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Extremely Basic OPC UA question regarding the URL
February 15, 2021
16:43, EET
Forum Posts: 19
Member Since:
June 2, 2019
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The URL of any server begins with opc.tcp://localhost:port.
The initial part opc.tcp, means that OPC UA being an application layer protocol is using TCP/IP for its communication right?
In more technical words, it is like OPC is mapped to TCP for establishing connection ?

The specification says “The URL scheme for endpoints using OPC UA TCP is ‘opc.tcp’.”
Just wanted a bit more clarity.
Extremely sorry as it is very very basic. Still, I wanted to be clear with it.


February 16, 2021
8:54, EET
Matti Siponen

Forum Posts: 92
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February 11, 2020
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Your assumption is correct. The “opc.tcp” at the beginning of the Endpoint URL indicates that TCP/IP is used to communicate with the Server, which is the most commonly used transport protocol in OPC UA Clients and Servers. Similarly OPC UA HTTPS prefixes Endpoints with “opc.https”. There is also “opc.wss” for WebSocket, though that mapping is not commonly supported. OPC UA PubSub communication model also defines mappings such as “opc.udp” for OPC UA UDP and “opc.eth” for OPC UA Ethernet.

In fact, the OPC UA specification is independent of transport protocols and can be mapped to various transport protocols. See Part 6: Mappings for more information on the topic.

February 16, 2021
12:53, EET
Forum Posts: 19
Member Since:
June 2, 2019
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Thank you so much!

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