BAS communication standards - Intelligent Buildings and Building Automation - page 80

Non-Lonworks
Application Layers

LonMark Profiles

Application Layer

Presentation Layer

Session Layer

LonTalk Protocol
(Neuron Chips)

Transport Layer

Network Layer

Link Layer

Physical Layer

Multi-Media Transceivers

Figure 5.3 LonWorks protocol architecture.

5.3.2 Addressing

The addressing algorithm defines how packets are routed from a source
device to one or more destination devices. Packets can be addressed to a sin-
gle device, to any group of devices, or to all devices. To support networks of
two devices to tens of thousands of devices, the LonWorks protocol supports
several types of addresses, from simple physical addresses to addresses that
designate collections of many devices. The LonWorks address types include
the following:

￿ Physical address: Every LonWorks device includes a unique 48-bit identi-
fier called the Neuron ID. The Neuron ID is typically assigned when a
device is manufactured, and does not change during the lifetime of the
device.
￿ Device address: A LonWorks device is assigned a device address when it
is installed into a particular network. Device addresses are used instead
of physical addresses because they support more efficient routing of mes-
sages, and they simplify replace failed devices.
￿ Group address: A group is a logical collection of devices within a domain.
Unlike a subnet, devices are grouped together without regard for their
physical location in the domain.