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This paper presents an overview of PROFInet™, a high-level network for industrial automation applications. Built on standard DCOM and RPC technologies, PROFInet uses traditional Ethernet hardware and software to define a network that structures the task of configuring, accessing and controlling industrial automation devices. PROFInet is based on the object interface structure defined by DCOM (Distributed Component Object Model) which if you are familiar with the history of Microsoft inter-process communications is a descendant of DDE, OLE and Active X.
PROFInet views a system as composed of “Technological Components”. These components act independently and coordinate their activities to form an integrated system. DCOM is a good choice for such a system. It is an object oriented mechanism which structures how a Client (data requester) can locate, request and transfer data from a Server (data source). Building on the DCOM model PROFInet strives to provide a seamless integrated system from the sensor-actuator network to the controller and enterprise networks.
PROFInet is much more than Profibus on Ethernet. In fact, the name is very confusing. PROFInet has little or nothing in common with Profibus. Profibus is a data oriented mechanism for transferring I/O from device to device over a cable at a maximum speed of 12Meg baud. Profibus data exchange is mainly cyclic with devices having a prior understanding of the data structure and meaning. In PROFInet data can be located, information about its structure can be obtained and data can be exchanged on event triggers, cyclic schedules or other mechanisms. PROFInet operates on Ethernet at 10 to 100 megabaud speeds.
PROFInet uses more traditional Information Technology (IT) concepts and software than all of the other common networks for Industrial Ethernet applications. This has both advantages and disadvantages that will be apparent as the concepts in this paper are developed. |
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