Delta Controls
Document Edition 2.3
Page 9 of 13
Mounting
The back plate is designed for mounting directly on a standard North American, European
or Australian electrical box, but may be mounted in other ways as well. The back plate is
screwed into the dry wall or electrical box and the faceplate snaps into place on top. Use
the hex screw located on the bottom of the housing to secure the faceplate to the back
plate.
Power (Only RTS-20Jxx)
The Room Temperature Sensor with the Service Port option requires a 24 VAC @ 2VA
power supply, typically an isolated Class 2 transformer. More than one device – not
including DCUs or V2 products – may be connected to the same transformer, providing the
transformer is properly sized, including line losses, and polarity is observed between
controllers (in regards to 24~ and GND). The transformer must
ONLY
be used to provide
power to other MS/TP devices. Auxiliary field devices (i.e., 4-20 mA devices) that don’t
use ½ wave rectification must be powered separately.
Network & Cabling Requirements (Only RTS-20Jxx)
To ensure network stability and reliable communications when using the Service Port
option, particularly at high speeds on a BACnet RS-485 MS/TP network, it is imperative
that you adhere to the following network and cabling requirements:
Item
Description
Cabling
For BACnet MS/TP 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
For BACnet MS/TP networks, ensure the cable is installed as a
daisy-chain
from one device to the next.
Max. Nodes The maximum number of devices per BACnet MS/TP network without any
repeaters is
50
.
Termination
Boards
A termination board
must
be installed at each end of each BACnet MS/TP
network segment – or two per BACnet MS/TP 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 network beyond 4000 ft (1220
m).
