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Questions tagged [opc-ua]

The Open Platform Communications (OPC) Unified Architecture (UA), released in 2008, is a platform independent service-oriented architecture that integrates all the functionality of the individual OPC Classic specifications into one extensible framework. Use this tag on questions that concern Open Platform Communications Unified Architecture, in contrast to legacy OLE-based OPC.

The Open Platform Communications (OPC) Unified Architecture (UA), released in 2008, is a platform independent service-oriented architecture that integrates all the functionality of the individual OPC Classic specifications into one extensible framework.

is an interoperability standard that enables the secure and reliable exchange of industrial automation data while remaining cross-platform and vendor neutral. The specification, currently version 1.03, is developed and maintained by the OPC Foundation with the guidance of individual software developers, industry vendors, and end-users. It defines the interface between Clients and Servers, including access to real-time data, monitoring of alarms and events, historical data access, and data modeling.

From: https://projects.eclipse.org/projects/iot.milo

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862 questions
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Difference Between OPC UA and OPC DA?

Please explain what is the Difference Between OPC UA and OPC DA ? In which condition which one should be used, and if any example can be provided for both OPC UA and OPC DA, it would be helpful
tanuj shrivastava
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Alternative to OPC-UA

Is there any decent alternative to OPC-UA as a solution for accessing process data of a system composed of various PLCs? Something that is platform independent and can "speak" with products of different brands ? I've heard of MQTT but it seems to be…
cid
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What is namespace in OPC-UA?

I am novice to OPC Unified Architecture world and I'm studying it from basics. What exactly are namespaces and why it is always appended with NodeID?
Tushar Mane
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OPC UA protocol vs MQTT protocol

I would like to compare OPC UA vs MQTT on basis of the general characteristics of both the protocols such as Overhead (Packets), Security, Information modeling and Reliability. Where can I find some sample data for Overhead, and other…
Azaksai
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What is the significance of "ns=2;s=" in an OPC node path?

I have noticed that all OPC tag Ids are prefixed with ns=2;s=. Some examples of possible NodeId values would be: ns=2;s=AcquisitionTimeRemaining ns=2;s=Status ns=2;s=Time I am wondering what the significance of this prefix is. Research: Someone…
Kyle Williamson
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OPC UA : minimal code that browses the root node of a server

I am using the OPC UA Foundation SDK to develop a small client. What would be the minimal C# code to: Connect to a server Browse the root node Print the immediate children's BrowseNames Quit? I am given the server endpoint (no discovery), security…
Laurent LA RIZZA
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Eclipse Milo, OPC-UA : where to start?

I am entirely new to the OPC-UA world. I need to establish a proof of concept of how to allow our ERP to communicate with PLCs. I am evaluating software that acts as an OPC-UA server (it is working). I found about Milo and got the code working in…
Fred
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How to access arrays?

I have an OPC server running on a milling machine and want to access the names of the tools which are currently available in the machine. I do know that the names of the variables I am looking for…
tfv
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How are disconnects/re-connects handled in Eclipse Milo on the client side?

I am writing an OPC UA client using Eclipse Milo and stumbled over the following question: how does the client handle the loss of connections. For monitoring values I do this using a subscription with the SubscriptionManager: OpcUaClient client =…
ctron
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Is OPC UA the best way of getting data from many Scada systems?

In my company we have many distributed sites and each one uses a singular Scada system vendor (one uses Wincc, other place uses another...) and this systems works with almost the same kind of information. We need to retrieve some general data from…
user1038302
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OPC UA information model

Lets say I have multiple distributed complex machines. Each machine contains of multiple cpmplex devices. Each device has its own OPC UA server to monitore the device components. With an OPC UA client I want to read all the data items of the OPC UA…
CPA
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Understanding OPC-UA Security using Eclipse Milo

I am new to this OPC-UA world and Eclipse Milo. I do not understand how the security works here, Discussing about client-example provided by eclipse-milo I see few properties of security being used to connect to the OPCUA…
aalbatross
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Java OPC-UA Client Eclipse Milo endpoint URL changes to localhost

I am using Java OPC-UA client Eclipse Milo. Whenever I create a session using endpoint URL of server, method UaTcpStackClient.getEndpoints() changes URL to localhost. String endpointUrl = "opc.tcp://10.8.0.104:48809"; EndpointDescription[]…
Harshal Bhavsar
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node opc-ua - how do i discover a variable in a server?

I am learning node opc-ua and have followed the example provided in the GitHub page for the sample_server.js and simple_client.js. In the sample_server I add a variable when constructing the address space of the server such as: //this code is in…
bulho
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Node OPC-UA: Cannot find dataType Definitions

Node v16.14.2 Node-OPC-UA v2.75.0 Hi, I'm currently running into a problem when reading large ExtensionObjects from a S7-1500 with Custom DataTypes. At the first read process of those ExtensionObjects I'm getting a lot of error messages, telling me…
David
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