OPC连接建立

Question

I am a newbie. I have searched various forums for opc application. It seem they are using US SDKs to create opc client and server application. I have gone through Unified automation SDK and i am sucessful to connect, read and write. But i need to create my own opc application. I wanted to know how to connect opc server and client without using any external SDKs or application. In my first step i want to know the communication packet required to establish the connection in between server and client. I have tried wireshark to see the communication packet but i couldnot figure them out.

I want to make a simple program in c++ to establish connection in between opc client and server and preferrably a opc UA.

I also think that i am doing it wrong way to make opc application. What can be the right step to start working to develop opc client and opc server.

Could you please help me. I have been stuck in this problem for a long time.

Regards, Sika

Answer 1

Starting developping an OPC UA Client/Server has few possibilities :

First is to use one of the Stack provided by OPC Foundation (.NET, Java or C/C++). The 1.02 has just been released this month. Then you will maybe need to port on your platform depending of the language you want to use. The Stack is only the communication part, you will be required to code everything on it (like SessionManager, SubscriptionsManager,...) to send your data through it. You need to be OPC Foundation member ($) to download it.

The second is to try or buy a SDK from a third party : Prosys, Unified Automation, Softing,... You could find them easily on search engine. They give you a nearly ready to go Client/Server interface where you only have to connect with your data. It could cost you a lot of money but save you some time.

The third is to join one of the open source project such as Open OPC UA giving you the possibility to develop your own OPC UA Client/Server with an OpenSource code base.

BTW there is no more forum on the OPC Foundation website. I recommend you to use this website since it starts to have some OPC topics

Answer 2

OPC UA communication packet details can be found in Part 6 of the spec. BTW, specs now are available for registered users too (not paying members). And SDKs are available under GPL license on GitHub.