Industrial automation is widely used in industrial production of automatic control, automatic adjustment device, to replace manual control machine and machine system for processing production trend. Under the condition of industrial production automation, people only indirectly take care of and supervise the production of machines. Industrial automation, according to its development stage can be divided into :(1) semi-automation. That is, part of the automatic control and automatic devices, and the other part of the manual operation of the machine for production. (2) Full automation. Point to the whole working procedure in the production process, including on material, next material, loading and unloading, do not need the person to undertake production operation directly (the person is only indirectly watch and supervise the machine to run), and by the machine continuously, repeatedly automatically produce a or a batch of products.