Echelon ISI - Manual (Page 4)

ISI Programmer’s Guide 2
Overview
Control networks consist of intelligent devices like switches, thermostats, pumps,
motors, valves, controllers, and a variety of other sensors and actuators that
communicate with each other to provide distributed monitoring and control. A
control network may be a small, simple network consisting of a few devices; may
be a large network in a building, factory, or ship consisting of tens of thousands
of devices; or may even be a very large regional network consisting of millions of
devices. In every case, the devices in the network must be configured to become
part of a common network, and to exchange data amongst themselves. The
process of configuring devices in a control network to establish communication
among the devices is called
network installation .
Networks can be categorized by the method used to perform network installation.
The two categories of networks are
managed networks and self-installed
networks. A managed network is a network where a shared network
management server is used to perform network installation. A user typically
uses a tool to interact with the server and define how the devices in the network
should be configured and how they should communicate. Such a tool is called a
network management tool . For example, Echelon’s LonMaker ® Integration Tool
is a network management tool that uses a network management server called the
LNS ® Server to install devices in a network. Although a network management
tool and a server are used to initially establish network communication, they
need not be present all the time for the network to function. The network
management tool and server are only required whenever changes are made to the
network’s configuration.
In a managed network, the network management tool and server allocate various
network resources, such as device and data point addresses. The network
management server is also aware of the network topology, and can configure
devices for optimum performance within the constraints of the topology.
The alternative to a managed network is a self-installed network. There is no
central tool or server that manages all of the network configuration in a self-
installed network. Instead, each device contains code that replaces parts of the
network management server’s functionality, resulting in a network that no
longer requires a special tool or server to establish network communication or to
change the configuration of the network.
Devices in a self-installed network cannot rely on a network management server
to coordinate their configuration. Since each device is responsible for its own
configuration, a common standard is required to ensure that devices configure
themselves in a compatible way. The standard protocol for performing self-
installation in L ON W ORKS networks is called the L
ON
W
ORKS
Interoperable Self-
Installation (ISI) Protocol . The ISI protocol can be used for networks of up to 200
devices that meet topology and connection constraints described in this guide.
Larger or more complex networks must either be installed as managed networks,
or must be partitioned into multiple smaller subsystems, where each subnetwork
has no more than 200 devices and meets the ISI topology and connection
constraints. Devices that conform to the L ON W ORKS ISI protocol are called ISI
devices .