Viconics VBZS Application Guide - Manual (Page 31)

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EOL: MS-TP network must be properly terminated. For daisy chain configurations, you must install an EOL
(End of Line) resistor at each end of the daisy chain (The first and the last device). For a stand-alone
system with only Viconics controllers installed on the communication network the value of the EOL resistor
is 120 Ohms ¼ watt. For EOL values used with other non-Viconics devices on the network, please refer to
the Viconics Integration Guide.
The two resistances are installed across the + and – communication terminals on both the first and last
devices on the wire. Please note that these do not necessarily represent the lowest and highest MAC
addresses given to the controllers.
Shield: The purpose of the shield is to protect the communication network from external radio noise
sources.
DO NOT WIRE THE SHIELD(s) TO THE (Ref) COMMUNICATION TERMINAL.
- The shield for the first and the last devices located behind the controller must be fully protected to
prevent accidental shorting to the ground.
- The shields for any middle device (there are two wires. One in and one out for a total of two
shields) which need to be connected together in the back of the controller while making sure they
are fully protected to prevent accidental wiring to the ground.
Shield connected in the
back of the thermostats
All the shield(s) attached and wired together need to be connected to the ground only at one location on
the whole network.