I
nTroduCTIon
www.DaikinApplied.com
7
IM 968-4 • MICROTECH III CHILLER UNIT CONTROLLER
Bus Termination
Bus termination resistors are used for properly terminating
a network based on twisted pair cabling with attention to
impedance.
NOTE:
Refer to Echelon
L
on
W
orks
FTT-10A Transceiver
User’s Guide for details regarding acceptable
configurations, cabling requirements,
terminations, impedance, and other requirements
(
www.echelon.com
).
Transmission Specifications
Component
Value
Network topology
Flexible Free Topology
Neuron chip processor
3150
Free Topology Transceiver
(FTT-10A)
50051
Cable types
TIA Category 5 (recommended)
Maximum cable length
1476 ft (450 m) per segment (total of all lines)
Maximum node separation 820 ft (250 m)
Data transmission
Two-wire, half duplex
Data transmission rate
78 kbps (baud)
Bus terminator
Free topology: use one (1) 52.3
Ω
bus terminator
at the busiest point of the network
Daisy chain or standard line (dual) topology: use
two (2) 105
Ω
bus terminators at the end of both
network segments
Repeaters and routers
Repeaters and router are typically used when the
entire cable length in a given segment exceeds
1476 ft (450 m) in a free topology or 2953 ft
(900 m) in a line topology.
Each trunk can have at maximum one physical
repeater. Repeaters and routers may not be used
in a ring topology. They must be placed before
the network’s ring port.
Software Interface to Unit Controller
The
L
on
W
orks
communication module software translates
the Standard Network Variable Types (SNVTs) and Standard
Network Configuration Parameter Types (SCPTs) used in
the MicroTech III chiller unit controller into the variables and
parameters used by the
L
on
W
orks
network. The software
conforms to the LonMark 3.4 chiller profile. Refer to MicroTech
III Chiller Unit Controller Protocol Document, ED 15120 for
additional information (
www.DaikinApplied.com
).
