Echelon IzoT NodeBuilder - Manual (Page 23)

Introduction to NodeBuilder Device Development and
Network Integration
An IzoT or L ON W ORKS network consists of intelligent devices (such as sensors, actuators, and
controllers) that communicate with each other using a common protocol over one or more
communications channels. Network devices are sometimes called nodes.
Devices may be Neuron hosted or host-based. Neuron hosted devices run a compiled Neuron C
application on a Neuron Chip or Smart Transceiver. You can use the IzoT NodeBuilder tool to
develop, test, and debug Neuron C applications for Neuron hosted devices.
Host-based devices run applications on a processor other than a Neuron Chip or Smart Transceiver.
Host-based devices may run applications written in any language available to the processor. A
host-based device may use a Neuron Chip or Smart Transceiver as a communications processor, or it
may handle both application processing and communications processing on the host processor. The
IzoT NodeBuilder tool supports some of the common tasks occurring in the creation of host-based
devices; however, an additional host-based device development tool is required.
Each device includes one or more processors that implement the LonTalk/IP or the ISO/IEC 14908-1
Control Network Protocol (CNP). Each device also includes a component called a transceiver to
provide its interface to the communications channel.
A device publishes and consumes information as instructed by the application that it is running. The
applications on different devices are not synchronized, and it is possible that multiple devices may all
try to talk at the same time. Meaningful transfer of information between devices on a network,
therefore, requires organization in the form of a set of rules and procedures. These rules and
procedures are the communication protocol, which may be referred to simply as the protocol. The
protocol defines the format of the messages being transmitted between devices and defines the actions
expected when one device sends a message to another. The protocol normally takes the form of
embedded software or firmware code in each device on the network. The CNP
is an open protocol
defined by the ISO/IEC 14908-1 standard (defined nationally in the United States, Europe, and China
by the ANSI/EIA 709.1, EN 14908, and GB/Z 20177 standards, respectively). LonTalk/IP is based on
the ISO/IEC 14908-1 standard, with extensions to use IP as the transport protocol.
Channels
A channel is the physical media between devices upon which the devices communicate. The
LonTalk/IP and CNP protocols are media independent; therefore, numerous types of media can be
used for channels: twisted pair, power line, fiber optics, IP, and radio frequency (RF) to name a few.
Channels are categorized into channel types, and the channel types are characterized by the device
transceiver. Common channel types include TP/FT-10 (ISO/IEC 14908-2 twisted pair free topology
channel) which is also called FT, TP/XF-1250 (high-speed twisted pair channel), PL-20 (ISO/IEC
14908-3 power line channel), FO-20 (ANSI/CEA-709.4 fiber optics channel), and IP-852 (ISO/IEC
14908-4 IP-communication).
Different transceivers may be able to interoperate on the same channel; therefore, each transceiver type
specifies the channel type or types that it supports. The choice of channel type affects transmission
speed and distance as well as the network topology.
The IzoT NodeBuilder tool, IzoT Commissioning Tool, and Neuron Chips support all standard channel
types, but not all Neuron Chips support all transceiver and channel types. Smart Transceivers
combine the transceiver and Neuron core in the same chip, and therefore support the channel types
supported by the integrated transceiver.
Routers
Multiple channels can be connected using routers. Routers are used to manage network message
traffic, extend the physical size of a channel (both length and number of devices attached), and connect
IzoT NodeBuilder User's Guide 9