Run-time interpretation of STEP-NC: implementation and performance

Abstract

This paper describes an experiment in building and running two STEP-NC interpreters for milling operations: one using ISO 14649, the other using AP 238 of ISO 10303. Both use STEP part 21 exchange files as input and call low-level machine control functions. Both include tool path generators and have sufficient functionality to execute the first example program at the end of part 11 of ISO 14649. The objectives and results were: (1) to determine if ISO 14649 and AP 238 contain sufficient information to run a machining centre (yes); (2) to determine whether AP 238 faithfully remodels the information in ISO 14649 for the functionality that was implemented (yes); (3) to determine whether real-time interpretation of STEP-NC is feasible (yes); (4) to determine the burden on systems programmers to build a STEP-NC interpreter (heavy); (5) to determine how interpretation time varies with file size (linearly for both interpreters); and (6) to compare the speed with which the two formats can be interpreted. Using currently available software tools, ISO 14649 can be interpreted significantly faster, but both interpreters are so fast that interpretation time is negligible compared with running time.

Keywords:

• STEP-NC
• Machining operations
• Interpreter
• Functionality