| 摘要 |
The invention permits multiple secondary stations to be connected in a multipoint communication network to a single primary station utilizing point-to-point interfaces such as the standard RS-232 or V.35 which do not ordinarily support multipoint connections. A primary station is connected to one secondary station or modem through a point-to-point interface utilizing either a straight through or cross over cable depending upon whether a modem is included. Data goes through the secondary station or modem to a second interface which is connected to a different secondary station or modem. This type of connection is referred to as a daisy chain. Data is not buffered in the secondary stations but is transmitted directly through each station. Each station monitors the daisy chain signals for clocking, status and identification of data for itself. Since there is no buffering, only a single set of clocking can be used in the chain. The invention allows the individual station to choose the method of clocking to be used throughout the chain without loss of synchronization between data and clocking. When modems are installed in the chain, they provide clocking and status signals. When no modems are installed, the primary station or one secondary station must provide the clocking and status signals. If the primary station fails to provide clocking, the secondary station at the end of the daisy chain provides the clocking and wraps back status signals using a simple logic network. The chain is self-adjusting to changes in topology and to additions and deletions of modems and/or secondary stations. |
