Most textbooks related to programmable controllers start with the basics of
ladder logic, Boolean algebra, contacts, coils and all the other aspects of learning to
program PLCs. However, once they get more deeply into the subject, they generally
narrow the field of view to one particular manufacturer's unit (usually one of the more
popular brands and models), and concentrate on programming that device with it's
capabilities and peculiarities. This is worthwhile if the desire is to learn to program that
unit. However, after finishing the PLC course, the student will most likely be employed
in a position designing, programming, and maintaining systems using PLCs of another
brand or model, or even more likely, many machines with many different brands and
models of PLC. It seems to the authors that it would be more advantageous to
approach the study of PLCs using a general language that provides a thorough
knowledge of programming concepts that can be adapted to all controllers. This
language would be based on a collection of different manufacturer types with generally
the same programming technique and capability. Although it would be impossible to
teach one programming language and technique that would be applicable to each and
every programmable controller on the market, the student can be given a thorough
insight into programming methods with this general approach which will allow him or her
to easily adapt to any PLC encountered.