CHAPTER 35
Network connection
405.1200.037.2 - Rel.: 2.21 of 25/02/2008
35-24
CAN VT terminals equipped with the appropriate interface can be connected in a
network with other devices by means of a CAN (Controller Area Network)
protocol.
CAN terminals correspond to CIA DS 102 Version 2.0 (CAN Physical
Layer for Industrial Applications) specifications.
The CAN network differs from other types of network in its low cost, high
level performance in difficult electrical conditions, exceptional ability to
respond in real time and operational simplicity.
This type of network has a master/slave structure. The master device takes
care of initializing and configuring the slave stations, and further with con-
trolling the communication state of the devices in the network. The slave
devices are concerned exclusively with exchange of information. To be
able to communicate, the slave devices must be initialized (operational
state) and parameterized by the master device.
The VT can work at a speed ranging from 10kbit/s to 1000kbit/s.
CAN: VT
functioning in
CAN network
The VTs communicate with the devices using logical channels to which
there correspond virtual communication lines which are independent of one
another and definible using certain parameters.
Logical channels can be of one of two types:
• SDO (Service data object)
• PDO (Process data object)
SDO channels concern themselves with the exchange of parameters for set-
ting, configuring and other information regarding the setting of the device.
PDO channels, on the other hand, concern themselves exclusively with
exchanging information related to the process underway.
PDO channels have priority over SDO channels.
It is possible to define the identifiers and lines of communication for all
SDOs and PDOs by using the TX and RX parameters; admissible values
run from 1 to 65535.
The network participants must each have a different address; the address of
the terminal is configured using VTWIN (see Software Manual).
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