WAGO WAGO-I/O-SYSTEM 750 Manual

Also see for I/O-SYSTEM 750: Manual Manual Technical description User's installation and configuration Manual

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WAGO WAGO-I/O-SYSTEM 750 Manual Manual pdf 14 page image

14 CAN Technology WAGO-I/O-SYSTEM 750750-658 CAN GatewayManualVersion 1.2.0, valid from FW/HW-Version 01/01Pos : 18 /Serie 750 ( WAGO-I/O-SYST EM)/F eldbus kommuni kation/C AN/C AN-Kommuni kation 750-0658 @ 13\mod_1355479155100_21.doc x @ 107624 @ 1 @ 13 CAN TechnologyThe CAN bus is a an asynchronous serial bus system for connecting intelligentactuators and sensors to the control level. CAN standards for "Controller Areanetwork" and defines a communication standard developed in the mid-1980s fordata transmission in automobiles.The so-called "Data Link Layer" is defined in the CAN specification. This is thephysical layer and data data link layer. The message format is described in detail.In addition, the so-called "CAN Application Layer" (CAL) is defined in the CANspecification. CAL is a general description language for CAN networks andmakes a number of communication services available.Network management powers up the network in a simplified manner. Thisnetwork can be extended by the user as required.CAN is a so-called "Multi-Master Bus System". Contrary to other fieldbussystems, the I/O modules connected to the bus are not addressed, but the messagesare identified. The devices are allowed to send messages whenever the bus isavailable. Bus conflicts are solved by assigning messages a specific priority. Thispriority is defined by the so-called "CAN-ID" (CAN identifier). It is uniquelyassigned to a communication object. The smaller the identifier, the higher thepriority. Thus, communication without bus master module is thus also possible.There are two CAN standards:• "2.0A Standard Frame"• "2.0B Extended Frame"The "2.0A Standard Frame" makes it possible to address up to 2 11 different CANidentifiers. The "2.0B Extended Frame" was later developed to support up to 2 29different CAN identifiers.Each bus node decides by itself when it wants to send data. However, it is alsopossible to request other bus nodes to send data. This request happens via the so-called "Remote Frame".Based on CAN, various protocols have been established on the market at higherlayers. These may include CANopen, DeviceNet and SAE J1939. Support forthese protocols is left to future module variants.Additional information about the CAN bus!Additional information about the CAN bus is available on the Internet atwww.can-cia.org.