KR20020042139A - Method for message frame operation of can system - Google Patents

Abstract

PURPOSE: A method for operating a message frame in a CAN(Controller Area Network) system is provided to enhance the field configuration system of a CAN message frame in a car so that each controller can recognize a data transmitted/received location only with the identifier field of a CAN message frame. CONSTITUTION: A user segments an identifier field into 3 field domains such as a destination field, a source field and an order field(ST21) and defines priority for the CAN data of each controller in accordance with the segmented field domains(ST22). The user defines priority for the internal CAN data for each controller according to the defined CAN data priority(ST23). Based on the defined CAN data priority of each controller, a transmitting side controller configures an identifier(ST24). If the transmitting side creates a CAN message frame, the transmitting side controller transmits the message frame through a CAN bus(ST25). The CAN message frame transmitted through the CAN bus is received by a controller that the destination field appoints(ST26).

Description

Message frame operation method of CAN system {METHOD FOR MESSAGE FRAME OPERATION OF CAN SYSTEM}

The present invention relates to a method of operating a message frame of a CAN system (hereinafter, abbreviated as CAN system), and more particularly, to a message frame of a CAN system for controlling each controller in a vehicle. It's about how.

In general, the CAN system provides a CAN bus which is a path for data exchange between various controllers provided in a vehicle, and adjusts the priority of data exchanged through the CAN bus.

That is, as shown in FIG. 1, the CAN system 11 includes an engine timing controller (ETC) 15, an electronic control unit (ECU) 17, and a transaxle control unit (TCU) 19 via a CAN bus 13. ), Each controller such as a liquid crystal display (LCD) 21 and a generator control unit (GCU) 23 is monitored and controlled.

The technical configuration of these CAN systems and their technical requirements for automotive applications are described in ISO 11898 (high speed applications) and ISO 11519-2 (low speed applications).

And in the message frame of a CAN system constructed according to the standard of CAN version 2.0A as shown in Fig. 2, each frame is composed of seven different bit fields.

The bit fields in the message frame are the Start of Frame (SOF) field, the Arbitration field, the Control field, the Data field, the Cyclic Redundancy Check (CRC) field, the Acknowledgment field (ACK), and the End of Field (EOF), respectively. of Frame) field. At this time, each field is assigned a number of bits according to a predetermined scheme. For example, the data to be exchanged between each controller and the CAN system is loaded in a data field having a size of 0 to 8 bytes, and 15 bits are allocated to the CRC field for cyclic redundancy check (CRC check).

Twelve bits are allocated to the arbitration field, of which 11 bits are identifier fields and 1 bit is an RTR bit. The 11-bit identifier field is used to indicate the processing priority of CAN message frames transmitted during CAN communication, and a unique identifier or identification number is assigned to each CAN data generated in each controller so as to determine the priority. .

Therefore, all 11 bits are used to indicate the priority of the CAN data, and the priority of the data loaded in the corresponding message frame can be determined only when all 11 bit patterns are interpreted.

However, the prior art has a problem that a programmer must define an identification number and prepare a data sheet in consideration of the priority of all CAN data.

In addition, when adding CAN data, an identification number must be additionally defined. In this case, there is a problem that a programmer must find CAN data from an existing data sheet and reset the CAN data by considering the priority of each CAN data again.

In other words, the programming process is very complicated not only in data management techniques.

In addition, when analyzing general CAN data, it is possible to interpret CAN data only by looking at the identifier field on the CAN bus and confirming which data is sent from which controller. There is a problem that becomes impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve the field structure of the CAN message frame in a vehicle, whereby each controller identifies a data transmission / reception position by referring only to the identifier field of the message frame. To provide a way to operate a message frame in a can system.

1 is a block diagram of a typical CAN system.

2 is a block diagram of a conventional CAN message frame applied to FIG.

Figure 3 is a flow chart of a message frame operating method of the can system according to an embodiment of the present invention.

4 is a block diagram of a CAN message frame according to the present invention;

5A is an exemplary CAN data priority definition of each controller in accordance with the present invention.

FIG. 5B is an exemplary diagram of priority definition for CAN data inside the ETC in FIG. 5A; FIG.

