DE102020200819A1 - Extension of a bus protocol with transfer of useful data in the header - Google Patents

Abstract

Master and slave, as well as a method for data transmission between a master and at least one slave via a bus with a protocol which has a header with an ID or address field. The whole or parts of the ID or address field (PID) are used to transmit a useful data or command.

Description

The invention relates to a method for expanding a bus protocol and a master and a slave.

State of the art

In the state of the art, there are various types of fieldbuses that meet different requirements and, depending on the application, must be optimized in terms of costs, data transmission rates, real-time requirements, etc. the LIN (Local Interconnect Network) Bus, which runs from LIN Consortium has been specified, serves as a cost-effective solution, particularly in the automotive sector, which enables or limits transmission speeds of up to 20 kbit / s. Another limitation is the delay time of 20 ms between two consecutive messages.

If it turns out, especially during an almost complete development or operation, that the data transmission rate is not sufficient, a different bus system would typically have to be used and, if necessary, hardware would have to be exchanged and redesigned at high cost.

As in DE102016105264A1 described in [0027], signaling / headers are usually transmitted separately from user data.

The GSM standard of mobile radio transmission teaches breaking this separation, since SMS messages are transmitted as part of the signaling. However, this does not apply to packet-switched field buses such as the LIN to.

Disclosure of the invention

A method for data transmission between a master and at least one slave via a bus with a protocol which has a header with an ID or address field and includes that the whole or parts of the ID or address field are used to transmit a useful data or command .

Bus, protocol, as well as master and slave are well-known terms from network technology. In the present case, master and slave can designate the logical communication units that are part (each) of an independent device and are either integrated into it, e.g. B. in which a microcontroller of the device provides the master or slave functionality or are designed as independent hardware units / modules.

In many protocols, the header is defined as part of a frame that precedes the actual user data and contains metadata, in particular an address in an address field, which specifies the slave for which the frame is intended. This is particularly necessary for a non-collision-free bus on which several slaves are listening in or transmitting at the same time. More details can be found in the respective protocol specification of the bus.

The term data denotes that which is normally (i.e. according to the specification of the protocol) not transmitted in the header but in the data fields following the header. The ID / address field is normally used to identify, address or address slaves. If the number of slaves is smaller than the number of addresses that can be addressed with the size of the ID / address field, then there are free / unused addresses, so to speak, that can be used for other purposes, namely to transfer data or commands.

An ordinary address field with a certain number of bits allows the addressing of a maximum number of slaves. However, the procedure described requires free addresses, i. H. an address space of the address field that is not used by the slaves to be addressed. These free addresses can be used for the usage data or commands.

Advantageously, under the conditions described, user data can already be transmitted in the header, which can be dispensed with later. Depending on the nature of the protocol, bit sequences or entire frames can be saved with the same amount of user data transmitted, which in turn increases the effective data throughput or the speed of the bus.

For data processing and (business) IT, data are defined as signs (or symbols) that represent information and that serve the purpose of processing and bring a benefit. This is where the term user data or usage date comes from. The term datum denotes the singular of data and can be used synonymously, since a useful datum or useful data consist equally of a number of bits. A distinction is only made on the basis of the logical assignment. A usage data can comprise a certain number of bits, e.g. B. be a byte, but also include fewer bits in the present exemplary embodiments. Payload data can comprise several units of a payload data.

When assigning the user data or command to the address field, depending on the layer model and approach, the user data that was originally transmitted in a higher layer (e.g. application layer) in the master and slave may be transferred to a lower layer must be brought to be packed in the address field.

In a further embodiment, the method comprises that the address field is divided up bit by bit and one group of bits is used for addressing, another group of bits for the useful data and optionally another group for a command to the addressed slave.

In other words: The ID or address field is divided into bits and a group of these bits divided in this way is used for addressing. Another group of bits is used either for the useful data or for a command to the addressed slave. If necessary, there can also be a third group, so that one group is available for addressing, another for the usage data and another for the command.

This type of use assumes that only a maximum of half the number of normally maximum possible slaves may be addressable in order to get at least one bit free (for this borderline case).

If the transmission of the useful data in the address field on the slave side already makes it clear what is to be done with this useful data, the (previously) necessary command for using this useful data can advantageously be superfluous. The value for the previously required command can then be assigned for another command or usage data. The usage data would then be logically independent of the address or the command transmitted in parallel.

