Baumer BA_DSRT_22DJ - Handbuch (Seite 11)

Manual_CANopen_StrainLink_EN_V3_05.doc 11/65 Baumer
22.07.11/dam Frauenfeld, Switzerland
4.2 Signals, structure and bus topology
4.2.1 Bus signals
Good electrical noise immunity is achieved, among other measures, in that one bit is transmitted differentially
on two lines. The CAN-High and CAN-Low lines contain the inverted and the non-inverted serial data signal.
The state having two different levels on CAN-H and CAN-L is known as the dominant state. The state having
two equal levels is known as the recessive state.
According to the CAN definition, the dominant state corresponds to a logical zero (bus drivers have an open
collector output).
If a node puts a logical zero on the bus, it overwrites the state of a logical one from a different node.
4.2.2 Network topology
The CAN architecture used as a basis defines the physical structures of the CANopen network. This is based
on a bus (line) topology. To avoid signal reflections, the ends of the network must be terminated using a
termination resistor (120 ohm).
In addition, pay attention to the maximum stub length for connecting the individual network nodes.
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