An adaptable CNC system based on STEP-NC and function blocks

Abstract

Superior to G-code, STEP-NC is a new data model for computer numerical control (CNC). It provides rich information for CNC machine tools. This high-level information contains feature-based data. Unlike G-code that describes ‘how-to-do’, STEP-NC models ‘what-to-do’ at the task level in terms of features and ‘Workingsteps’. In the absence of a STEP-NC controller, there is a need for a system which can work with STEP-NC data and at the same time interface with the existing CNC machine tools. This paper describes such a system. This system acts like a ‘front-end’ for the current CNC controllers, giving these machine tools a ‘Plug-and-Play’ feature. The core of the system is the mapping mechanism which accepts STEP-NC data and translates it into the type of G-code that a specific controller can understand. The key to the mapping mechanism is the use of function block (IEC 61499) technology. This gives the system robustness and modularity.