CNC and PLC: are they one and the same for machine tools?

The traditionally accepted way of designing a computerized numerical controller (CNC) is to split the architecture into three entities: a programmable logical controller (PLC), a black box that could be called a CNC director (CNCD), and a composite entity containing the CNC axes controllers and which could be simply expressed as the axes entity. The drawbacks involved in this architecture are described and a new architecture for the whole CNC is presented. The advantages implied by the new architecture are considered. The comparison of the proposed architecture with a traditional PLC architecture led to the conclusion that CNC evolution is based on the PLC