s) 12, the splitter 14 receives the response to the second request A2 and forwards it to the other master 15 (second master M2). It is clear that there can be greater time delays between a query (for example second query A2) and the corresponding response compared to the method according to the invention, as illustrated schematically by way of example in FIG. 2 and explained above.

The invention relates to a master-slave network and a method for its operation. The master-slave network has a bus line 11 to which a slave 12 or more slaves 12 and a splitter 14 are connected. Each slave 12 has a slave memory 16 in which variable current data D1, D2,...Dn are stored. The splitter 14 has a splitter memory 17. The communication between the splitter 14 and the at least one slave 12 via the bus line 11 is preferably based on a serial communication protocol. Multiple masters 15 are communicatively connected to the splitter 14 . The splitter 14 updates the data D1, D2, . . . This makes it possible for requests A1, A2 from the master 15 to be processed in parallel by the splitter 14 for at least one part of the data D1, D2, . . . Dn. Forwarding the inquiries A1, A2 to the slaves 12 is omitted.

List of references:

10 master-slave network

11 bus line

12 slaves

13 bus interface

14 shards

15 masters

16 slave memories

17 splitter memories

Al first request

A2 second request

Dl-Dn data Ml first master

M2 second master t time

Claims

Patent Claims:

1. Master-slave network (10) comprising:

- a bus line (11),

- at least one slave (12) communicating with the bus line (11), each slave (12) having a slave memory (16),

-One with the bus line (11) kommunikationsverbunde NEN splitter (14), which has a splitter memory (17) and is set up to regularly update the splitter memory (17) to the time of the update currently in the at least one slave memory (16) to provide existing data (Dl, D2,...Dn) in the splitter memory (17), -several masters (15) connected to the splitter (14) for communication, the splitter (14 ) To set up is directed at the request of a master (15) or several masters (15) at least part of the data in the splitter memory (17) (Dl, D2, ... Dn) from the splitter (14) to the master (15) or the master (15) to transmit.

2. Master-slave network according to claim 1, wherein the communication between the splitter (14) and the at least one slave (12) via the bus line (11) takes place on a standardized communication protocol.

3. Master-slave network according to claim 2, wherein the communication protocol is directed to a serial communication.

4. Master-slave network according to one of the preceding claims, wherein the slave memory (16) of the at least one slave (12) and/or the splitter memory (17) is a volatile memory.

5. Master-slave network according to one of the preceding claims, wherein the slave memory (16) of the at least one slave (12) and / or the splitter memory (17) is a semiconductor memory.

6. Master-slave network according to one of the preceding claims, wherein each slave memory (16) is a cache memory or register memory of the respective slave (12).

7. Master-slave network according to one of the preceding claims, wherein the splitter (14) is set up to multiple requests (A1, A2) of multiple masters (15) to data

(Dl, D2, ... Dn) of the at least one slave (12) to process in parallel.

8. Master-slave network according to one of the preceding claims, wherein the splitter (14) is set up to repeat the data (Dl, D2, ... Dn) from all existing slave memories (16) partially or completely to copy.

9. Method of operating a master-slave network

(10) comprising a bus line (11), at least one with the bus line (11) communicatively connected slave (12), one with the bus line (11) kommunikationsver connected splitter (14) and at least two with the Splitter (14) communication-connected master (15) where the method comprises the following steps:

-Regular updating of the splitter (14) provided data (Dl, D2, ... Dn), to the time point of the update currently in the at least one slave memory (16) existing data (Dl, D2,. .. Dn) in the splitter memory (17);

- Transmitting at least part of the splitter

(14) provided data (Dl, D2, ... Dn) to one o- the multiple master (15) through the splitter (14) in response to a request from a master (15) or multiple masters (15).