FC101 Design Guide

7 RS485 Installation and Set-up
7.1 RS485
7.1.1 Overview
RS485 is a 2-wire bus interface compatible with multi-drop
network topology, that is, nodes can be connected as a
bus, or via drop cables from a common trunk line. A total
of 32 nodes can be connected to 1 network segment.
Repeaters divide network segments.
NOTICE!
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.
Terminate each segment at both ends, using either the
termination switch (S801) of the frequency converters or a
biased termination resistor network. Always use shielded
twisted pair (STP) cable for bus cabling, and follow good
common installation practice.
Low-impedance ground connection of the shield at every
node is important. Connect a large surface of the shield to
ground, for example with a cable clamp or a conductive
cable gland. Apply potential-equalizing cables to maintain
the same ground potential throughout the network -
particularly in installations with long cables.
To prevent impedance mismatch, always use the same
type of cable throughout the entire network. When
connecting a motor to the frequency converter, always use
shielded motor cable.
Cable Shielded twisted pair (STP)
Impedance [Ω]
120
Cable length
[m (ft)]
Maximum 1200 (3937) (including drop lines).
Maximum 500 (1640) station-to-station.
Table 7.1 Cable Specications
7.1.2 Network Connection
Connect the frequency converter to the RS485 network as
follows (see also Figure 7.1):
1. Connect signal wires to terminal 68 (P+) and
terminal 69 (N-) on the main control board of the
frequency converter.
2. Connect the cable shield to the cable clamps.
NOTICE!
To reduce noise between conductors, use shielded,
twisted-pair cables.
61 68 69
N P COMM. GND
130BB795.10
Figure 7.1 Network Connection
7.1.3 Frequency Converter Hardware Set-up
Use the terminator dip switch on the main control board
of the frequency converter to terminate the RS485 bus.
130BG049.10
Figure 7.2 Terminator Switch Factory Setting
The factory setting for the dip switch is OFF.
RS485 Installation and Set-...
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