Echelon LNS - Manual (Page 54)

LNS Programmer's Guide 40
connection to the LNS Server and the data monitoring and control are through the
TCP/IP connection.
On some PCs, if an established TCP/IP connection is idle for some time, the PC enters a
power-save mode that causes TCP/IP disconnection. The LNS Server treats this as it
would any other disconnection. Once the LNS Server detects the disconnection, the client
application must reestablish its connection to the LNS Server by closing the System and
Network, and then reacquiring and reopening them. Similarly, all other LNS object
references that the LNS application holds in scope must be released and reacquired from
the LNS Server. To avoid going into power save mode unintentionally, disable the power
saver mode on the LNS Server PC and the PC running your Lightweight client
application.
All remote Lightweight client applications use the same NetworkServiceDevice object
that the LNS Server PC uses, and that the local client applications use for a given
network. Therefore, any network variables, connections, and monitor sets defined on that
Network Service Device are available to both Local and Lightweight clients.
Full Client Applications
Full Client applications run on a different PC than the LNS Server and the LNS
database, as shown in Figure 3.6.
LONWORKS Network
LNS Serv er PC
(Host PC)
LNS Application PC
(Remote PC)
LonWorks
Dev ices
L ON W ORKS Network
L ON W ORKS
Device
L ON W ORKS
Device
L ON W ORKS
Device
L ON W ORKS
Device
L ON W ORKS
Device
Figure 3.6 Network Communication as a Full Client
Each Full client PC contains a network interface it uses to connect to the L ON W ORKS
channel, and communicate with the L ON W ORKS network and LNS Server. For
descriptions of the network interfaces you can use with LNS, see Chapter 11, LNS
Network Interfaces.
In the case of a communication problem between the LNS Server and a Full Client
application, the LNS Server will retry the connection for more than a minute before
timing out and determining that the client is disconnected. From the point of view of the
Full Client application, a communication problem that results in disconnection will
appear to be an unusually long LNS service that ultimately returns the LCA:#120
lcaErrNoConnectionToServer exception.
Each remote Full Clients use a NetworkServiceDevice object defined for shared use
by it and all the other remote Full Clients on the same PC connected to the network.
They do not share the Network Service Device used by Local Client applications,