Modicon M251 Plc Page 18 Communication bus

18 Presentation Modicon M251 logic controllers Industrial Ethernet network General Industrial Ethernet is the term used to refer to industrial communication protocols using Ethernet standard physical layers such as: v EtherNet/IP v Modbus TCP v TCP and UDP On an Ethernet Industrial network, it is possible to connect: v industrial products (industrial communication protocols) such as controllers, variable speed drives, robots, etc. v products using TCP/UDP-based proprietary protocols In addition, it is possible to use different Ethernet Industrial protocols on the same network simultaneously. The EtherNet/IP protocol EtherNet/IP is an industrial communication protocol based on CIP (Common Industrial Protocol), owned and managed by the ODVA, an independent standards organization (www.odva.org). EtherNet/IP is the result of implementing CIP protocol on standard Ethernet. EtherNet/IP operates on the same device and the same infrastructure as Modbus TCP, and both protocols can be activated simultaneously on the network at any time. EtherNet/IP is a robust protocol for use with sophisticated devices such as cameras, robots, etc. Advanced services and outstanding performance EtherNet/IP is object-oriented. In each EtherNet/IP device, the data is arranged as objects and each device can be associated with several types of object depending on its intended use. Integration of devices is made easy thanks to predefined and standard objects. The EtherNet/IP protocol uses an Originator/Target architecture for data exchanges. The Modbus TCP protocol Modbus has been the industry communication standard since 1979. During the internet revolution, Modbus was combined with Ethernet to form Modbus TCP, a completely open Ethernet protocol. Modbus TCP, simple and open The Modbus application layer is simple and universally familiar with its 9 million installed connections. v Thousands of manufacturers have already implemented this protocol. Many have already developed a Modbus TCP connection and numerous products are currently available. v The simplicity of Modbus TCP enables any fieldbus device, such as an I/O module, to communicate on Ethernet without the need for a powerful microprocessor or a lot of internal memory. Modbus TCP, a standard v The application protocol is identical on Modbus serial link and Modbus TCP; messages can be routed from one network to the other without converting the protocol. v Since Modbus operates on the TCP/IP higher layer, users benefit from IP routing, thus enabling devices located anywhere in the world to communicate without worrying about the distance between them. Modbus and Modbus TCP are recognized as a fieldbus by the international standard IEC/EN 61158. They also comply with the national Chinese standard managed by ITEI. The Modbus TCP protocol uses a client/server architecture for data exchanges.

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