| 摘要 |
PURPOSE:To provide the data communication system which always performs FIFO operation and is capable of high-speed processing and has a protocol of high quality. CONSTITUTION:In the data communication system, overhead bytes of the section layer and the line layer are used for transmission of common control data on a back plane bus conforming to American telecommunication protocol SONET. For example, in a data unit consisting of an STS-1 frame, a preliminarily defined number of time slots are assigned to a synchronizing payload envelope SPE for confirmation of data transfer through synchronous busses 501, 502, and 503 having request confirmation lines 531, 532, and 533. Each data unit is provided with a queue counter and a count-down counter which monitor the number of all pending packets and the number of packets preceding a queue transferred from the unit itself respectively. This data communication system is realized on the PCM bus using transmission/reception circuits.
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