What is OPC Data Acces 2.0

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Thread Starter

Maya

What is OPC data Access 2.0.

Is it a specification or software tool , or data base?
 
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Conrad Fernandez

Maya,

The OPC data access 2.0 is a specification for the communications protocol to be used by OPC objects.
Factory Soft has a downloadable dll file that was written using these specifications. Refer to their web-site http://www.factorysoft.com/Downloads/OPC_components.htm for more information. I use this dll when I reference any OPC objects in my VB applications.

Regards,

Conrad L. Fernandez
 
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Ralph Mackiewicz

A few responses on the OPC 2.0 question went like this:

> OPC is a specification for how software applications talk to each
> other -- information available at http://www.OPCFoundation.org

and

> The OPC data access 2.0 is a specification for the communications
> protocol to be used by OPC objects.

OPC is not a protocol. OPC is an Application Programming Interface (API) specification based on Microsoft's OLE technology. It specifies
an OLE based function call interface by which OPC clients can access data from an OPC server. It does not specify the protocol (OPC does not even require that the OPC server use any protocol) that an OPC server might use to obtain the data. It only specifies the API that a client can use to access the data. Because it is based on OLE, you can distribute calls from an OPC client to an OPC server over a network using Microsoft's DCOM protocol.

There is a new work item by the OPC Foundation under the banner of OPC DX (for data exchange) that might actually be considered a protocol based on XML but details are not yet available.

Regards,

Ralph Mackiewicz
SISCO, Inc.
 
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