A data item can be directed to a slave, but another slave is addressed in parallel, to which the data in the data field behind the header is directed. Alternatively, a slave can process the usage data in a certain way and receives a command in parallel for a further purpose.

In a further embodiment, the method comprises that communication is carried out between the master and precisely one slave.

This establishes a peer-to-peer connection (1: 1 relationship) and there is no need for addressing, since the recipient of the message is always unique (the same). The advantage of this bus structure is that all address bits can be used for the user data or command.

In a further embodiment, the method comprises that either values are transmitted in the ID or address field that represent commands or other values that represent the usage data.

In contrast to the previous exemplary embodiment, the focus here is no longer on separate groups of bits that contain different things.

Depending on the length of the address field, a certain number of different addresses can be named or such a number of values can be transferred in the address field. In the present case, an address is not necessary for a peer-to-peer connection; instead, the value range of the values in the address field is divided into a value range for commands and one for data. Depending on the definition that is technically implemented in the configuration of the system, it is agreed between the master and slave what which value means.

Usually, the two value ranges are chosen to be connected, but any fragmentation of the value ranges is also conceivable.

In this way, the entire value range of the address field can advantageously be used, even if the two value ranges do not coincide with the bit limits (2 to the power of x).

The usage date is quantified on the basis of the available range of values. Correspondingly, the transmitted data item can have as many quantization levels or different data values as there are values available in the address field that are not occupied by commands.

Any value that is not a command can be used as the data value of the payload. A data value then corresponds specifically to a corresponding physical value or a value that the master wants to send. A transcription table or conversion formula can be used to determine the data value that is then transformed back in the slave using a reciprocal conversion.

In a further embodiment, the method comprises that the usage data represents a value for a speed / speed specification and the slave receives this usage data for controlling a pump for a hydraulic fluid.

In this way, the overhead in the header for user data can advantageously be used to transmit the operating point request of the first control device to a second control device for an electrically driven pump, so that a higher Throughput of the user data and a better dynamic than before is achieved.

In a further embodiment, the method comprises that the usage data is sent more frequently than the command.

If the usage data and a parallel command cannot (or cannot) be sent at the same time, data transmissions and command transmissions must be scheduled (timed). In this way, application-related details can advantageously be implemented in the process.

In a further embodiment, the method comprises that the usage data for the rotational speed is transmitted more frequently than a command to query the diagnostic data and, at the same time, this command is transmitted more frequently than a command to query the operating temperature.

In this way, the (set) speed of the pump is updated frequently and promptly, while the less frequently required diagnostic data is requested from the pump less often. The operating temperature needs to be transmitted even more rarely, as it does not change as quickly.

In a further embodiment, the method comprises that the underlying protocol is the LIN protocol (Local Interconnect Network). The ID or address field corresponds to the Protected Identifier Field, as specified in the specification of the bus.

In particular, the standardized LIN protocol can be expanded or modified as described.

The LIN protocol is structured in such a way that the idea described can advantageously be used well. The speed specification, which was previously transferred to the data field following the header, can now be transferred to the remaining object IDs as values for the Protected Identifier Field, i.e. H. those Object IDs or values that are not occupied by commands are divided and the delay time is reduced.

Since the header is always specified by the master, the speed specification can no longer only be changed in every second message, but now in every message. This is possible because a usage data can now be accommodated in the header and consequently a data field for this usage data can be dispensed with. This can advantageously lead to the delay time being halved.

The advantage comes above all on buses with severe restrictions (such as the LIN with its 20 kbit / s) to wear. If the limit of the transmission capability is reached during a development, this can be extended by means of the invention without using a more complex bus, such as the CAN.

Furthermore, a first control unit for a transmission includes a master for executing the described method.

The control device advantageously has a master that implements the method / protocol described and sends headers with address fields that contain usage data.

Furthermore, a second control unit for an electrically driven pump has a slave for carrying out the described method. The pump can for example be a hydraulic pump.

The slave of the second control device can advantageously interpret the ID or address fields with the usage data.

Further exemplary embodiments are described and explained in more detail below with reference to the accompanying figures.

