Method and device for checking the correct functioning of a serial data transmission

Patent metadata

Field	Value
Publication number	US-10146725-B2
Application number	US-201214342282-A
Country	US
Kind code	B2
Filing date	Aug 24, 2012
Priority date	Aug 29, 2011
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A method is described for checking the correct functioning of a serial data transmission in a bus system having at least two bus users. The bus users are connected to the bus via a bus connection unit and exchange messages via the bus. The sending access to the bus for each message is granted to a bus user via the arbitration process according to CAN standard ISO 11898-1, this bus user becoming the sender for this message. The messages have a logic structure according to the CAN standard, i.e., are composed of a start of frame bit, arbitration field, control field, data field, CRC field, acknowledge field, and end of frame field. The correct functioning of the data transmission is checked during the transmission by comparing a transmission signal, sent to the bus connection unit, to the reception signal (CAN_RX) received by the bus connection unit. The method is characterized in that a transmission signal (CAN_TX_DEL), which is delayed by a delay time (T_DELAY) compared to the transmission signal (CAN_TX), is held in the sender, and the undelayed transmission signal (CAN_TX) or the delayed transmission signal (CAN_TX_DEL) is used for checking the correct functioning of the data transmission, as a function of a switchover.

First claim

What is claimed is:

1. A method for checking a correct functioning of a serial data transmission in a bus system having at least two bus users, comprising:
connecting the bus users to a bus via a bus connection unit;
exchanging messages via the bus;
granting a sending access to the bus for each message to a bus user via an arbitration process according to CAN standard ISO 11898-1, the bus user becoming a sender for the message, each message having a logic structure according to the CAN standard, the logic structure including a start of frame bit, arbitration field, control field, data field, CRC field, acknowledge field, and end of frame field; and
checking, by the sender, a correct functioning of the data transmission during a transmission to send the message by comparing one of a transmission signal sent to the bus connection unit for transmission on the bus and a delayed transmission signal to a reception signal received by the bus connection unit from the bus, wherein the delayed transmission signal is delayed compared to the transmission signal by a delay time and held in the sender, the one of the transmission signal and the delayed transmission signal being used for checking the correct functioning of the data transmission as a function of a switchover between using the transmission signal and using the delayed transmission signal, the switchover occurring during the transmission to send the message.

2. The method as recited in claim 1 , wherein the delay time (T_DELAY) is one of predefined and predefinable.

3. The method as recited in claim 1 , wherein the delay time is a function of an ascertainment of one of a time delay and an averaged time delay.

4. The method as recited in claim 3 , wherein the averaged time delay is ascertained from multiple messages sent in succession by mean value formation from multiple measured values, ascertained in succession, of the time delay.

5. The method as recited in claim 4 , wherein the measured values which greatly deviate from the last determined mean value are sorted out during a formation of the mean value.

6. The method as recited in claim 5 , wherein one of a threshold value for a difference and a limiting value for a ratio of an instantaneously present measured value and the last determined mean value above which the deviation from, or the ratio to, the mean value for which the absolute value has been classified as excessively large is settable.

7. The method as recited in claim 6 , wherein the measured values of the time delay are managed in a list which is initialized by a suitable process upon system start-up, so that no invalid values are used in the formation of the mean value.

8. The method as recited in claim 7 , wherein the ascertainment of the individual time delay takes place after the sending access has been granted to a bus user.

9. The method as recited in claim 8 , wherein the ascertainment of the individual time delay includes a recognition in each case of one of at least one signal change and a signal edge in the transmission signal and in the reception signal.

10. The method as recited in claim 9 , further comprising determining a comparison point in time for the checking of the correct functioning of the data transmission as a function of the ascertained time delay.

11. The method as recited in claim 10 , wherein the comparison point in time for the checking of the correct functioning of the data transmission is determined as a sum of the ascertained time delay and one of a predefined and a predefinable percentage of a bit length.

12. The method as recited in claim 1 , wherein the transmission signal is used for the checking during the arbitration process, and the delayed transmission signal is used for the checking for at least a portion of the transmission to send the message after the arbitration process.

13. The method as recited in claim 1 , wherein a comparator carries out the comparing of the one of the transmission signal and the delayed transmission signal to the reception signal at a comparison point in time.

14. The method as recited in claim 1 , further comprising, when an identifier is present in the message, performing a switchover to using a bit length for at least a portion of the message having a value that is shorter than a bit length used prior to the presence of the identifier.

15. A method for checking a correct functioning of a serial data transmission in a bus system having at least two bus users, comprising:
connecting the bus users to a bus via a bus connection unit;
exchanging messages via the bus;
granting a sending access to the bus for each message to a bus user via an arbitration process according to CAN standard ISO 11898-1, the bus user becoming a sender for the message, each message having a logic structure according to the CAN standard, the logic structure including a start of frame bit, arbitration field, control field, data field, CRC field, acknowledge field, and end of frame field; and
checking, by the sender, a correct functioning of the data transmission during a transmission to send the message by comparing one of a transmission signal sent to the bus connection unit for transmission on the bus and a delayed transmission signal to a reception signal received by the bus connection unit from the bus, wherein the delayed transmission signal is delayed compared to the transmission signal by a delay time and held in the sender, the one of the transmission signal and the delayed transmission signal being used for checking the correct functioning of the data transmission as a function of a switchover between using the transmission signal and using the delayed transmission signal, wherein the switchover takes place in response to reaching and evaluating one of a predefined and predefinable bit within the message.

16. The method as recited in claim 15 , wherein the messages in which the switchover takes place are identified by a suitable identifier.

17. The method as recited in claim 16 , wherein when a first identifier is present, the control field of the messages, in a deviation from the CAN standard, contains more than six bits.

18. The method as recited in claim 17 , wherein the first identifier for messages having standard addressing takes place via a recessive second bit in the control field, and for messages having extended addressing, takes place via at least one of a recessive first bit and a second bit in the control field.

19. The method as recited in claim 18 , wherein when the first identifier is present, a recessive bit of the first identifier is followed by at least one dominant bit in all data messages.

20. The method as recited in claim 19 , wherein when the first identifier is present, an edge between the recessive bit of the first identifier and the at least one subsequent dominant bit is used for ascertaining the time delay between the transmission signal and the reception signal.

21. The method as recited in claim 20 , wherein when the first identifier is present, the data field of the messages, in a departure from CAN standard ISO 11898-1, may contain more than eight bytes, for establishing the size of the data field, the values of the four bits of the data length code being interpreted differently from CAN standard ISO 11898-1, at least in part.

22. The method as recited in claim 21 , wherein when a second identifier is present, a bit length for at least one of a predefined and a predefinable area within the message assumes a value that is shorter than a bit leng

Assignees

• Hartwich Florian
• Bailer Franz
• Horst Christian
• Mutter Arthur
• Bosch Gmbh Robert

Inventors

• Hartwich Florian
• Bailer Franz
• Horst Christian
• Mutter Arthur

Classifications

• H04L2012/40215

  Controller Area Network CAN · CPC title

• H04L12/4135

  using bit-wise arbitration · CPC title

• H04L12/4013

  Management of data rate on the bus (systems modifying transmission characteristics according to link quality H04L1/0001) · CPC title

• G06F13/362

  with centralised access control · CPC title

• G06F13/4282 Primary

  on a serial bus, e.g. I2C bus, SPI bus (on daisy chain buses G06F13/4247) · CPC title