FIG. 5C is an exemplary diagram when an identifier field is configured based on the definitions of FIGS. 5A and 5B. FIG.

In order to achieve the above object, a method of operating a message frame of a can system according to the present invention comprises: splitting an identifier field of a CAN message frame into a plurality of partitioned fields to be transmitted through a CAN system, and then each partitioned field of the identifier field. Defining a priority for CAN data of each controller in a bit pattern according to the size of the controller; According to the defined CAN data priority, the identifier field is configured by loading priority information on CAN data in a receiver controller, a transmitter controller and a transmitter controller for each of the plurality of divided fields, and configuring the identifier field. And transmitting and receiving the message frame.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in Fig. 3, the identifier field is divided into three field areas to define the CAN data priority to be suitable for the divided field areas. The definition of CAN data priority should then be defined for every controller that exchanges data with the CAN system.

The split field area of the identifier field is a destination field, a source field and a rank field. In each of the divided fields, various kinds of information for determining the priority of CAN data are loaded (ST21 to ST22).

More specifically, as shown in FIG. 4, 11 bits constituting the identifier field in the CAN message frame are divided into three field areas. In this case, the division of the field area may be variously performed. Preferably, three bits are allocated to the destination field, four bits are allocated to the source field, and four bits are allocated to the rank field.

Each divided field area has a unique function. First, the destination field is for indicating a receiving controller to receive the frame, the source field is for indicating a controller for transmitting the frame, and the priority field is for CAN data priority inside the controller for transmitting the frame. It is to direct.

As shown in FIG. 5A, three bits are used to define priorities for CAN data of controllers such as ETC, ECU, MCU, TCU, BMS, LCD, and GCU. At this time, the number of bits available for priority definition should not exceed the number of bits of the split field area having the smallest size among the divided field areas.

More specifically, the priority of each controller is defined according to the 3-bit bit pattern. The controller begins to define the highest priority of the controller as the bit pattern of '001' and the lowest priority is the bit of '111'. A system is defined by patterns. If priority is defined through a bit pattern consisting of three bits, priority of up to eight (2 ³ = 8) controllers can be defined.

Then, for each controller for which priority is defined, priority for internal CAN data is defined. The reason for defining the priority of CAN data inside each controller is to assign different priority to each CAN data generated inside each controller, so that the data with high priority can be processed first (ST23). ).

For example, as shown in FIG. 5B, priority of CAN data inside a controller called ETC may be defined. That is, if there are four data in the ETC controller and each data is CAN_DATA1, CAN_DATA2, CAN_DATA3, and CAN_DATA4, the priority is defined using a bit pattern of four bits for each data.

That is, the bit pattern of '0001' has the highest priority and '1111' has the lowest priority, so that the priority can be defined by selecting an appropriate bit pattern between the most significant bit pattern and the least significant bit pattern.

However, when the number of data to define the priority is not large, it is preferable to define at a proper interval rather than to define a continuous bit pattern. In other words, if the rank of the CAN data is not used continuously, the unused bit pattern can be found at the proper position when the CAN data is added later, and used for defining the priority. This avoids the hassle of redefining all data priorities when adding CAN data.

The identifier field is configured based on the CAN data priority of each defined controller. The configuration of the identifier field is performed when generating a CAN message frame (ST24).

That is, the controller to transmit the message frame configures the identifier field according to the scheme described above, and the remaining fields in the message frame configure according to the standard message frame scheme and load CAN data.

More specifically, in the CAN message frame in order to transmit data on the transmitting side, the priority of the controller that will receive the frame is loaded in a destination field consisting of three bits, and the priority of the transmitting side of the CAN message frame. It loads the information on the source field consisting of four bits, and loads the information on the priority of the CAN data loaded in the frame into the priority field consisting of four bits.

For example, as shown in FIG. 5C, an identifier field indicating that a controller to receive and refer to data is an LCD, a controller to be transmitted is an ETC, and data to be transmitted is CAN_DATA1.

Meanwhile, the priority of the transmitting controller is defined as three bits, and the number of bits of the source field to which the priority of the controller is to be loaded is four. So the most significant one bit of the source field is not used.

