Distech Controls ECL/ECB-PTU Series User Manual page 32

Figure 18: Repeater Connections when it is the First or Last Device on its Respective Data Bus Segment
Typical BACnet Device
EOL ON
1
Data Bus: Shielded
Twisted Pair Cable
< 7.6 m
< 25 ft
The BACnet MS/TP Data Bus must be biased. This bias can only be provided by built-in EOL
termination 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  shown in
is provided by a controller's built-in EOL termination being set to ON. In this case the con-
nection to the repeater cannot be more than 7.6 meters (25 feet) from this controller.
2. On the BACnet MS/TP data bus segment  shown in
resistor is added to the repeater's terminals. Biasing for this BACnet MS/TP data bus seg-
ment is provided by the built-in EOL termination being set to ON at the last controller at the
other end of this data bus.
See When to Use EOL Terminations
bus must be grounded at one point as specified in see
ments on page 24. The shields of the two data buses must be connected together and isolated
with electrical tape as shown in
for how to identify and set a controller's built-in EOL terminations.
30
BACnet MS/TP data bus
Bias and EOL termination is
provided by this controller's
internal EOL Termination
being set to ON
Data Bus Shields: Twist
together and Isolate with
electrical tape
Repeater
Data + (1) Data + (20)
Data – (2) Data – (19)
on page 20 for more information. The shield of one data
Figure 18. Refer to the controller's Hardware Installation Guide
BACnet MS/TP data bus
Typical
Bias and EOL termination is
BACnet
provided by this controller's
Device
internal EOL Termination
No Built -in EOL
being set to ON
Termination
Data Bus Shields: Twist
together and Isolate
with electrical tape
2
The data bus shield must be connected to the electrical system ground at
one point only – usually at the Building Controller , when present
Figure 18, bias and EOL termination
Figure 18, a 120Ω EOL Termination
Data Bus Shield Grounding Require-
Typical BACnet Device
EOL ON
Network Guide