OPC UA Alert Texts

WinCC OA OPC UA Alert Texts support multilingual functionality and customization through special locales and global text modifications.

Locales mul and qst

The OPC UA specification supports multilingual texts using the special locales mul (multilingual) and qst (qualified string text). For more information, see the OPC UA specification, part 3, section 8.5.

If an OPC UA Client connects using one of these locales, the WinCC OA OPC UA Server sends the alert texts using the corresponding special representation.

Configuration of qst substitution values:

For defining the qst substitution values, the configuration entry qstAddValue must be defined. The specified parameter _add_value must be set with a JSON string in the following format:

{
  "key1": "text1",
  "key2": ["t1", "t2"]
}
Tip:
Each key can contain either a single string value or an array of string values.

Result of qst configuration:

Setting this value on an alert results in the following qst alert message in UA Expert:

Figure 1. UA Expert Qst Alert Display
Shows the structured display of a qst alert in UA Expert with substitution keys and values

Substitution with normal locales:

If a client connects using a normal locale like en (English) or de (German), the WinCC OA OPC UA Server replaces the alert text automatically. This allows older clients to also benefit from the substitution feature:

Figure 2. UA Expert Alert with Substitution
Shows an alert in UA Expert where placeholders have been replaced with actual values
Important:
Automatic substitution only works when the corresponding substitution values are correctly configured.

Global Alert Text Modifications

Using the following Data Point Elements (DPEs), global prefixes and postfixes can be defined for all alert texts of the OPC UA Server:

_OPCUAPvssServer.Config.AlertTextPrefix
Defines a text that is prepended to every alert message.
_OPCUAPvssServer.Config.AlertTextPostfix
Defines a text that is appended to every alert message.
Note:
These settings affect all alert messages of the OPC UA Server, regardless of the locale used.