# Implementation by High-Level Interface (HLI)

A memory area is created as shared memory which both the CNC and the PLC can access in order to implement data exchange between CNC and PLC. This memory area is referred to as High-Level Interface (HLI).

In order to allow this data access, the relevant views from CNC and PLC onto the memory area must be identical. Data consistency is ensured by means of suitable data exchange mechanisms.

A library containing the structure of the HLI in structured text is provided for simple programming at the PLC end in IEC1131-3. This library is valid in each case for the current HLI format and the current status of the CNC and may change if a version update is implemented. Accordingly, the PLC must be recompiled and loaded if there is new library or if a new CNC is used.