Programmable Controllers: State-of-the-Art-Systems

Abstract

Because of the very large number of quality manufacturers of programmable controllers (PCs) in the United States, Europe, and Japan, most of whom do not offer a single product but rather a family of related products designed to satisfy the requirements of a large range of applications, selecting a system best suited to a given application has become increasingly difficult during the past several years. Consequently, efforts have been made to construct tabular comparisons of the capabilities and features of PCs. In one tabular system¹, the following criteria are listed:

• Total system I/O

• Maximum discrete I/O

• Maximum analog I/O

• Relay ladder logic

• High-level language

• PID capabilities

• Motion control

• Documentation

• PC data highway

• Type of interface

• Scan rate

• Type and size of memory