The PLC gives industry the power, speed, and flexibility of a computer. By replacing mechanical components with a PLC, the control of a process becomes faster, cheaper, and therefore, more efficient. The PLC is a better choice than relays or a standard computer for several reasons. These include:

• Less Space – A PLC requires much less space than a standard computers or a relay panel that could do the same job.
• Lower Cost – A PLC can cost as little as four or five relays, but is can replace hundreds of relays.
• Resistant to the Environment – A PLC’s casing is industrially hardened to withstand the harsh environment of a factory.
• Direct Interface – Standard computers require a complex and limited system to interface to real world components, while a PLC can be directly wired to these components.
• Easy Programming – PLCs most often use a programming language called ladder logic. This language is based on industrial standard symbology used in hard-wired relay systems.
• Flexibility – PLC programming can be changed much more quickly than hard wired relays and a PLC requires few (if any) component changes.