BIG ASS FANS BAFWorks 3.0, Installation Manual

Page: 38 / 84

BAFWORKS
®
INSTALLATION GUIDE
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32
Electrical Installation: Fans (cont.)
RS-485 Network Biasing: Lenze SMVector VFDs (Powerfoil
®
8, Basic 6
®
, Pivot
™
, & Pivot
™
180 fans)
Depending on the design of the RS-485 transmitters and receivers, biasing resistors may be required for proper data transmission. The
biasing resistors keep the data lines on the system at a fixed level while the transmitters are in an idle state. Without these resistors,
data corruption or data packet loss can occur. The SMVector Modbus cards fall within these requirements; therefore, a pair of 680 Ω
1/4 W resistors must be installed on either the first or last SMVector drive in the network series as shown below
. Due to the
presence of a 120 Ω resistor at the end of the line, Big Ass Solutions recommends installing the 680 Ω resisitors at the first fan location
to prevent clutter on the terminal strip.
5 4 3 2 1
5 4 3 2 1
ORANGE W/ WHITE
WHITE W/ ORANGE
BARE
BLUE W/ WHITE
Modbus Card
installed in
SMVector
access cover
CAUTION: Risk of short circuit
exists between terminals 2 and 4
with resistors installed. Isolate as
necessary.
Terminal 4=MBA(+) Orange/WHT
Terminal 2=MBB(-) White/ORG
Terminal 1=REF Blue/WHT & SHLD
Install a 680Ω resistor between terminals
4 and 5. Install a second 680Ω resistor
between terminals 1 and 2.
Modbus Cable
from Gateway
Modbus Cable
Data Loop Out to Fan #2
if applicable
Note: The wire colors shown above are applicable to Belden 3106A Modbus cable only. Other cable types may differ. Take note of
color/polarity if using a different model of cable.
680 Ω 1/4 W 680 Ω 1/4 W