Power; Network Cabling & Requirements - Delta Controls BACstat II Installation Manual

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.
• MS/TP: The maximum number of devices per MS/TP network without any repeaters is 50.
Max. Nodes
• 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.)
• MS/TP: A termination board must be installed at each end of each MS/TP network segment
Termination
– or two per MS/TP or LINKnet network. Ensure you do not overlook this in laying out
Boards
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.
• MS/TP: A repeater (RPT-768) is not necessary unless more than 50 nodes will be installed
Repeater
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.
Document Edition 1.6
Delta Controls
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