Echelon LNS - Manual (Page 49)

LNS Programmer's Guide 35
Network Service Devices
You will notice in Figure 3.3 that each Network object includes a collection of
NetworkServiceDevice objects. Each NetworkServiceDevice object represents a
L ON W ORKS device implemented by LNS for use with that particular network.
Each LNS application uses a Network Service Device to communicate with the
application devices and routers on a L ON W ORKS network when installing, connecting,
managing, and monitoring and controlling the network. Each Network Service Device
contains an LNS network interface. Note that the PC running the LNS Server and
containing the LNS network database is included in the NetworkServiceDevices
collection. The Network Service Device for the LNS Server PC sends all network
management commands required when any application connected to a network installs,
configures and maintains the devices on that network. This is handled transparently by
LNS.
As noted earlier in this chapter, LNS applications can run on the LNS Server PC, or on a
remote PC. Depending on the way a remote application connects to the LNS Server, the
client might use the same Network Service Device as the LNS Server PC within a
network, or it may use its own Network Service Device. For more information on this,
and for an overview the various client types you can use with LNS, and how each one
connects to the LNS Server, see LNS Clients on page 37.
Separate Network Service Devices are defined for each network, even if they are both
associated with the same application. For example, if a single application has two
networks open, each network will contain a separate NetworkServiceDevice object
representing the application’s Network Service Device on that network. All LNS
applications running on the LNS Server PC will use the same NetworkServiceDevice
object within each separate network. Each Network Service Device has its own LonTalk
address, and may have network variables and monitor sets defined on it to support
monitoring and control operations.
Network Interfaces
Each Network Service Device uses a network interface. A network interface (also called a
network services interface, or NSI) is the device that connects the Network Service
Device to the L ON W ORKS network. LNS network interfaces also provide the physical
connection to the network and the messaging connection to the LNS Server. They route
service requests to the LNS Server and other LNS network interfaces (if multiple
Network Service Devices are connected to the network) and coordinate with the LNS
Server to manage transactions.
For more information on network interfaces, and for a list of the various network
interface devices that are commonly used with LNS, see Chapter 11, LNS Network
Interface Devices.