Nortec LINKS 2 NHRS - Manual (Page 13)

Installation | 9
Multi-Unit Systems (“Master/Slave”)
Up to 8 humidifiers can be chained and monitored through a single Links2 package. In this
configuration, the unit with the Links2 package is designated the “Master Unit”, while the
remaining 7 humidifiers are configured as “Slaves”. The master unit is connected to the Building
Management Systems (BMS). Each unit is separately addressed, it is possible to monitor and
control each unit individually.
Different networking configurations may be achieved depending on the type of network being
used. One networking example could have a Gateway installed inside the lead unit, which could
then be daisy-chained to successive units. In turn, the lead unit would connect to a Building
Management System (BMS) network via a shielded, twisted-pair connection. Please see wiring
section for additional detail. A second example could have a series of units directly connected to
an Ethernet network. This is only possible for BACnet communication and is essentially referred to
as a BACnet/IP configuration.
Wiring
BACnet MS/TP, Johnson N2, and LonWorks
Links 2 is pre-installed and factory wired. Connections must be made between the master
humidifier and the BMS, and the master humidifier and any slaves that may be present.
Connections to the BMS are through terminals A and B on the Links 2 terminal strip for BACnet
MS/TP, Johnson N2, and LonWorks. The shields should also be connected. Refer to the wiring
diagrams in this manual.
Table 2 refers to the recommended wire types and maximum recommended lengths from the
Nortec Links2 module to the Building Management system. Communication between the
humidifiers and Nortec Links2 will occur via a EIA-485 signal type. Nortec recommends using a
18-24 AWG shielded, 120
 twisted pair wire between the lead humidifier and each of the slave
humidifiers. Total cable length runs between the Nortec Links2 module and the furthest slave
humidifier should not exceed 2,000 feet. Signal boosters or repeaters may be necessary for
longer wire runs or where electrical noise interference is prevalent.
Table 2: Recommended Wire Types and Lengths
Protocol
Signal
Type
Polarity
Recommended
Cable
Maximum Recommended
Distance from NORTEC
Module
A B
BACnet MS/TP
EIA-485,
2-wire
Net + Net -
18-24 AWG
Shielded, Twisted
Pair
120  Impedance
2000 ft
Johnson N2
LonWorks
FTT-10
2-wire
Tx Rx
18-24 AWG
Twisted Pair
120  Impedance
Should not exceed 50 ft.
BACnet/IP
LAN
standard
N/A N/A
CAT.5E cable with
RJ-45 termination Depends on cable
manufacturer