130B
T306.10
Illustration 2.18
2.5.6 Control Terminal Functions
Frequency converter functions are commanded by
receiving control input signals.
•
Each terminal must be programmed for the
function it will be supporting in the parameters
associated with that terminal. See
and
for terminals and
associated parameters.
•
It is important to confirm that the control
terminal is programmed for the correct function.
See
for details on accessing
parameters and programming.
•
The default terminal programming is intended to
initiate frequency converter functioning in a
typical operational mode.
2.6 Serial Communication
RS-485 is a two-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. 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 converter 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 (ground) connection of the screen at
every node is important, including at high frequencies.
Thus, connect a large surface of the screen to earth
(ground), for example with a cable clamp or a conductive
cable gland. It may be necessary to apply potential-
equalizing cables to maintain the same earth (ground)
potential throughout the network. Particularly in instal-
lations 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
Max. cable length
1200 m (including drop lines)
500 m station-to-station
Table 2.5
Installation
VLT
®
HVAC Drive D-Frame
Operating Instructions
18
MG16D102 - VLT
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is a registered Danfoss trademark
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