ED15117
15
Configuring the Unit Controller
The Magnitude Chiller Unit Controller can operate with the default values of the various parameters.
However, certain communication parameters must be configured appropriately (see the appropriate
Magnitude Communication Module Installation Manual for details). Default values may be changed
using the unit controller OITS panel or via the BACnet network (see the Magnitude Chiller Unit
Controller Operation & Maintenance Manual, OM 1034 for details).
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Networks
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technology, developed by Echelon Corporation, is the basis for L
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Interoperable
Systems. This technology is independent of the communication media. The L
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Interoperable
Association has developed standards for interoperable L
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technology systems. In particular
they have published standards for HVAC equipment including the Chiller Functional profile. This
profile specifies a number of mandatory and optional standard network variables and standard
configuration parameters. This manual defines the variables and parameters available in the Magnitude
Chiller Unit Controller.
Compatibility
The Magnitude Chiller Unit Controller, along with the L
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Communication Module, operates
in accordance with the Chiller Functional profile of the L
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Interoperability Association.
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Variables
The Magnitude Chiller Unit Controller incorporates L
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network variables to access unit data
points. The controller uses L
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Standard Network Variable Types (SNVT) from the profile.
Some data points can be adjusted (input network variables, nvi) (read/write attributes, e.g., setpoints)
from the network and others can only be interrogated (network variables, nvo) (read only attributes,
e.g., status information). Configuration variables (nci) are included with the input network variables.
Each data point accessible from a L
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network is described with a table that gives the
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Name, Profile, SNVT Type, and SNVT Index. If the variable is a configuration variable
the table also includes the SCPT (Standard Configuration Parameter Type) Reference and the SCPT
Index.
Example of L
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Data Point
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Name
Profile
SNVT Type
SNVT Index
SNVT Size
nvoSuctionTemp McQuayChiller SNVT_temp_p
105
two
bytes
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Name
Each network variable has a name that you use to access the data point. This is the name of the variable
from the profile. In the example above, the name of the variable is nvoSuctionTemp.
Profile
The profile column designates whether the variable is defined in the L
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Chiller functional
profile or is a McQuay proprietary variable. The variable itself may not be a standard component of the
profile, but the unit controller implements it and it is available to the network. The Profile column
indicates “Chiller” for L
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standard network variables or “McQuayChiller” for proprietary
variables.
SNVT Type
This column gives the name of the standard network variable type from the master list. In the example
above, the SNVT is SNVT_temp_p.
