Specifications

7 Installation and Set-up
7.1 Installation and Set-up
RS-485 is a 2-wire bus interface compatible with multi-drop
network topology, i.e. 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 one network segment.
Repeaters divide network segments. Note that 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 screened
twisted pair (STP) cable for bus cabling, and always follow
good common installation practice.
Low-impedance earth connection of the screen at every
node is important. Connect a large surface of the screen to
earth with a cable clamp or a conductive cable gland. If
needed, apply potential-equalizing cables to maintain the
same earth 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
screened motor cable.
Cable: Screened twisted pair (STP)
Impedance: 120 Ω
Cable length: Max. 1200 m (including drop lines)
Max. 500 m station-to-station
Table 7.1 Motor Cable Specifications
7.1.1 Network Connection
One or more frequency converters can be connected to a
control (or master) using the RS-485 standardised interface.
Terminal 68 is connected to the P signal (TX+, RX+), while
terminal 69 is connected to the N signal (TX-,RX-). See
5.6.2 Safety Earth Connection 5.7.3 Earthing of Screened/
Armoured Control Cables
If more than one frequency converter is connected to a
master, use parallel connections.
130BA060.11
68 69 68 69 68 69
RS 485
RS 232
USB
+
-
Illustration 7.1 Parallel Connections
To avoid potential equalizing currents in the screen, earth
the cable screen via terminal 61, which is connected to the
frame with an RC-link.
130BB021.10
12 13 18 1927 29 32
33 20 37
Remove jumper to enable Safe Stop
61 68 693942505354 55
Illustration 7.2 Control Card Terminals
7.1.2 Hardware Setup
Use the terminator dip switch on the main control board
of the frequency converter to terminate the RS-485 bus.
1 2
S801
ON
130BA272.11
Illustration 7.3 Terminator Switch Factory Setting
Installation and Set-up VLT® HVAC Drive FC 102 Design Guide
162 MG16C102 - Rev. 2013-08-20
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