In a WinCC Unified project (TIA Portal), I wanted to implement a simple mechanism to detect if a user is logged in. For this purpose, I created a boolean tag called UserLoggedIn that should be set to TRUE when a user is logged in, and FALSE otherwise. To handle this automatically, I initially configured a scheduled task triggered by a change in the system variable @UserName.

However, the task never seems to trigger. The tag remains FALSE even when a user is clearly logged in. To troubleshoot, I changed the task type to cyclic (every 1 second) and added a script line to display the value of @UserName in TraceView using Trace("Username: " + UserName);.

The issue is that @UserName always appears empty in the TraceView. Surprisingly, when I display @UserName in an IO Field on the HMI screen, it correctly shows the logged-in user's name. This confirms that the variable does contain a value, but for some reason it appears empty when accessed from a script.

This behavior blocks me completely, as I cannot reliably detect user login status from within a script. I’m wondering if access to @UserName is limited in script context (maybe due to execution scope?), or if there’s a better/recommended way to detect user login/logout events in scripts within the Unified environment.

Any help or insight would be greatly appreciated.

my script:
export function Task_Tâche_1_Update() {

 let tag1 = Tags("@UserName");
 let tagValue1 = tag1.Read();
 HMIRuntime.Trace("value of MyTag1: " + tagValue1);
 

 if (tagValue1 !== "") {
   Tags("UserLoggedIn").Write(true);
   HMIRuntime.Trace("Utilisateur connecté: ${username}. Tag 'isUserLoggedIn' mis à VRAI");

   
 } else {
   Tags("UserLoggedIn").Write(false);
   HMIRuntime.Trace("Aucun utilisateur connecté. Tag 'isUserLoggedIn' mis à FAUX.");
 }

}


trace view:
Trace(): value of MyTag1:
ScriptContext: SchedulerScriptContext
Module: /global_modules/ScheduledTasks.js
Function: Task_Tâche_1_Update 

Thank you, it works perfectly.