Installation And Set-Up - Danfoss VLT FC 102 Series Design Manual

Installation and Set-up

8 Installation and Set-up
8.1 Installation and Set-up
8.1.1 Overview
RS-485 is a two-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 one 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 adjustable frequency
drives or a biased termination resistor network. Always use
shielded twisted pair (STP) cable for bus cabling, and
always follow good common installation practice.
Low-impedance ground connection of the shield at every
node is important, including at high frequencies. Thus,
connect a large surface of the shield to ground, for
example with a cable clamp or a conductive cable
connector. It may be necessary to 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 adjustable frequency drive,
always use shielded motor cable.
Cable Shielded twisted pair (STP)
Impedance 120
[Ω]
Cable length Max. 4,000 ft [1200 m] (including drop lines)
(ft [m]) Max. 1,650 ft [500 m] station-to-station
Table 8.1 Cable Specifications
One or more adjustable frequency drives can be connected
to a control (or master) using the RS-485 standardized
interface. Terminal 68 is connected to the P signal
(TX+, RX+), while terminal 69 is connected to the N signal
(TX-,RX-). See drawings in chapter 6.8.3 Grounding of
Shielded Control Cables.
MG11BC22
Design Guide
If more than one adjustable frequency drive is connected
to a master, use parallel connections.
Figure 8.1 Parallel Connections
To avoid potential equalizing currents in the shield, ground
the cable shield via terminal 61, which is connected to the
frame via an RC link.
61 68 69
Figure 8.2 Control Card Terminals
Danfoss A/S © Rev. 06/2014 All rights reserved.
RS 232
68 69 68
+
USB
-
RS 485
39 42 50 53 54 55
Remove jumper to enable Safe Stop
12 13 18 19 27 29 32 33
69 68 69
8 8
20 37
145