Wiring
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Internal structure
4.3.4 RS485 Bus Wiring Instructions
● Do not bundle the extension cable together with power cables (high voltage, large current) which produce
strong interference signals. Separate it from other cables and avoid cabling in parallel.
● Select recommended cables and pinboards for connection. It is recommended that shielded cables be used as
extension cables to enhance capacity of resisting interference.
The figure below shows the RS485 bus topology. It is recommended that you use the shielded twisted
pair as the RS485 bus. The 485+ and 485− wires form a twisted pair. A 120 Ω termination resistor is
attached to each end of the bus to prevent signal reflection. All RS485 reference grounds are
connected together. Up to 128 nodes can be connected and the length of each cable connecting a
node and the bus must be less than 3 m.
● RS485 topology
The figure below shows the RS485 bus topology. It is recommended that you use the shielded
twisted pair as the RS485 bus. The 485+ and 485− wires form a twisted pair. A 120 Ω termination
resistor is attached to each end of the bus to prevent signal reflection. All RS485 reference grounds
are connected together. Up to 128 nodes can be connected and the length of each cable connecting
a node and the bus must be less than 3 m.
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