Distech Controls ECB-VAV, User Manual

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26 Network Guide
Figure 11: : Typical Cable-Shield Grounding Requirements for a BACnet MS/TP Data Bus Segment with
a Building Controller located in the Middle of the Data Bus
Figure 12: Typical Cable-Shield Grounding Requirements for a BACnet MS/TP Data Bus Segment without
Building Controller
Data Bus Shield Grounding Requirements When Mixing Both
ECB 24V-Powered Controllers and ECB-PTU Line-Powered
Controllers
The shield on each data bus segment must be connected to the electrical system ground at
one point only, for example, at the Data Bus Master (Building Controller) if there is one, as
shown below in
Figure 13 and Figure 14 . On data bus segments without a Data Bus Master,
the ideal point to ground the shield is in the middle of the data bus segment as shown in Figure
15 .
Figure 13: Typical Cable-Shield Grounding Requirements for a BACnet MS/TP Data Bus Segment with a Building
Controller located in the End of the Data Bus
Data Bus: Shielded Twisted Pair Cable
Bus Master (Building Controller)
Typical EC-BOS Device
+ - S
Data Bus Shields:
Connect to the ‘S’
terminal
Typical BACnet Line-
Powered Controller
Data Bus Shields: Twist
Together and Connect
to ‘COM’ Terminal
NE
T
-
NE
T
+
CO
M
Typical BACnet Line-
Powered Controller
Data Bus Shield:
Connect to ‘COM’
Terminal
NE
T
-
NE
T
+
CO
M
Typical BACnet Line-
Powered Controller
Data Bus Shield:
Connect to ‘COM’
Terminal
NE
T
-
NE
T
+
CO
M
Typical BACnet Line-
Powered Controller
Data Bus Shields: Twist
Together and Connect
to ‘COM’ Terminal
NE
T
-
NE
T
+
CO
M
Electrical
System
Ground
The shield of the data bus must be connected to
the electrical system ground at one point only –
usually at the Building Controller , when present
Data Bus: Shielded Twisted Pair Cable
Typical BACnet Line-
Powered Controller
Data Bus Shields: Twist
Together and Connect
to ‘COM’ Terminal
NE
T
-
NE
T
+
CO
M
Typical BACnet Line-
Powered Controller
Data Bus Shields: Twist
Together and Connect
to ‘COM’ Terminal
NE
T
-
NE
T
+
CO
M
Typical BACnet Line-
Powered Controller
Data Bus Shields: Twist
Together and Connect
to ‘COM’ Terminal
NE
T
-
NE
T
+
CO
M
Typical BACnet Line-
Powered Controller
Data Bus Shields:
Connect to ‘COM’
Terminal
NE
T
-
NE
T
+
CO
M
Typical BACnet Line-
Powered Controller
Data Bus Shields:
Connect to ‘COM’
Terminal
NE
T
-
NE
T
+
CO
M
Electrical
System
Ground
The shield of the data bus must be connected to
the electrical system ground at one point only,
ideally in the middle of the data bus as shown