| 摘要 |
A modular communication network includes a small number of different exchange units including a network controller exchange unit, line master exchange units, line exchange units and terminal exchange units. The network employs a communication format in which a single message for a single terminal unit includes at least one standard length data block, each data block including data information being communicated and control information indicating an address of an associated terminal unit, a sequence code indicating the sequential position of the block among other blocks of a message and an error checking code permitting detection of an error in a block of communicated data, the line master exchange unit device 60 retransmitting a message upon the occurrence of an indication of an error in transmitting a message to a terminal unit; each addressable terminal node device receives blocks of data containing an address thereof and assembles received blocks of data into messages in the sequential order indicated by the sequence code, each sending an acknowledgement message through the communication medium to the line master exchange unit device 60 upon receipt of a complete error free message, and each communicating messages received from the communicating system to a terminal device connected thereto.
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