Abstract:

A tobacco logistics company uses Siemens S7-300, S7-400 series PLC control system to complete the daily warehousing and sorting task. Once the system has a fault of electrical interference，system design, component selection, installation and manufacturing process and so on, it needs to be repaired as soon as possible so that the system to work again. For the PLC control system fault and fault causes and effects，measures were taken to limit the expansion of the fault, and the fault to be eliminated promptly. Storage and sorting PLC control system used in tobacco logistics companies are huge，good inspection and maintenance work must be done to ensure safe and stable operation of the system. Good maintenance of the system can be in time to prevent the occurrence of system failure. When the system fails，the correct method is used to repair the fault. After the failure，the fault was summarized and continuous technological innovation was done so as to prevent similar failures.

Key words: PLC control system, fault;, maintenance