求翻译：On LCU15A ( LCU15B) maintenance can be divided into two parts : LCU local cabinet overhaul and remote I / O maintenance. Because the remote I / O according to a string arrangement, so that the remote I / O repair with string switch maintenance. Local cabinet overhaul includes controller, PLC of the corresponding period and cabinet. The fastening work, controller for maintenance, to be on the main controller to switch, switching period (about 1 ~ 2 hours, there is a certain risk, because the spare controller not long run, may start without success), II I (left left ) switch station equipment state can not be sent ; while the earlier PLC overhaul will affect the switching of the synchronization operation.是什么意思？

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