Delta Controls
Network & Cabling Requirements
To ensure network stability and reliable communications, particularly at high speeds on a BACnet MS/TP network
for a number of devices, it is imperative that you adhere to the following network and cabling requirements:
Item
Description
Cabling
For BACnet MS/TP and LINKnet networks it is recommended that you use network cabling
that matches the following specifications:
•
Balanced 100 to 120 ohm nominal impedance Twisted Shielded Pair (TSP) Cable
•
Nominal capacitance of 16 PF/FT or lower
•
Nominal velocity of propagation of 66% or higher
Topology
Ensure the MS/TP network cable is installed as a
daisy-chain
from one device to the next.
Max. Nodes
The maximum number of devices per MS/TP network without any repeaters is
50
.
Termination
Boards
A termination board (TRM-768)
must
be installed at
each end
of each MS/TP network segment
– or two per MS/TP or LINKnet network. Ensure you do not overlook this in laying out your
network architecture and ordering product.
Repeater
A repeater (RPT-768) is not necessary unless more than 50 nodes will be installed on a network
or
you need to extend the MS/TP network beyond 4000 ft (1220 m).
For more detailed information, including wiring, refer to the
RS-485 Network Installation Guide
(DOC818-11).
Document Edition 1.5
Page 9 of 15
