80 • Fieldbus CommunicationETHERNETWAGO-I/O-SYSTEM 750ETHERNET TCP/IPThe advantage of this protocol is in the efficiency of the transmitteddata and the resultant increase in processing speed.Many programs use both protocols. Important status information issent via the reliable TCP connection, while the main stream of datais sent via UDP.(3) TCP, UDP(2) IP(1) Ethernet(physical interface, CSMA/CD)(4) Management, Diagnostic and Application Protocols:Positioned above the TCP/IP stack or UDP/IP layer are correspondinglyimplemented management, diagnostic and application protocols that provideservices that are appropriate for the application. For the management anddiagnostic, these are, for example, SMTP (Simple Mail Transport Protocol)for e-mails, HTTP (Hypertext Transport Protocol) for www browsers andsome others.In this example, the protocols MODBUS/TCP (UDP) and EtherNet/IP areimplemented for use in industrial data communication.Here the MODBUS protocol is also positioned directly above TCP (UDP)/IP;EtherNet/IP, on the other hand, basically consists of the protocol layersEthernet, TCP and IP with an encapsulation protocol positioned above it. Thisserves as interface to CIP (Control and Information Protocol).DeviceNet uses CIP in the same way as EtherNet/IP. Applications withDeviceNet device profiles can therefore be very simply transferred toEtherNet/IP.Application device profiles(e.g. positioning controllers, semi-conductors, pneumatic valves)CIP application objects libraryCIP data management services(explicit messages, I/O messages)Mail clientWWW browser...CIP message routing, connectionmanagementCIP(4)SMTPHTTP...MODBUSEncapsulationprotocol(3) TCP, UDP(2) IP(1) Ethernet(physical interface, CSMA/CD)ETHERNET/IP
