Custom Design of an Analogue Input Digital Output Interface Card for Small Size PLCs

This paper describes the design and implementation of an interface card (IC) with analogue input and digital output, designed for use with small size PLCs, which do not support interface features. The absence of generic I/O interface modules due to the differences in PLCs design and software, validates the importance of such work. The IC costs about one third of an analogue I/O dedicated proprietary module. The IC was utilized in a closed loop temperature control system. The results of the work are satisfactory.