Introduction

Extensive datasets are exchanged between CNC and PLC. These datasets comprise the following for instance

• Commands from the NC program of the CNC to the PLC (e.g. technology commands, such as M, S, T and H commands etc.).
• Acknowledgements of the technology commands by the PLC.
• Display data of the CNC (e.g. current axis positions, current and programmed tool path feedrate etc.).
• Jobs of the PLC to the CNC (e.g. mode switchover, set feed hold etc.).
• Jobs of the GUI to the CNC which can be verified and, if applicable denied by the PLC (e.g. mode switchover, set feed hold etc.).

The interface between CNC and PLC is outlined in the following general diagram.

Fig.1: Figure 0.1: CNC-PLC interface

This documentation describes the structure of this interface between CNC and PLC referred to below as High-Level Interface (HLI for short).

In this instance, High-Level Interface refers to the structuring of the interface with complex data structures and handshake variables. This is considered unlike a data interface at a low level of abstraction (Low-Level Interface).