How-to Register a input to read an OPC UA value

Prerequisites

These steps need to be completed before continuing

• Register an OPC UA server in RS Production

Instructions

Open up the menu: Hardware \ OPC server

Select the OPC server and then click on the Open button

On the left side of the dialog select the: Inputs alternative and the click on the Create button and select OPC server value input

OPC Input address configuration

In order to build the correct address, we need to know some information about the OPC server setup.

An OPC UA tag address is defined by two components:

• Namespace

• Item Identifier

In RS production the complete address is built up by the following definition:

• nsu=[Full namespace name];[identifier type]=[Identifier]

Identifier type

The identifier type can either be of type string or numeric, meaning it defines how the identifier will be stated. this gives either of these two constructs

For string (s):

• nsu=[Full namespace name];s=[Identifier]

  • The identifier is defined by a string/text: s=Engine.Temperature

For numeric (i):

• nsu=[Full namespace name];i=[Identifier]

  • The identifier is given by a numeric id: i=2048

Namespaces

The namespaces are defined in the OPC Server and you can find the namespace array in the Server section in the OPC server definition.

Connect with an external OPC UA Client to the OPC server and browse the definitions.

In the example below the OPC Client, UaExpert is used to browse the Server folder to find the NamespaceArray.

The Namespace array holds all defined namespaces in the OPC server.

At this server, there are five different namespaces defined.

The namespace array contains five positions and each position contains a full namespace, for example at the position with index 4 the namespace definition is:

• http://www.unifiedautomation.com/DemoServer/

That is the complete nsu string so if we start to define an OPC server address that is defined by using index 4 then the OPC Tag address would start with:

• nsu=http://www.unifiedautomation.com/DemoServer/;[Identifier type]=[Identifier]

Item definition

Using the UaExpert client again to browse for a value that we want to register and start listening to in RS Production.

The details of the NodeId state that it is defined in the namespace with index 4 and the identifier is Demo.Dynamic.Scalar.Double.

Use the NamespaceIndex: 4 to check the complete namespace (nsu) using the namespace array:

At index 4 the namespace is: http://www.unifiedautomation.com/DemoServer/

Building the complete address that will be used in RS Production

• nsu=http://www.unifiedautomation.com/DemoServer/;[Identifier type]=[Identifier]

The identifier type is String

• nsu=http://www.unifiedautomation.com/DemoServer/;s=[Identifier]

The Identifier is Demo.Dynamic.Scalar.Double

• nsu=http://www.unifiedautomation.com/DemoServer/;s=Demo.Dynamic.Scalar.Double

This gives the full address (NodeId) to the OPC server tag/item:

• nsu=http://www.unifiedautomation.com/DemoServer/;s=Demo.Dynamic.Scalar.Double

Adding the OPC Value in RS Production

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