In the case of FIG. 5C, the entire identifier field has a bit pattern of '11000010010', and when the bit pattern is expressed in hexadecimal, it is '0x612'. When interpreting the hexadecimal representation, the first digit '6' indicates the LCD controller, the second digit '1' indicates the ETC controller, and the third digit '2' indicates the ETC controller. It indicates internal CAN_DATA1.

When the transmitting side generates the CAN message frame, the transmitting side controller transmits the corresponding message frame through the CAN bus (ST25).

Message frames sent over the CAN bus are received by the controller indicated in the destination field. The controller receiving the message frame interprets the identifier field in the corresponding message frame, identifying the controller that transmitted the frame through the source field, and the priority of the CAN data inside the transmitting controller through the priority field. (ST26).

According to the present invention as described above, by improving the manner of defining the identifier field of the CAN message frame exchanged between each controller and the CAN system to define the priority of the controller to receive the frame, the controller to transmit and the data transmitted Each controller can identify the transmitting / receiving side of the frame by referring to the identifier field of the frame transmitted on the CAN bus, thereby making it easy to detect an error caused on the CAN bus.

And when an error occurs on the CAN bus in the future, it is easy to detect the error caused in the frame being transmitted, and the efficiency can be expected to be improved in terms of addition and management of CAN data.

In addition, in defining the CAN data priority within each controller, by using the available bit pattern discontinuously instead of continuously, the priority of the data when redefining the identification number according to the additional CAN data Can be easily defined using an unused bit pattern within the discontinuous section.

In addition, even if there is a large number of CAN data that needs to be defined, it can be defined step by step to suit the identifier field consisting of three partitioned fields. There is an effect that can increase the administrative convenience, such as / delete / change the priority.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Therefore, the above description does not limit the scope of the following claims.

Claims (5)

(a) After splitting the identifier field of the CAN message frame to be transmitted through the CAN system into a plurality of partition fields, the priority of the CAN data of each controller in a bit pattern according to the size of each partition field of the identifier field. Defining a; (b) constructing an identifier field by loading priority information on CAN data inside a receiving controller, a transmitting controller, and a transmitting controller for each of the plurality of divided fields according to the defined CAN data priority, and then configuring the identifier field And transmitting and receiving the message frame including the field. The method of claim 1, wherein the identifier field, A destination field for indicating a priority of a receiving controller connected to the CAN system; A source field for indicating a priority of a transmitting controller connected to the CAN system; It is composed of three divided fields including a priority field for indicating the priority of the internal CAN data of the transmitting controller connected to the CAN system, Of the total number of bits assigned to the identifier field, three bits are allocated to the destination field, four bits are assigned to the source field, remaining bits are allocated to the rank field, and the number of bits allocated to each split field is assigned. Method of operating a message frame of a can system, characterized by defining the priority of each CAN data using a configurable bit pattern. The method of claim 1, wherein step (a) comprises: (A1) defining priority of CAN data of each controller connected to the CAN system according to a bit pattern consisting of three bits; And (a2) defining a priority of each CAN data in the controller having a priority defined by the bit pattern of the three bits according to a bit pattern consisting of four bits. How to operate the message frame of the system. The method of claim 3, wherein step (a2) comprises: Unused bit patterns between bit patterns defining the priority of each CAN data by defining the priority by discontinuously using a part of the bit patterns configurable as 4 bits for each CAN data in the controller to be defined. Making it exist; And defining a priority of the added CAN data by using an unused bit pattern existing between the bit patterns defined for the respective CAN data. The method of claim 1, wherein step (b) comprises: Constructing an identifier field by loading information on CAN data priorities in a receiving controller, a transmitting controller, and a transmitting controller in a plurality of divided fields in the transmitting controller to transmit the CAN data; ; Generating, by the transmitting controller, a message frame including the configured identifier field and transmitting the same over the CAN bus of the CAN system; A receiving side controller indicated by a split field indicating a receiving side controller among the identifier fields on a message frame transmitted by the transmitting side controller receives the message frame, and the receiving side controller receives the identifier field on the received frame. And processing CAN data loaded on the message frame according to a priority defined by interpreting all of the message frames.