Frame-structured bus system for transmitting both synchronous and asynchronous data over a star-coupled local operation network
First Claim
1. A local operation network having a number of stations each connected by a bus line to a central star coupler, whereineach message sent out by a respective sending station is transmitted via the central star coupler to all stations of the local operation network,at least one of said stations is a master station including a frame clock generator for generating a master frame clock in the form of a sequence of data frames of a defined bit length, each said data frame including a start module followed by an isochronous frame module having a variable first bit length, an end module preceded by an asynchronous frame module having a variable second bit length, and a division module between the isochronous frame module and the asynchronous frame module,said master frame clock is transmitted from said master station to the central star coupler,in the central star coupler, the time sequence of the data frames of the master frame clock defines a reference frame clock governing the signal processing of the stations of the local operation network,each of the stations of the local operation network determines a respective propagation delay from that station to the central star coupler and uses that propagation delay to generate an individual frame transmit clock, such thateach message transmitted by said respective sending station arrives at the central star coupler at the latter at a respective assigned instant of the reference frame clock at which that message must be incorporated into a current data frame then present in the central star coupler, andthe current data frame containing messages from a plurality of the sending stations is sent to all stations,each of a plurality of asynchronous submodules is assigned to a respective bus station,isochronous data is transmitted at the beginning of each frame during said isochronous frame module,the plurality of asynchronous submodules are transmitted at the end of each frame within said asynchronous frame module, andsaid division module is transmitted by said master station at different respective locations within two successive frames, thereby dynamically establishing said variable first and second bit lengths for each of the frames.
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Abstract
A frame-structured bus system, particularly for a local operation network for automotive applications, is disclosed in which a plurality of bus stations share a data bus, and in which one of the bus stations generates a sequence of data frames of constant bit length. Each data frame includes an isochronous frame module and an asynchronous frame module, and the division of each data frame into the isochronous and asynchronous frame modules is dynamically variable. The message transmitted by a station is passed through a central star coupler to all stations. A frame clock is generated by a frame clock generator and sent to the central star coupler, with the time sequence of the data frames of the frame clock defining a reference frame clock, and the other stations of the local operation network determining an individual frame transmit clock, such that the respective message transmitted by a particular station, taking into account the propagation delay to the central star coupler, arrives at the central star coupler at that instant relative to the reference frame clock at which this message has to be inserted into the data frame present in the central star coupler.
32 Citations
20 Claims
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1. A local operation network having a number of stations each connected by a bus line to a central star coupler, wherein
each message sent out by a respective sending station is transmitted via the central star coupler to all stations of the local operation network, at least one of said stations is a master station including a frame clock generator for generating a master frame clock in the form of a sequence of data frames of a defined bit length, each said data frame including a start module followed by an isochronous frame module having a variable first bit length, an end module preceded by an asynchronous frame module having a variable second bit length, and a division module between the isochronous frame module and the asynchronous frame module, said master frame clock is transmitted from said master station to the central star coupler, in the central star coupler, the time sequence of the data frames of the master frame clock defines a reference frame clock governing the signal processing of the stations of the local operation network, each of the stations of the local operation network determines a respective propagation delay from that station to the central star coupler and uses that propagation delay to generate an individual frame transmit clock, such that each message transmitted by said respective sending station arrives at the central star coupler at the latter at a respective assigned instant of the reference frame clock at which that message must be incorporated into a current data frame then present in the central star coupler, and the current data frame containing messages from a plurality of the sending stations is sent to all stations, each of a plurality of asynchronous submodules is assigned to a respective bus station, isochronous data is transmitted at the beginning of each frame during said isochronous frame module, the plurality of asynchronous submodules are transmitted at the end of each frame within said asynchronous frame module, and said division module is transmitted by said master station at different respective locations within two successive frames, thereby dynamically establishing said variable first and second bit lengths for each of the frames.
Specification