Can Technology - WAGO -I/O-SYSTEM 750 Manual

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CAN Technology

Pos : 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 @ 1
3 CAN Technology
The CAN bus is a an asynchronous serial bus system for connecting intelligent
actuators and sensors to the control level. CAN standards for "Controller Area
network" and defines a communication standard developed in the mid-1980s for
data transmission in automobiles.
The so-called "Data Link Layer" is defined in the CAN specification. This is the
physical 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 CAN
specification. CAL is a general description language for CAN networks and
makes a number of communication services available.
Network management powers up the network in a simplified manner. This
network can be extended by the user as required.
CAN is a so-called "Multi-Master Bus System". Contrary to other fieldbus
systems, the I/O modules connected to the bus are not addressed, but the messages
are identified. The devices are allowed to send messages whenever the bus is
available. Bus conflicts are solved by assigning messages a specific priority. This
priority is defined by the so-called "CAN-ID" (CAN identifier). It is uniquely
assigned to a communication object. The smaller the identifier, the higher the
priority. 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
identifiers. The "2.0B Extended Frame" was later developed to support up to 2
different CAN identifiers.
Each bus node decides by itself when it wants to send data. However, it is also
possible 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 higher
layers. These may include CANopen, DeviceNet and SAE J1939. Support for
these protocols is left to future module variants.
Additional information about the CAN bus!
Additional information about the CAN bus is available on the Internet at
www.can-cia.org.
WAGO-I/O-SYSTEM 750
Version 1.2.0, valid from FW/HW-Version 01/01
750-658 CAN Gateway
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different CAN
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Manual