| 摘要 |
PURPOSE:To make it possible to select a definite and high-speed stand-by system data link by giving a difference in fault recognition time between controllers of two offices when a fault occurs in a stand-by data link. CONSTITUTION:For example, when a link control system in data-link-''0'' synchronous mode and control information is transferred between both offices, the occurrence of a fault in the link results in that data link supervisory unit SUP detects CRC check errors respectively to set the data-link-''0'' synchronous mode. During the following independent fault recognition time, both offices detect CRC check errors continuously to set the data-link-''I'' selection mode through data link switching circuit LCT. Here, providing a difference in time much greater than the fault recognition time between opposing offices A and B prevents what is called a race of link switching, so that a stand-by data link can be selected rapidly. |
