Owner manual

Chapter 3 ________________________________________________________________ Installation
VAISALA ________________________________________________________________________ 29
Wiring GMW95
The RS-485 line of the transmitter is isolated from the power supply. A
separate ground reference terminal (GND) is provided for the RS-485
connection.
If you are using a shielded cable, you can use the Shld terminal to hold
the exposed part of the shield. Note that the Shld terminal is floating
(not electrically connected).
1209-014
Figure 18 Wiring GMW95
Connecting Several Transmitters on Same RS-485
Line
Set the RS-485 termination jumper to “ON” on the transmitter that is at
the end of the line. This terminates the line with a 120 Ω resistor. For
location of the jumper, see Figure 4 on page 17.
Connect the cable shield to ground on the building controller side.
1209-015
Figure 19 Several Transmitters on Same RS-485 Line
D- -VsD+ +Vs
+
-
Power supply
18 ... 35 VDC
or 24 VAC ±
20
%
RS
-485
S
h
ld
GN
D
Transmit
te
r
D-
-Vs
D+
+Vs
Shld
GND
B
uil
din
g con
tro
lle
r Tr
ansm
itt
er Transmi
tt
er
Power
su
ppl
y
D-
D+
+Vs
-Vs
GN
D
SHIEL
D
RS-485:
BACne
t or
MO DBU
S
master
Connect shield on
contro
ller side
Set RS-485
termination j
umper
D-
-Vs
D+
+V
s
Shld
GND
D-
-V
s
D+
+Vs
Sh
ld
G
ND