ED15117
11
Network Considerations
Access to Properties
Object properties are accessible from the network by specifying the device object identifier, object
identifier, and the property identifier. To access a property, you must specify the object identifier
including the device object identifier or the object name including the device object name and the
property identifier.
BACnet Networks
The BACnet communication module supports three separate BACnet data link layers:
BACnet MS/TP
BACnet Ethernet
BACnet/IP
Only one data link layer may be used at one time.
During initialization, the BACnet communication module reads a parameter in the Magnitude Chiller
Unit Controller to select the data link layer. If the value read is not one of the supported BACnet data
link layers, the BACnet communication module initialization loops in this phase of the initialization
until a supported BACnet data link layer value is read from the unit controller. The BACnet
communication module’s active data link layer may not be changed at run-time. If the unit controller
parameter is changed during run-time, the BACnet communication module requires a reset in order to
re-initialize with the new data link layer selection.
The different data link layers have different parameters. All parameters that require configuration are
read from the unit controller by the BACnet communication module via the unit controller OITS panel.
The BACnet communication module reads only those parameters relevant to the selected data link
layer. During initialization, the BACnet communication module must read a complete set of valid
parameters for the BACnet network layer and selected data link layer before proceeding to build a set
of BACnet objects for the device.
BACnet Ethernet Communications Parameters
None of the Ethernet Data Link Layer or Physical layer parameters require configuration.
BACnet/IP Communications Parameters
The key parameters for setting up BACnet/IP are described in the following sub-sections. The
parameters are accessible and configurable via the unit controller OITS panel. They are not accessible
from the BACnet network.
IP Address
The IP address is read from a parameter in the Magnitude Chiller Unit Controller during the BACnet
communication module’s initialization phase. The BACnet communication module can be configured
for Dynamic Host Configuration Protocol (DHCP) addressing by setting the IP Address to 0.0.0.0
using the unit controller OITS panel. The BACnet communication module continues to poll the IP
address parameter during run-time. If the IP address is changed at the unit controller during run-time,
the update is automatically applied to the BACnet communication module as soon as the change is
received. The validity of the IP address is verified against the Subnet Mask. If the address is not valid,
BACnet/IP communications cannot be established and the device does not initiate or respond to
BACnet messages. If the IP address is changed at run-time and the IP address is not valid, BACnet/IP
