DDE/OPC, topic config in rs linx

[rejoe.koshy]

hi,
Can you guys help me out in understanding the function of DDE/OPC , topic config in RSlinx software.

 

[dmargineau]

DDE = Dynamic Data Exchange is a Windows OS feature which enables interprocess communication.
A RSLinx OPC data server which contains established DDE Topics (communications links) will transfer data between the applications at "the ends" of the established DDE Link.(For example, an Excel document data could be written to a CPU data table or the live processor data table values could be retrived into a spreadsheet).

 

[rejoe.koshy]

the difference between DDE & OPC servers are still not clear to me.I have come across these terms in rs view software as well.

 

[dmargineau]

By design, RSLinx is an OPC data server.(OPC = "OLE for Process Control (OPC), which stands for Object Linking and Embedding (OLE) for Process Control, is the original name for a standards specification developed in 1996 by an industrial automation industry task force. The standard specifies the communication of real-time plant data between control devices from different manufacturers"...Wikipedia)
DDE is just one of the means the OPC protocol could be implemented with.(Windows OS feature)
There are various OPC servers which do not use DDE. RSLinx uses it when configured to do so.