Configuring WinCC Group Display Hierarchies and Picture Tree Alarm Status Propagation in PCS 7 V7.1

In SIMATIC PCS 7 V7.1 WinCC, when an alarm is triggered by a block (such as an Alarm_8P or custom alarm block) but fails to illuminate the corresponding alarm status icon on higher-level Picture Tree navigation buttons, the root cause is an unconfigured Group Display Hierarchy. For alarms to propagate upward through the area navigation hierarchy, the process picture must contain a Group Display object interconnected to the block's .EventState tag, the OS Project Editor setting 'Create / Update group displays' (CreateCSIG = 1 in Ssm.cfg) must be active, and the Picture Tree hierarchy must be recalculated by compiling the OS with 'Picture Tree' checked or saving the Picture Tree Manager.

Executive Summary

In SIMATIC PCS 7 process control systems, the operator interface relies on a hierarchical alarm overview model implemented via the Picture Tree navigation bar. When an abnormal event occurs on a process transmitter or motor deep within a sub-unit graphic screen, the top-level Picture Tree area overview button must immediately display a flashing red or yellow status icon, enabling the operator to click directly down into the faulted process area. A frequent engineering defect occurs when an engineer inserts a new alarm block (such as Alarm_8P or a custom vendor library block) into a graphic: while the local alarm control inside the picture displays the alarm correctly, the parent Picture Tree navigation buttons show zero alarm status. This technical article details the mechanics of the WinCC Group Display hierarchy, the .EventState tag, and the mandatory OS Project Editor settings required for alarm propagation.

The Group Display Hierarchy Architecture in SIMATIC PCS 7 WinCC

The WinCC Picture Tree implements alarm aggregation through an automated cascading hierarchy:

Level 1 (Field Level): Block icons embedded inside process pictures (*.pdl) contain integrated Group Display graphical objects (@GroupDisplay).
Level 2 (Screen Level): Each picture aggregates the states of all internal group display objects into an internal screen tag (@<Picture_Name>#EventState).
Level 3 (Hierarchy Level): Parent hierarchy buttons in the top-level navigation container evaluate the @EventState tags of all subordinate child pictures, bubbling alarms upward from unit pictures to section pictures and finally to plant area overview buttons.

The Role of the .EventState Tag in Alarm Aggregation

Alarm aggregation depends strictly on the 32-bit .EventState process tag:

Tag Encoding: Every technological block with messaging capability (MonAnL, MotL, EventTs, Alarm_8P) generates an .EventState tag in WinCC Tag Management during OS compilation.
Status Encoding: Specific bits encode active unacknowledged alarm classes (Bit 0 = Alarm High, Bit 1 = Alarm Low, Bit 2 = Warning High, Bit 3 = Warning Low, Bit 16 = Acknowledged status).
Missing Interconnection: If an engineer creates a custom graphic or inserts an alarm control without placing a Group Display object interconnected to the .EventState tag of the alarm block, the screen has no mechanism to collect the alarm status, breaking the upward aggregation chain.

Why Picture Tree Buttons Fail to Reflect Lower-Level Alarms

Three primary engineering oversights break Picture Tree alarm status propagation:

Missing Group Display in the PDL: Placing an Alarm_8P block in CFC generates alarms in the message list, but without a Group Display object in the graphic linked to .EventState, the alarm is invisible to the Picture Tree.
OS Project Editor Setting Disabled: If the option 'Create / Update group displays' is unchecked under the Message Displays tab in the OS Project Editor, the automated script engine does not insert the cascading group display tags into higher-level screens.
Unrecalculated Picture Tree: Modifying graphics or hierarchy structures requires recalculating the internal group display database. If the OS was compiled without the Picture Tree option checked, or if Picture Tree Manager was not saved, the database remains desynchronized.

OS Project Editor Configuration: Create / Update Group Displays (CreateCSIG)

The central switch governing group display inheritance is located in the OS Project Editor:

In WinCC Explorer, double-click OS Project Editor.
Select the Message Displays tab.
Ensure the checkbox 'Create / Update group displays' is checked.
Underlying File Setting: This setting corresponds to the entry CreateCSIG = 1 inside the configuration file ..\SSM\Ssm.cfg.
When active, saving the Picture Tree Manager automatically embeds matching group display objects into higher-level navigation containers.

