| 摘要 |
An automatic communications switching circuit is used to couple a primary terminal, an alternate terminal, a cluster of secondary terminals and a host system to enable communication and data transfer among the terminals and host system. The primary terminal normally handles data transfer and communication for the cluster of secondary terminals when the switching circuit is in the first state. A lack of polling by the primary terminal (which is an indication of inoperativeness of the primary terminal) is sensed by the alternate terminal which then starts the polling process. The polling by the alternate terminal is sensed by the switching circuit which is then switched to a second state in which the alternate terminal functions as the "primary" terminal.
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