| 摘要 |
PURPOSE: A method for changing a reference clock and a master clock by the request of an operator in a clock distributing unit of a network synchronous device is provided to supply a reference signal from a clock distributing unit(reference clock distributing unit) requested by an operator to a clock generating unit and supply a system clock from a clock distributing unit(master clock distributing unit) requested by the operator to an optical link unit of a switch. CONSTITUTION: If a clock distributing unit to be changed is a reference clock distributing unit, it is confirmed whether the reference clock distributing unit of the clock distributing unit deviates from a reference range(ST1). It is confirmed whether the clock distributing unit requested by an operator is abnormal(ST2). If the clock distributing unit requested by the operator is normal, it is confirmed whether the reference clock distributing unit to be changed is identical to a current reference clock distributing unit(ST3). If the reference clock distributing unit to be changed is not identical to the current reference clock distributing unit, values of reference clock output registers of 3 clock distributing units are changed from '1' to '0' so that one clock distributing unit is set up as the reference clock distributing unit(ST5). The values of the reference clock output registers of the other 2 clock distributing units except for the clock distributing unit to be changed are changed from '0' to '1'(ST6).
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