Step-by-Step Procedure to Restore Picture Tree Alarm Propagation

To restore alarm propagation up to Picture Tree navigation buttons:

Verify Group Display in Graphic:
* Open the target process screen in WinCC Graphics Designer.
* Confirm that a Group Display object (@GroupDisplay) is present.
* In Object Properties under Links, verify that the Group Value property is dynamically linked to the technological block's .EventState tag.
* If the group display should not be visible to operators on the graphic face, set its Display property to No (invisible group displays still participate in hierarchy aggregation).
Enable CreateCSIG in OS Project Editor:
* Open OS Project Editor in WinCC Explorer.
* Navigate to the Message Displays tab and check Create / Update group displays.
* Click OK to apply.
Recalculate Picture Tree Hierarchy:
* Open the Picture Tree Manager editor in WinCC Explorer.
* Click Save and close the editor. (Alternatively, execute an OS Compilation with Picture Tree checked).
Refresh Runtime:
* On active OS runtime stations, press Shift + F5 simultaneously to refresh the screen hierarchy, or restart WinCC Runtime.

Picture Tree and Group Display Troubleshooting Matrix

The following table provides diagnosis and remediation for broken alarm propagation:

SymptomUnderlying CauseVerification CheckRemediation WorkflowAlarm visible in picture, absent in Picture TreeGroup Display not linked to .EventStateCheck Group Display Object Properties in Graphics DesignerLink Group Value to <Block>.EventStateAlarm status appears only in subfolder, not areaCreate / Update group displays disabledCheck Message Displays tab in OS Project EditorEnable checkbox (CreateCSIG = 1) and save Picture TreePicture Tree status does not update after savingWinCC Runtime cached older hierarchyPress Shift + F5 in runtimeRefresh runtime or restart WinCC to load new hierarchyStatus icon shows white question mark.EventState tag disconnected or quality badInspect tag status in WinCC Tag ManagementCompile OS to rebuild tag connectionsCustom library block alarms missing completelyBlock lacks S7_m_c = true attribute in CFCCheck block attributes in STEP 7 editorSet S7_m_c = true, compile CFC and OS

Verification

To verify that alarm status cascades accurately to the top of the Picture Tree:

Trigger Test Alarm: In CFC Test Mode, simulate an alarm state on the target block (e.g. set an analog value above the high alarm limit).
Inspect Process Graphic: In WinCC Runtime, open the target picture. Verify that the local group display displays the red 'A' icon.
Verify Navigation Bar: Look at the top-level Picture Tree area overview buttons. Verify that the parent area button displays the flashing red alarm indicator.
Acknowledge Alarm: Acknowledge the alarm on the WinCC alarm banner. Confirm that the status icon transitions from flashing to steady, and disappears completely once the fault condition clears.

Standard APL Blocks vs Raw Alarm_8P: Design Best Practices

For robust, maintainable PCS 7 alarm engineering:

Avoid Raw Alarm_8P in User Charts: Raw Alarm_8P blocks lack technological faceplates, standard block icons, and automatic hierarchy mapping.
Use Standard APL Monitoring Blocks: Utilize MonDiL (Digital Monitoring) or MonAnL (Analog Monitoring) for process measurements. These blocks come equipped with factory-certified block icons containing built-in group displays.
Use EventTs for Custom Messaging: When custom messages are required without analog values, deploy EventTs (Time-Stamped Event) with an associated block icon to guarantee seamless Picture Tree integration.

Limitations and Operational Precautions

Never manually edit internal @EventState tags or hierarchy scripts in the @screen.pdl template. Customizing standard system scripts risks breaking automated OS compilation during future version updates.

Recalculating the Picture Tree during high-activity plant operations can cause momentary navigation pauses on operator consoles; schedule hierarchy recompilations during calm operating shifts.

Engineer FAQ

Can an invisible group display still propagate alarms to the Picture Tree?

Yes. Setting the Display property of a Group Display to 'No' hides it from operator view while allowing WinCC hierarchy scripts to aggregate its status.

Why must I press Shift + F5 in runtime?

Shift + F5 forces the WinCC Split Screen Manager (SSM) to reload the navigation database and recalculate group display states without restarting runtime.

What does CreateCSIG = 1 in Ssm.cfg do?

It instructs the Picture Tree Manager to automatically create cascading internal group display connections across all hierarchical navigation levels.

Does compiling the OS automatically recalculate the Picture Tree?

Yes, provided the 'Picture Tree' checkbox is checked in the OS Compilation wizard options.

Configuring WinCC Group Display Hierarchies and Picture Tree Alarm Status Propagation in PCS 7 V7.1