Echelon LNS DDE Server - Manual (Page 14)

That is, the application can observe the values of network variables, configuration
properties, and application and foreign frame messages, and can change the values
of them to affect the operation of the network(s). The LNS DDE Server uses the
naming, addressing, and timing information stored in an LNS Server by a network
tool such as the LonMaker Integration Tool.
There are many tools available for installing L ON W ORKS networks. Some of these
are legacy tools that are not LNS compatible. However, the LNS DDE Server
requires that the network installation be completed using an LNS installation tool. If
you have a network that was installed with a network tool that was not based on
LNS, you can automatically convert the network to LNS using the LonMaker
Integration Tool, release 3.0 or later.
The Role of the LNS Network Interface
An LNS network interface (also called a network adapter, network services interface,
or NSI) is a hardware component with an associated network driver that provides
the physical connection between a L
ON W ORKS network and the PC running the LNS
DDE Server. An LNS network interface is not required if your PC is running as a
remote L
ON
W
ORKS
/IP Remote, LNS/IP remote (i.e. Lightweight), or NetDDE remote
client. For the highest performance for workstation applications on a desktop
attached to a L ON W ORKS /IP channel, you should use an IP network interface card
such as an Ethernet adapter. For the highest performance for workstation
applications on a desktop attached to a L
ON
W
ORKS
channel, you should use a
PCLTA-20 PCI LonTalk Adapter as the LNS network interface (use a PCLTA-10 ISA
LonTalk adapter if you do not have an available PCI slot). If you are using powerline
products or an SMX transceiver, you can use the PCLTA-20/SMX PCI card. If you
have a laptop attached to a L ON W ORKS channel with a PCMCIA-compatible PC Card
slot, you can use the PCC-10 PC Card interface. For connecting to a L ON W ORKS
channel remotely via phone lines and a pair of modems, or if your host does not have
an available ISA, PCI, PC Card slot, you can use a SLTA-10 Serial LonTalk Adapter.
All PC-compatible LNS network interfaces are functionally equivalent; so your DDE
client application does not need to be modified when the LNS network interface
hardware changes. If you are not using a PCLTA-10, PCLTA-20, PCNSI, PCC-10,
SLTA-10, of IP network interface card, check your documentation to see if your
network interface is LNS-compatible.
Overview of DDE
Dynamic Data Exchange (DDE) defines a standard way for Microsoft Windows
applications to share information with one another. The following sections provide a
very brief overview of DDE.
When applications share information with each other using DDE, they are said to be
holding a DDE conversation. Each conversation has a well-defined beginning,
middle, and end. To begin a conversation, one application, known as the client, or
destination application, asks another application, known as the server, or source
application, to open a communications channel (this is different than a L
ON W ORKS
channel, which is the physical communications medium used by L ON W ORKS devices).
1-6 LNS DDE Server Overview