Viconics VBZS Engineering Guide Specifications - Manual (Page 3)

(4000 feet), repeaters shall be used to ensure proper communication. With repeaters and a BACnet
MS_TP supervisory system, the maximum number of nodes on a single BACnet MS_TP trunk can be
extended to 128 nodes (of either type of controller).
Overall system architecture shall be open-standard based upon Building Automation Control network
(BACnet) standard facilitating the future replacement or addition of other system components, quickly and
easily. System functionality shall be scalable to suit current and future building automation needs with
simple addition of other BACnet based building controllers. System shall support supervisory functionality
(supplied by others) which will support centralized scheduling, alarming and trending found commonplace
amongst today’s advanced automation systems.
Systems not capable of supporting supervisory BACnet workstations shall not be acceptable.
Communication Wiring and Layout – The wire shall be a balanced 22-24 AWG twisted pair with a
characteristic impedance of 100-130ohms, capacitance of 17 pF/ft or lower, with a braided shield. The
RS485 network requires a daisy chain configuration. A BACnet MS_TP network must be properly
terminated at each end of the daisy chain with an EOL (End of line) resistor. The polarity of the network
connections must be respected.
Functionality – The VBZS shall be capable of operating without external input from a supervisory
system. The control system however, shall be capable of communicating with any 3
rd
party BACnet
MS_TP compatible supervisory system, graphic user interface, charts and log software, advanced energy
management software, automatic response to alarms etc.