How does a PLC (Programmable Logic Controller) compare to an embedded system?

A PLC (Programmable Logic Controller) is one of the main devices used in industry to implement: monitoring, logic, control, or other events/functions impossible (or to complicated) to be done mechanically. With respect to embedded systems, a PLC is in fact an embedded system running a program to provide the various functions PLCs typically provide. Depending on the particular model of PLC, software running on the embedded system likely includes the following functions: Interpret a high level command language such as ladder logic and carry out the meaning of those commands. Provide an environment to facilitate the programming in a high level language such as ladder logic...