THE use of function blocks for programming of programmable logic controllers (PLCs) is gaining wider acceptance. Rather than the classic “contact and coil” representation of ladder diagram or relay ...

Some control applications are too small or simple to use even the smallest PLC, but still need more flexibility than a simple relay. That's why engineers at Schneider Electric, Palatine, Ill.

Over the years, control relays of various types have been used by the hundreds — even thousands — to control nearly every function in commercial and industrial processes. Today, many of those ...