Profinet is an open, real-time industrial Ethernet standard in automation industry, which is flexible, efficient, and high-performance. Profinet Ethernet was born a long time ago. As an open standard, it has been well applied in Germany, where it was born. Moreover, there are typical applications in China's automobile and tobacco industries.
1. Profinet communication standard
Profinet Ethernet can provide an open and consistent connection for the office and the automation field. Profinet scheme covers all running stages of distributed automation system, which mainly includes the following aspects:
(1) Open object model (structural model) of highly decentralized automation system.
(2) Open and object-oriented runtime communication scheme based on Ethernet and ethernet transceiver (communication relationship between functional units).
(3) Engineering design scheme independent of manufacturer (application development).
Profinet scheme can be described simply and clearly by an equation: Profinet = Profibus + open and consistent communication of Ethernet with PROFIBUS and IT standard.
2. Realization of Profinet communication function
The realization of the communication function of Profinet equipment is based on the traditional Ethernet communication mechanism (such as TCP or UDP) and the adoption of RPC and DCOM mechanisms for augment. DCOM can be regarded as an extension of COM technology for RPC-based distributed applications. It can be applied to applications with strict real-time requirements by adopting optimized real-time communication mechanism.
Profinet devices are imaged in the form of DCOM objects during operation. The communication of DCOM objects is ensured through the object protocol mechanism. COM objects appear as PDUs on the communication bus in the form defined by the DCOM protocol. Through DCOM wiring protocol, DCOM defines the identification of objects and methods with relevant interfaces and parameters, so that standardized DCOM packets can be transmitted on the communication bus. Profinet Ethernet can also use the integrated OPC (OLE for Process Control) interface technology for higher-level communication.