what is the difference between OPC server and DDE server

[kamalice]

hi friends,

Can any one explain me what is the difference between OPC server & DDE server in communication between PLC & SCADA.

For my new project i am using compact logix l32e processor and RSVIEW32. i want to communicate between them.please tell me how can i communicate,

regards,
kamal

 

[RussB]

OPC is OLE for Process Control
OLE is Object Linking & Embedding
DDE is Dynamic Data Exchange

Click the links above for detailed definitions.

 

[danw]

The purpose of OPC generally is to allow interconnection of different brands of field devices (controllers/PLC's) to HMI/SCADA software.

An OPC server (usually a software package on a Windows PC, but sometimes embedded in a field device) is responsible for communicating to the field device (PLC) and getting data that the OPC client asks for from (or to) the field device. The 'driver' for the field device is part of an OPC server.

Software products in the generic category of HMI/SCADA are almost always have (optional) OPC client capability.

OPC clients automatically scan the host PC and the network for OPC servers and connect to them.

OPC (before the latest UA version) used a Windows component known as DCOM (distributed oomponent object model) to communicate from OPC server to OPC client.

DDE is an older form of Windows based communication.

OPC was an outgrowth of the lack of DDE robustness.

OPC servers are licensed software.
OPC clients are licensed software options in HMI/SCADA software
OPC test clients are generally free for purposes of testing OPC server configurations, but are limited to test type tasks.

> compact logix l32e processor and RSVIEW32
I'm not an Allen Bradley guy, but I recognize these as A-B model names.

You can probably get these devices communicating without using OPC, because they are both A-B products, but you'll need an A-B guy to tell you what is needed to do so.

 

[Ken Roach]

I *was* an A-B guy, but the tattoo is fading.

RSView32 requires an OPC Server to communicate with a ControlLogix or CompactLogix controller.

The most popular OPC Server for Logix-family controllers is the one every RSLogix 5000 user already has installed: RSLinx Classic.

You need a licensed edition of RSLinx Classic; OEM Single Node, OEM, or Gateway.

RSLinx Classic Lite does not support OPC, and therefore will not work with RSView32 and CompactLogix.

The configuration of an OPC Topic in RSLinx and an OPC Node in RSView32 is very well documented in the Online Help and the User Manuals.

 

[The Plc Kid]

Ken

Is this why we have Linx Enterprise now with logix and FT View ME /SE ?

Does Linx Enterprise take the place of having to use the OPC option in Linx OEM,Gateway,Etc?

When RS View 32 came out they did not have linx enterprise so is that why it used OPC in standard Linx?

 

[rdrast]

Linx Enterprise isn't actually an OPC server at all. It is just a Logix optimized communications platform that integrates into FactoryTalk. It is configurable through Studio, or the FT Admin console, and has no built in configuration interface like Linx classic.

It also supports redundancy and FTA&E alarms and events unlike Linx classic. Enterprise doesn't communicate to client programs through OPC, it maps it's data directly into the client apps.

It is also another huge piece of bloatware and registry clogging garbage.

 

[sarathgosh]

sir,
i instaled rslinx classic lite and rslinx enter prize.y talk view scada
also using factor
yet i cant communicate with scada.
can u give me a solution?