Distech Controls ECLYPSE APEX, Руководство пользователя

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126 ECLYPSE APEX
A repeater can be used to create a spur as shown below.
EOL Externally Set
END
EOL ON
ECLYPSE
Figure 102: Adding a Spur by Using a Repeater
A repeater is counted as a device on each data bus to which it is connected.
When third party devices are connected to a data bus segment, the number of devices that can be
connected to that data bus segment may be reduced. See
Device Loading .
Data Bus Shields: Twist
together and Isolate
with electrical tape
Typical BACnet Device
Data Bus: Shielded
Twisted Pair Cable
N
E
T
+
N
E
T
-
N
E
T
+
N
E
T
-
The data bus shield must be connected to the electrical system ground at
one point only – usually at the Building Controller, when present
12
0
Ω
Data Bus Shields: Twist
together and Isolate with
electrical tape
EOL ON
BACnet MS/TP data bus
Bias and EOL termination is
provided by this controller’s
internal EOL Termination
being set to ON
< 7.6 m
< 25 ft
1 2
Typical
BACnet
Device
No Built-in EOL
Termination
Typical BACnet Device
N
E
T
+
N
E
T
-
EOL ON
BACnet MS/TP data bus
Bias and EOL termination is
provided by this controller’s
internal EOL Termination
being set to ON
Repeater
Data + (1)
Data – (2)
Data + (20)
Data – (19)
Figure 103: Repeater Connections when it is the First or Last Device on its Respective Data Bus Segment
The BACnet MS/TP Data Bus must be biased. This bias can only be provided by built-in EOL termina-
tion resistors (ones set with a jumper or DIP switch). When a repeater is the first or last device on its
respective data bus segment, use the following methods to provide MS/TP Data Bus biasing and EOL
termination as applicable to your situation:
1. On the BACnet MS/TP data bus segment ❶ shown in the above figure, bias and EOL termination
is provided by a controller’s built-in EOL termination being set to ON. In this case the connection to
the repeater cannot be more than 7.6 meters (25 feet) from this controller.
2. On the BACnet MS/TP data bus segment ❷ shown in the above figure, a 120Ω EOL Termination
resistor is added to the repeater’s terminals. Biasing for this BACnet MS/TP data bus segment is
provided by the built-in EOL termination being set to ON at the last controller at the other end of
this data bus.
BACnet MS/TP Communication Data Bus Fundamentals