A fully accepted standard for motion control over DeviceNet does not yet exist, however, so many users, who choose DeviceNet, build custom motion extensions. A brief look at a few types of motion applications reveals how their controls might be distributed. While not an all-inclusive sampling, these applications show a fairly broad spectrum of industries and products using motion control. Since sub-millisecond synchronization is generally not required, the network reduces the cost of wiring across relatively large distances. These systems tend to be highly engineered machines in which size and performance are the primary factors.
Space is at a premium with sizes ranging from around a cubic foot to closet-sized.
With this kind of application, a serious question arises whether networking is warranted, because distributing electronics throughout the machine often causes more servicing problems than it solves. Cell controller applications include batch-oriented cell controllers, semiconductor cluster tools, some general automation, and some medical systems. This processing system is made up of two or more relatively autonomous, intelligent processing units. In this application, the network performs relatively little real-time synchronization, while it handles fairly large amounts of data. Ethernet or Foundation fieldbus would be good choices.