Echelon LNS DDE Server - Manual (Page 15)

Once a conversation is established, the client can send and receive data from the
server on the DDE channel. For example, an Excel spreadsheet (the client) may ask
the LNS DDE Server (the server) for the current fuel consumption from a flow sensor
for use in an automated billing system. Or, an InTouch operator interface (the
client) may tell the LNS DDE Server (the server) to change the state of a valve in a
L
ON W ORKS network in response to a request issued by the operator. The client
application is always the application that establishes the conversation, irrespective
of which way the data actually flows. The LNS DDE Server is always a server
application.
Types of DDE Services
A client uses different DDE services during the course of a DDE conversation. The
DDE services discussed in this manual are the following:
Initiate
A request to start a new DDE conversation.
Terminate A request to end a DDE conversation.
Request A one-time request by the client for a specific piece of data
from the server. This is also referred to as a Cold or
Manual Link. The server does not notify the client of
changes; the server only sends the item's value when
requested by the client.
Advise A request by the client for on-going updates for a specific
piece of data from the server. There are two types of Advise
requests.
Hot or
Automatic Whenever the value of the item changes, the
server automatically sends the client the
new value.
Warm or
Notify Whenever the value of the item changes, the
server sends the client notification that the
value has changed. If interested, the client
requests the new value from the server.
Note: The LNS DDE Server does not
support warm (notify) links.
Poke A request from the client to the server to change the value
of a specific piece of data.
Execute A request from the client to the server to perform a
command.
Execute Commands
The LNS DDE Server provides the following commands via the DDE execute service.
These commands are not case sensitive.
LNS DDE Server User's Guide 1-7