But the Value cannot be Variant.Empty for mandatory properties.

However, the "" rule does not apply if the description of the property makes it clear that "" is not a valid value:

SourceName provides a description of the source of the Event. This could be the string-part of the DisplayName of the Event source using the default locale of the server, if the Event is specific to a Node, or some server-specific notation.

(i.e. "" is not a description)

Clients should be designed defensively to deal with misbehaving Servers but that does not make the server right.

Is it allowed, according to the specifications, to set the value on a mandatory property, in an event, to null. 

For example:

Assuming an event of EventType BaseEventType.

Is it allowed for an OPC UA server to set, for example, property SourceName to null in the event?

If it is, is it the same for any mandatory property in any EventType? 

Should an OPC UA client be able to take that into account?

Thanks

https://mantis.opcfoundation.o.....default=no

https://mantis.opcfoundation.o.....default=no

Section 9.1 General of OPC 10000-3; OPC Unified Architecture Part 3 :Address Space Model; Release 1.05.06; 2025-10-22 starts with "The remainder of 8.61 defines EventTypes." Section 8.61 is about CurrentyUnitType.

See also section 4.1, first paragraph, last sentence: "Standard ReferenceTypes, DataTypes and EventTypes are defined in Clauses 7 to 8.61."

As well section 4.7.2 EventTypes, last paragraph, first sentence: "Standard EventTypes are described in Clause 8.61."

There seem to be a typo, an incorrect or undefined reference.

Thanks and regards

I'm working through the spec, currently OPC 10000-3; OPC Unified Architecture Part 3 :Address Space Model; Release 1.05.06; 2025-10-22.

Annex B, section B 3.4 Object and ObjectType is short with the follwoing text: "Objects and ObjectTypes are shown in Figure B.8."

The description of the figure is given, but the figure itself is missing.

At least the necessary information is shown in figure B.7. Figure B.7 is a bit cluttered and makes it hard to make out specific details.

Best regards

happy to hear that you started working with the CTT to test your product. I assume your problem is something very basic like that the setting has not been stored in the configuration yet, since you haven't clicked on "Apply". You'll find the "Apply" button at the bottom of the settings dialog. Once you applied the configuration change with the endpoint URL the connection should be working fine.

If you are then still facing issues. Please let me know.

Regards,
Alexander Allmendinger

I'm trying to start a project om CTT, but when I add my Server URL i only receive back No endpoints discovered. The same server works well via UAExpert. Any possible causes and solutions?

https://opcfoundation.org/deve.....urce-code/

I am not aware anything available today.

I am working on a project that requires me to implement an OPC Xi server to maintain compatibility with a legacy client.

I have been searching for the original OPC Xi Reference Implementation, SDK, or Compliance Test Tool binaries, but as these were deprecated years ago, I am unable to find any functional links or repositories.

Does anyone happen to have an archive of these legacy OPC Foundation OPC Xi resources (circa 2010–2012)? Even if the code is outdated, having the reference implementation would be incredibly helpful for debugging my current attempt at a server implementation.

Any leads or pointers on how to actually target this standard would be greatly appreciated.

Thank you for your time and help.

Not every client will look for it but it is required if you are returning exchanging instances over the wire.

Specification is fairly clear:

https://reference.opcfoundatio.....erences%2E

We already tested with UAExpert and with that tool we are able to execute the method call. However according to Siemens the method call executed by Opcenter Execution MOM fails because our custom created 'DataType -> BaseDataType -> Structure -> FieldObject' does not return HasEncoding. This is also confirmed when browsing to FieldObject with UAExpert.

Because we now have internally a discussion in whether or not the problem is on the OPC-UA server side or in Siemens Opcenter Connect MOM I wanted to use the UACTT Lite test tool so that it maybe would confirm the feedback of Siemens that the OPC-UA Server is not compliant to the standard.

Is it possible to also answer my initial question if it is possible to test an OPC-UA method call with UACTT Lite?

Regards,

Erik