• 1 eine Steuergeräteanordnung;
• 2a eine Netzwerkstruktur eines Busses;
• 2b eine Aufteilung eines Protected Identifier Fields PID eines ersten Ausführungsbeispiels;
• 3a eine Netzwerkstruktur eines Busses einer Peer-to-Peer Verbindung;
• 3b eine Transkriptionstabelle für das Protected Identifier Field PID eines zweiten Ausführungsbeispiels;
• 3c eine Übersetzungstabelle eines dem Slave zugeordneten Geräts;
• 4 eine Abfolge von Nachrichten/Frames auf dem Bus.

Show it:

• 1 a control device arrangement;
• 2a a network structure of a bus;
• 2 B a division of a Protected Identifier Field PID a first embodiment;
• 3a a network structure of a bus of a peer-to-peer connection;
• 3b a transcription table for the Protected Identifier Field PID a second embodiment;
• 3c a translation table of a device associated with the slave;
• 4th a sequence of messages / frames on the bus.

1 shows a control device arrangement with the arrangement of a transmission G, which is a first control device EGS , e.g. B. includes a transmission control unit or electronic gear shift or is controlled by this. The transmission G can be used in a vehicle drive train. The first control unit EGS in turn includes a master M. , the one for the communication of the first control unit EGS over a bus B. responsible for.

Furthermore, the arrangement of control devices shows a pump P, which is a second control device SGP includes or is controlled by this. The pump P can be an electrically driven pump P for be the fluid supply of a hydraulic system of the transmission G, z. B. an "Integrated Electric Pump (IEP)" or an "Electric Machine (EM)" of a "Power Split Pump Drive (LVP)", as it is, for example, in the text DE102018206287A1 is described. The second control unit SGP in turn includes a slave S. , the one for the communication of the second control unit SPG via the bus B. responsible for.

About the bus B. becomes a message or frame with a header H transferring an ID or address field ID contains. In the ID or address field ID become commands Command X and / or a usage date Data Value X transfer. Depending on the protocol, the transmission takes place from the master M. to the slave S. instead of.

The following exemplary embodiments are shown based on the specification of the LIN bus. The ID and address field ID corresponds to the Protected Identifier Field PID . Examples of commands Command X are the commands 1-11 Command 1-11 and examples of payload Data Value X are the user data 1-53 Data Value 1-53 .

A first embodiment is shown in 2a and 2 B shown. 2a shows a possible network topology of a bus B. with a master M. and several slaves S ₁ -S ₄ .

1. 1. Bits für die Adressangabe A₀ , A₁ . Da gemäß 2a vier Slaves S₁-S₄ angeschlossen sind, genügen zwei Bits für deren Adressierung.
2. 2. Die restlichen Bits können als Datenbits D₀, D₃ zur Verfügung gestellt werden, mit deinen ein Nutzdatum Data Value X übertragen werden kann.

2 B shows a Protected Identifier Field PID a LIN bus, as it is e.g. B. in the S standard "LIN Specification Package Revision 2.2A" from December 31, 2010 is described in chapter 2.3.1.3. Start, stop and parity are standard in the LIN bus P ₀ , P ₁ bits are defined. The 6 bits 100-105 defined in the standard, which are defined for the frame identifier, are now defined as follows, going beyond the standard:

1. 1. Bits for address specification A ₀ , A ₁ . Since according to 2a four slaves S ₁ -S ₄ are connected, two bits are sufficient for their addressing.
2. 2. The remaining bits can be made available as data bits D ₀ , D ₃ , with your usable data Data Value X can be transferred.

The more slaves S ₁ -S ₄ are present and therefore the more bits are used for addressing A ₀ , A ₁ have to be kept in reserve, the fewer bits stand for the useful data Data Value X to disposal. The example can be transferred in the same way for any other number of slaves S ₁ -S ₄ . However, a maximum of 2 ^n-1 slaves (n = 6 for the Project Identifier Field PID from LIN ) be involved so that at least one bit is free for data use.

• - Daten- und Adressbits auch in einer anderen Reihenfolge angeordnet werden;
• - auf das Bit A₀ verzichtet werden, d. h. dies bleibt immer 0, so dass die verbotenen Werte nie entstehen, dafür kann das Bit aber nicht genutzt werden;
• - der LIN, bzw. der Master M so konfiguriert werden, bzw. der Wertebereich des Nutzdatums Data Value X so gewählt werden, dass besagte verbotene Werte nicht entstehen.

