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Foreign Device Time-To-Live
The Foreign Device Time-To-Live (FDTTL) value is read from the Magnitude Chiller Unit Controller
during the BACnet communication module’s initialization phase. The BACnet communication module
continues to poll the FDTTL parameter during run-time. If the FDTTL 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. If the new value is different from the existing value, a Register-Foreign-Device
message is sent to the BBMD address. This parameter can only be accessed and configured via the unit
controller OITS panel.
BACnet MS/TP Communication Parameters
The BACnet MS/TP communication setup parameters consist of: the Device Object Name, Device
Object Identifier, Max Master, Max_Info_Frames, MAC Address and Baud Rate. These parameters can
only be accessed and configured via the unit controller OITS panel. Both the MAC Address and the
Baud Rate settings require configuration prior to establishing communication from the unit controller
to the BACnet network.
MAC Address
The MAC address is read from a parameter in the Magnitude Chiller Unit Controller during the
BACnet communication module’s initialization phase. This parameter can only be accessed and
configured via the unit controller OITS panel. It is not accessible from the BACnet network interface
(i.e. Building Automation System workstation). The BACnet communication module continues to poll
the MAC address parameter during run-time. If the MAC 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. Changing the MAC address may affect the operation of other BACnet devices
on the network.
The allowable range of values for the MAC address is: 0-127. Since the BACnet communication
module is always configured as an MS/TP master, only addresses 0-127 are valid.
If a value greater
than 127 is read from the unit controller, the BACnet communication module defaults to a MAC
address of 127. The MAC address must be unique on the BACnet MS/TP network.
Baud Rate
The baud rate is read from a parameter in the Magnitude Chiller Unit Controller during the BACnet
communication module’s initialization phase. The Baud Rate must match the other devices on the same
MS/TP network and requires configuration prior to establishing communications from the unit
controller to the BACnet network. This parameter can only be accessed and configured via the unit
controller OITS panel. It is not accessible from the BACnet network interface (i.e. Building
Automation System workstation).
The BACnet communication module continues to poll the baud rate parameter during run-time. If the
baud rate 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. Baud rates supported are as
follows: 9600, 19200, 38400 (default) and 76800 bps.
BACnet Device Management
The following functions are specific to the BACnet device. These functions are used for maintenance
and testing. A network management tool such as VTS is typically used to issue the network commands.
DeviceCommunicationControl - Disable
The purpose of this command is to reduce network traffic for diagnostic testing of the BACnet network.
When the BACnet communication module receives a network command to Disable communications it
stops communicating information to the network. An optional time may be specified for how long to
