Echelon LNS DDE Server - Manual (Page 103)

Example 1:
Application
LNSDDE
Topic AppMsg Test.subsystem 1.MT
Item msg_in –t SNVT_count
Example 2:
Application
LNSDDE
Topic AppMsg Test.subsystem 1.MT
Item switch.msg_in
Example 3:
Application
LNSDDE
Topic AppMsg Test.subsystem 1.MT
Item switch.msg_in.1
See Requesting a One-Time Update in Excel and Requesting a One-Time Update Using
InTouch in Chapter 5, for a description of how to request a one-time update.
Requesting Ongoing Message Updates
To receive ongoing updates, use the same procedure described for receiving ongoing
network variable updates in Chapter 5, except that you must specify the topic and item
as described earlier in this chapter. When you ask the LNS DDE Server to monitor an
application message, it looks in the LNS database to see if it can receive an application
message from the specified device. If the LNS DDE Server cannot receive an
application message from the specified device, the LNS DDE Server refuses to accept
the request from your client (it returns a DDE negative acknowledgement, a NAK).
Like network variables, the LNS DDE Server uses a report by exception strategy by
default; only changes in a message's value are reported. This may be overridden with
the -n switch when the conversation is initiated.
Unlike network variables, the LNS DDE Server can monitor application messages only
if it is bound to the device sending the message or if the monitored device explicitly
addresses messages to the LNS DDE Server host PC.
See Receiving Ongoing Updates with Excel and Receiving Ongoing Updates with
InTouch in Chapter 5, for examples of receiving ongoing updates.
Sending a Message Update
To send an application or foreign frame message, use the same procedure described for
network variable updates in Chapter 5, except that you must specify the topic and item
as described earlier in this chapter.
Example
Here are three examples of what the application, topic, and item might look like when
sending an application message update, assuming a network (AppMsgTest), an
application device (switch), and a subsystem (subsystem1).
LNS DDE Server User's Guide 7-11