Please note that the Protected Identifier Field PID according to the specification in version 2.2 may not accept the forbidden values 0x3C to 0x3F. In order to adhere to the specification, it must be functionally ensured that no combinations of address and data bits occur that result in these forbidden values. To avoid this, z. B .:

• - Data and address bits can also be arranged in a different order;
• - on the bit A ₀ can be omitted, ie this always remains 0, so that the forbidden values never arise, but the bit cannot be used for this;
• - the LIN , or the master M. configured in this way, or the value range of the useful data Data Value X be chosen in such a way that said prohibited values do not arise.

It is also possible to provide command bits in addition to address and data bits, i.e. 3 groups of bits.

The usage date Data Value X can from one of the slaves S ₁ -S ₄ can be further processed directly, e.g. B. by showing the equivalent of a physical value Phys . Value contains or the value range for the input parameter of the with the slave S. connected device, e.g. B. a pump P, or the associated function. Alternatively or additionally, however, the value can also be converted or converted, as in a translation table in 3c shown.

A second embodiment is shown in 3a until 3c shown. 3a shows a possible network topology of a bus B. with a master M. and exactly one slave S. , creating a so-called peer-to-peer connection.

3b shows a possible transcription table for the content of the Protected Identifier Field PID a LIN bus with a standard 6-bit length. The address is omitted here, instead a first value range is used for commands Command 1 to command 11 to one slave S. intended. The values 0x0 to OxOA are used as an example. Further values 0x0B to 0x3B represent, for example, a second value range around different data values Data Value 1 to data value 53 of a useful data Data Value X transferred to.

In a Protected Identifier Field PID of an associated frame, unlike in the first exemplary embodiment, either a command Command X or a usage date Data Value X transmitted, but not both in parallel in the same frame. According to this example, it becomes a usage date Data Value X transmitted in the header can be transferred to a subsequent data field, as described in section 2.3.1.4 of the above specification, to add the usage date Data Value X to transmit, be waived since this already in the header H via Protected Identifier Field PID happened. The master M. can after the header has been sent H therefore start sending a new frame immediately, ie ahead of time compared to the standard.

In 3c a translation table is shown with the help of which the user data 1-53 Data Value 1-53 transferred to a range of values that the slave S. assigned second control unit SGP can further process. These values to be further processed can e.g. B. a physical equivalent, i.e. physical values Phys . Value 1 - 53 of a setpoint, e.g. B. operating / working point, or bit pattern for controlling the device, z. B. Pump P, for setting the by the usage date 1-53 Data Value 1-53 represented value.

This reverse translation is in the second control unit SGP carried out.

Depending on the application, that many bits can be used for transmission, e.g. B. complete, usually the header H The following data fields, as described, can be saved and the date of use 1-53 Data Value 1-53 be transmitted anyway. This can increase the bandwidth for these applications.

A hybrid of the exemplary embodiments 1 and 2 is also conceivable. More than one slave can do this S. be addressed by means of the method from the second embodiment, by z. B. certain values from the value range of the Protected Identifier Fields PID configured as intended for a first slave S ₁ , other values for a second slave S ₂ , etc.

In a more specific form of the second exemplary embodiment, the master is M. Part of a first control unit EGS a transmission G, in particular a transmission which is used in a vehicle drive train. The slave S. is part of a second control unit SGP , which is assigned to an electrically driven pump P. The master M. either sends inquiries about the status or diagnostics as commands Command X to the slave S. or payload Data Value X which correspond to a speed specification for pump P. There is no need for a separate header H The following data field can be used more for the speed specification, but speed specifications can be transmitted more frequently, since the part of the data frame that is customary according to the standard can be omitted. The command Command X there is no need to set the speed since the user data is transferred Data Value X implies the command and the resulting free value for another command Command X or use date Data Value X can be used.

