PLC programmable controller, is the most common type of ladder diagram editor, PLC software comes with encryption, after downloading the program make others cannot upload to read ladder diagram, write your own functions so as to achieve the protection of intellectual property rights, but it also bring inconvenience to the follow-up machine maintenance, some can't find the manufacturer, after the equipment sold or second-hand equipment is broken, if not PLC ladder diagram is hard to repair, so want to read PLC ladder diagram have to crack the password, so we developed the PLC password cracking software for all to use, all kinds of PLC programming software to download this tutorial http://www.ljcplc.com/