Delta Controls
Power
The DNT-T221 requires a 24V AC Class 2 power supply rated for at least 15 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, if
the transformer is properly sized (including line losses), and the 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 and Installation Guidelines.
Network & Cabling Requirements
Adhere to the following network and cabling requirements to ensure network stability and reliable
communications, particularly at high speeds on the RS-485 MS/TP or LINKnet networks.
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 Ω 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 the Appendix on
Working with MS/TP
and LINKnet
in the Technical Reference Manual for more information.)
Termination
Boards
• MS/TP: A termination resistor must be jumper selected at each end of each MS/TP network
segment. Ensure you do not overlook this in laying out your network architecture.
• LINKnet: Jumper select a termination resistor on each end of the network when there
are more than 2 nodes. Termination resistors do not need to be installed for one or two
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 and Installation Guidelines.
Document Edition 1.8
Page 7 of 10
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