Delta Controls DNT-T221 Installation Guide

Delta Controls
Document Edition 1.6
Page 7 of 10
Power
The DNT-T221 BACstat II requires a 24V AC Class 2 power supply rated for at least 17 VA. This includes
output loading of the internally powered triac (0.5A max @ 24 VAC) and the two analog outputs (20mA max
each).
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 or
LINKnet devices and field devices powered through its outputs. Auxiliary field devices (i.e., 4-20 mA
devices) that don’t use ½ wave rectification must be powered separately.
For more information refer to the Delta Controls Wiring Guidelines.
Network & Cabling Requirements
To ensure network stability and reliable communications, particularly at high speeds on the RS-485 MS/TP or
LINKnet networks, it is imperative that you adhere to the following network and cabling requirements:
Item Description
Cabling For 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 For MS/TP and LINKnet networks, ensure the cable is installed as a daisy-chain from one
device to the next.
Max. Nodes
• MS/TP
: The maximum number of devices per MS/TP network without any repeaters is 50.
• LINKnet
: Up to a maximum of 12 Devices (depending on the controller), only two of
which can be DNT or DFM devices. (Refer to Appendix G in the Technical Reference
Manual for more information.)
Termination
Boards
• MS/TP
: A termination board 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.
• LINKnet
: Termination boards need not be installed for only one or two nodes.
However, install a termination board on each end of the network when there are more
than 2 nodes.
Repeater
• MS/TP
: 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).
• LINKnet
: Repeaters should not be necessary. Ensure the maximum distance is no
more than 1000 ft (300 m).
For more information refer to the Delta Controls Wiring Guidelines.

Delta Controls DNT-T221 Specifications

General

Brand	Delta Controls
Model	DNT-T221
Category	Thermostat
Language	English