Viconics VT8600 Series BACnet Integration Guide - Manual (Page 25)

VT8600 Series BACnet
®
Integration Manual 25
Viconics Technologies Inc. | 9245 Langelier Blvd. | St.-Leonard | Quebec | Canada | H1P 3K9 | Tel: (514) 321-5660 | Fax: (514) 321-4150
028-0437-00 www.viconics.com | [email protected] March 2015
©
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Figure 4 shows one node for the main SC panel and 4 for the controllers, for a total of 5 nodes. If there are
more than 64 devices, install repeaters to extend the network.
Maximum Cable Length
The maximum length of a chain is related to its transmission speed. The longer the chain, the slower the
speed. Using proper cable, the maximum length of an EIA-485 daisy chain is 4000-ft (1200 m). This only works
reliably for data rates up to 100,000 bps. Viconics maximum data rate is 76,800 bps. If you require a maximum
network length of more than 4000 feet, repeaters are required to extend the network.
EIA-485 Repeaters
If you have more than 64 devices, or require a maximum network length of more than 4000 feet, repeaters are
required to extend the network.
End Of Line (EOL) Resistors
Figure-5 Correct Repeater Use in an EIA-485 Network
Figure 4 : Example Network - 5 Nodes
EOL
Resistor
EOL
Resistor
EOL
Resistor
EOL
Resistor
EOL
Resistor
EOL
Resistor
EOL
Resistor
EOL
Resistor
SC
Supervisory
Controller
Repeater
Repeater
Repeater
Node 1 Node 2 Node 3 Node 4 Node 5
*NOTE: End Of Line resistors do not count as nodes.
EOL
Resistor
SC
Supervisory
Controller
EOL
Resistor