Interfaces for communication
Ethernet
Ethernet is a hard-wired data network technology for local data networks (LAN = L o-cal A rea N etwork). Ethernet permits data to be exchanged in the form of data frames between all devices connected to the local data network (
industrial computers,
industrial printers, etc.). Nowadays, Ethernet technology also links devices over long distances. The main constituents of Ethernet are:•Definitions of cable types and
connectors manufacturers•Description of signalling for bit transmission layer•Definition of package formats and protocols In terms of the OSI model ( O pen S ystems I nterconnections), Ethernet specifies OSI layer 1 (physical layer) and OSI layer 2 (data link layer). To a large extend, Ethernet is standardised in the IEEE standard 802.3. It became the biggest selling LAN tech-nology in the 1990s and has displaced other LAN standards such as Token Ring, FDDI and ARCNET. For Berger Lahr, Ethernet forms the basis of the TCP/IP network protocol that permits data to be exchanged beyond local networks.
ApplicationEthernet FTP FTP FTP SMTP SMTP SMTP HTTP HTTP HTTP DNS DNS DNS DHCP DHCP DHCP … Ethernet … … t Ethernet TCP TCP TCP UDP UDP UDP NetworkTranspor IP IP IP ARP ARP ARP Network access Ethernet in the OSI layer model CANopen
CANopen is a communication protocol based on CAN ( C ontroller A rea N etwork) for the OSI layer7 (application layer) that is chiefly used in automation engineering. CANopen has been the responsibility of the CiA Organization (CiA = C AN i n A utoma-tion) since 1995 and has now been standardized in European Standard EN50325-4. The communication protocol is based on the principle of a message distribution sys-tem and, thanks to its particular performance characteristics and the inexpensive pro-tocol blocks, permits a wide variety of innovative system solutions. Important properties of CANopen:•The data transmission rate depends on the length of a network cable: 40m at 1Mbit/s; 1000m at 50kbit/s etc.•Inexpensive twisted-pair 2-wire cable with terminating resistors•Object-oriented messages, broad and multitasking with acceptance check•Maximum data transmission rate 1Mbit/s•Very high data security (HK=6); error detection and signalling, automatic switch-off of defective stations•Open system (ISO 11898 and CiA DS 301, DS 405)PROFIBUS (
Profibus-DP
Pro cess Fi eld Bus ) is a recognised standard for
field network communication in automation engineering, and was initially promoted by the German Federal Ministry for Research and Technology. Berger Lahr uses PROFIBUS-DP (DP = D ecentralized P eriphals) because it provides many diagnostic possibilities as standard. The most important area of application for PROFIBUS-DP is networking several con-trollers together (distributed intelligence). PROFIBUS permits data transmission rates of up to 12Mbit/s on twisted 2-wire
professional cables.
42Catalogue Motion ControllerBerger Lahr