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4.8.6 RS-485 Serial Communication

Up to 32 nodes can be connected as a bus, or via drop

cables from a common trunk line to 1 network segment.

Repeaters can divide network segments. Each repeater

functions as a node within the segment in which it is

installed. Each node connected within a given network

must have a unique node address, across all segments.

•

Connect RS-485 serial communication wiring to

terminals (+)68 and (-)69.

•

Terminate each segment at both ends, using

either the termination switch (bus term on/off,

see Illustration 4.13) on the frequency converters,

or a biased termination resistor network.

•

Connect a large surface of the screen to ground,

for example with a cable clamp or a conductive

cable gland.

•

Apply potential-equalising cables to maintain the

same ground potential throughout the network.

•

Use the same type of cable throughout the entire

network to prevent impedance mismatch.

Cable

Screened twisted pair (STP)

Impedance

120 Ω

Max. cable

length [m]

1200 (including drop lines)

500 station-to-station

Table 4.4 Cable Information

Electrical Installation

VLT

HVAC Drive Operating Instructions

MG11AJ02 - Rev. 2013-07-31 19

4 4

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 73 74

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Danfoss 102 Instrucciones de operaciones Pagina 21