Device and method for global time information in event-controlled bus communication

摘要

In a method for exchanging data in messages between users of a CAN bus system, the users have their own time bases; a first user functioning as timer transmits a reference message having a specifiable identifier via the bus, which includes a first time information with regard to the time base of the first user; the at least second user, using its time base forms its own second time information as a function of the first time information of the first user in such a way that, from the deviation of the first and the second time information a correction value is ascertained, so that from the first time information of the first user as the timer, the global time for the bus system is yielded.

主权项

1. A system for exchanging data in messages using a CAN bus system, comprising:
a plurality of users, wherein each of the users has a respective local time base, and wherein each of the users represents a node; wherein a first user among the plurality of users functions as a system timer, the first user transmitting a reference message having a specified identifier via the bus, the reference message including a first time information with regard to a first local time base of the first user; wherein a second user among the plurality of users uses a second local time base associated with the second user to form the second user's own second time information as a function of the first time information of the first user so that a correction value is determined based on a deviation between the first time information and the second time information, so that from the first time information of the first user as the system timer, a global time for the bus system is yielded; wherein the reference message is repeatedly transmitted without a fixed time reference and exchange of messages between the users of the CAN bus system takes place in an event-controlled manner, the exchange of messages complying with the arbitration method according to the CAN standard; wherein the global time is generated in each of the nodes from its respective local time base and a respective local offset, and wherein the respective local offset is a difference between a local time at a point of transmission of a reference message and the global time transmitted in the reference message; and wherein, each user has one of a storage area or a register for configuration of a media access control method in each user, and wherein upon entering a specified value in said one of the storage area or the register, the exchange of messages between the users of the CAN bus system is able to be switched over to a time-controlled operation according to the TTCAN extension of the CAN standard.