Apparatus and method for extracting common command information from PLC ladder information

A method of extracting common command information from programmable logic controller (PLC) ladder information, the method comprising:

• extracting control logic information from XML information converted from PLC ladder information;
• and
• converting the extracted control logic information into common command information,
• wherein the extracting of the control logic information includes extracting, from the XML information, the control logic information in the form of a block obtained by grouping units that respectively represent contacts and lines constituting the PLC ladder information according to an AND condition and an OR condition,
• wherein the extracting of the control logic information includes generating basic unit table information on units including a contact constituting the PLC ladder information, updating the basic unit table information through setting of each of child units corresponding to a lower tree structure of each unit included in the basic unit table information by using the XML information, updating the basic unit table information through setting of parent units corresponding to the child units by using the XML information, and according to a relationship between the child units and the parent units, generating a block in which each unit is grouped according to the AND condition and the OR condition in the unit table information, and extracting the control logic information by repeating the generation of a block until one final block is generated.