PC-DMIS in Offline mode enables you to prepare and debug measurement routines without using a CMM. The ability to program offline has become increasingly important over the last several years. Users of CMMs have become more aware that, to fully realize their investments in CMMs, their equipment must be used to measure parts and not write routines to measure parts.
CMM manufacturers' first attempts at adding offline programming capabilities involved cumbersome and specialized text editors. These products, although of limited use, spurred user interest in offline programming. Driven by this interest, several CAD vendors developed products that allowed users to use CAD models to generate measurement routines.
Although these products were vastly superior to text editors, they had a major cost disadvantage. Since each CMM vendor has their own specific measurement language or languages that were constantly changing or being replaced, the expense of developing and maintaining these products put them out of the reach of all but a few well-financed users.
This situation brought about the development of the DMIS specification, which is a generic CMM language. DMIS allowed CAD vendors to develop measurement routine programming packages that were targeted toward a single language instead of many, which greatly reduced their costs. These savings were passed on to their customers, and offline measurement routine programming became a viable option for a large group of CMM users. However, there was still one problem: What about CMM users whose CAD vendors did not support, and did not plan to support, offline measurement routine programming?
Although many mainframe CAD vendors, driven by major customers, have introduced DMIS extensions to their products, PC-based CAD vendors with their diverse customer bases have shown little interest in this area. Many CMM users, particularly small shops, use PC-based CAD systems exclusively. PC-DMIS brings offline programming capabilities to this group.
With PC-DMIS, programmers who use standard IGES models, which virtually every CAD vendor supports, can generate measurement routines on an inexpensive PC or PC clone without going near a CMM. These measurement routines can then drive any CMM that either runs PC-DMIS or supports the DMIS specification.
The techniques for programming offline are much the same as those used for programming in Online mode. However, as might be expected, the methods used to qualify probes, take measurements, and debug routines differ from those in Online mode. This appendix describes PC-DMIS programming techniques in Offline mode.
The main topics in this chapter include: