Method and device for serial data transmission over a bidirectional data channel

A device for serial data transmission between a position-measuring device and subsequent electronics over a bidirectional data channel, the device comprising:

• the position-measuring device and the subsequent electronics each including an interface configured to generate data frames from at least one of data and instructions to be transmitted that are deliverable to the interfaces of the position-measuring device and the subsequent electronics from source components, the interfaces being configured to encode the data frames in accordance with a data transmission code and output the encoded data frames to the data channel, the interfaces being configured to initiate a data transmission in each case by a transmitter end with a start sequence whose encoding scheme at least partially differs from an encoding scheme of a remainder of the data frames and the interfaces being configured to detect in each case at a receiver end, after a reversal of data direction, a beginning of the data transmission by detection of the start sequence,
• wherein the interfaces each include a communicator, an outputter and a reader, and wherein the communicators are each configured to:
• generate partial data packets from the at least one of data and instructions;
• output the partial data packets to a respective one of the outputters;
• and
• receive and process the partial data packets from a respective one of the readers so that the at least one of data and instructions contained in the partial data packets are deliverable to addressed target components,
• wherein the readers each include a comparator and a decoder, the comparators being configured to compare a data stream of the partial data packets arriving over the data channel with the start sequence and to signal a positive comparison result to the decoder, and the decoders respective to the readers being configured to decode the partial data packets and to deliver the decoded partial data packets to a respective one of the communicators,
• wherein the readers each include a synchronizer configured to receive the data stream arriving over the data channel and to synchronize the data stream with a clock signal, and
• wherein the encoding scheme of the remainder of the data frames is a Manchester encoding scheme in which a data stream for the data transmission contains a sequence of short symbols and long symbols, and the readers include a symbol discriminator configured to receive the synchronized data stream from a respective one of the synchronizers, to determine the sequence of short symbols and long symbols in the synchronized stream and to transmit only the determined sequence to a respective one of the decoders for decoding.