Specifications

RSLinx – Training Guide 43
Item: After the Application and Topic are known, your Microsoft Windows application
must provide RSLinx with the specific Item to discuss. To use the example of the
conversing people: if the individual (who) and general topic of conversation are known,
you must determine the exact data you require.
In the case of Excel, we might know we want to talk to RSLinx (Application) about a
PLC-5 at a certain station (Topic) (that is, we want to send data from a PLC-5 to an
Excel spreadsheet).
The last part of the question, Item, determines which specific data table address to
return to your Windows application.
Example:
Application Topic Item
RSLinx PLC5Topic1 C5:0.acc
(RSLinx) (specific PLC) (specific counter value)
Where RSLinx is the application name, PLC5Topic1 is an example topic name, and
C5:0.acc is an example item, in this case a counter accumulator in a PLC-5.
The Application, Topic, and Item are basic parts of all DDE conversations. Each DDE
compatible Windows program has its own unique syntax. The syntax are special
markings, such as ‘ = | and ! . Consult the documentation of your Windows program to
determine the exact procedure and syntax used for DDE conversations.