During the last ten to fifteen years, many different languages have been used to write programs for industrial control applications and Programmable Logic Controllers (PLCs). This lack of standardization costs technicians, maintenance personnel, system designers, and plant managers both time and money. To correct this problem, a working group within the International Electro-technical Commission (IEC) was set up to look at the overall design of programmable logic controllers, including hardware design, installation, testing, documentation, programming, and communications. The IEC developed the IEC61131 standard to address all aspects of PLC design and IEC61131-3 is becoming the standard PLC programming language worldwide. IEC61131-3 covers the programmable languages Function Block Diagram (FBD), Ladder Diagram (LD), Sequential Function Chart (SFC), Structured Text (ST), and Instruction List (IL).