• 0x00: Anforderung der Diagnosedaten
• 0x01: Anforderung der Betriebstemperatur
• 0x02: Anforderung der aktuellen Drehzahl
• 0x10: Setzen der Drehzahl auf Stillstand
• 0x01: Setzen der Drehzahl auf Geschwindigkeit 1
• 0x02: Setzen der Drehzahl auf Geschwindigkeit 2
• 0x03: Setzen der Drehzahl auf maximale Geschwindigkeit

For this scenario the transcription table of the Protected Identifier Fields PID field could look like this:

• 0x00: Request for diagnostic data
• 0x01: Request for the operating temperature
• 0x02: Request for the current speed
• 0x10: Setting the speed to standstill
• 0x01: Set the speed to speed 1
• 0x02: Set the speed to speed 2
• 0x03: Setting the speed to maximum speed

If the functional arrangement used in the concrete form of the second exemplary embodiment were to be used in a hybrid manner with the bit-by-bit division of the first exemplary embodiment, ie the command Command X would in the address bits A ₀ , A ₁ are coded and the date of use Data Value X in the data bits D ₀ to D ₃ , a command could advantageously be carried out at the same time Command X and a usage date Data Value X be transmitted. Disadvantageously, however, only a few different values for user data may then be possible Data Value X because the value range of the bits used for the respective group (always a power of two) may be larger than the value range actually used.

In 4th an exemplary sequence of frames for the concrete form of the second exemplary embodiment is shown, which is via the bus B. be transmitted. Thereby the commands Command X and data Data Value X sent depending on the required frequency. For example, diagnostic data ( diagnosis A. ) can be queried relatively frequently (e.g. every 100 ms) while the operating temperature ( diagnosis B. ) is queried less frequently (e.g. every 1 s). Since one frame can be sent per time unit (e.g. every 20 ms), the other places for frames for setting the speed ( set Data ) are used, ie these then appear relatively frequently. The precise application-related determination of the schedule (scheduling) is specified in the configuration.

List of reference symbols

EGS

First control unit

SGP

Second control unit

H

Header

M.

master

S, S1-S4

Slave (s)

B.

bus

ID

ID or address field

PID

Protected Identifier Field

A0, A1

Group of bits, address bits

D0-D3

Another group of bits, data bits

P0, P1

Parity bits

Command X

command

Data Value X

Usage date

Reserved for LIN

Reserved according to the LIN protocol

Command 1-11

Commands 1-11

Data Value 1-53

Use date 1-53

Phys. Value 1-53

Physical value 1-53

Set data

Usage date transmission

Diagnosis A

Query of the diagnostic data

Diagnosis B

Query of the operating temperature

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102016105264 A1 [0004]
• DE 102018206287 A1 [0046]

Non-patent literature cited

• standard "LIN Specification Package Revision 2.2A" from December 31, 2010 [0050]

Claims (10)

Method for data transmission between a master (M) and at least one slave (S, S ₁ -S ₄ ) via a bus (B) with a protocol which has a header (H) with an ID or address field (ID), thereby characterized in that the entire ID or address field (ID) or parts of the ID or address field (ID) are used to transmit a data value (Data Value X) or a command (Command X). Procedure for data transmission in accordance with Claim 1 , characterized in that the ID or address field (ID) is divided into bits (A ₀ -A ₁ ; D ₀ -D ₃ ) and a group of these bits (A ₀ -A ₁ ) divided in this way is used for addressing, while another group of bits (D ₀ -D ₃ ) is used either for the useful data (Data Value X) or for a command (Command X) to the addressed slave (S ₁ -S ₄ )). Procedure for data transmission in accordance with Claim 1 or 2 , characterized in that communication between the master (M) and exactly one slave (S) is carried out. Procedure for data transmission in accordance with Claim 3 , characterized in that either values are transmitted in the ID or address field (ID) that represent commands (Command X) or other values that represent the useful data (Data Value X). Method for data transmission according to one of the preceding claims, characterized in that the useful data (Data Value X) is sent more frequently than the command (Command X). Method for data transmission according to one of the preceding claims, characterized in that the useful data (data value X) represents a value for a speed and the slave (S) represents this useful data (data value X) for controlling a pump (P) for a hydraulic fluid receives. Procedure for data transmission in accordance with Claim 6 , characterized in that the usage data (Data Value X) for the speed is transmitted more frequently (Set Data) than a command to query the diagnostic data (Diagnosis A) and, at the same time, this command is transmitted more frequently than a command to query the operating temperature ( Diagnosis B). Method for data transmission according to one of the preceding claims, characterized in that the underlying protocol is the LIN (Local Interconnect Network). First control device (EGS) for a transmission (G), the first control device (EGS) having a master (M) for carrying out the method according to one of the Claims 1 until 8th . Second control device (SGP) for a pump (P), the second control device (SGP) having a slave (S) for carrying out the method according to one of the Claims 1 until 8th .

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