Displaying Single Process Alarms Across Multiple Plant Hierarchies and Control Rooms

In SIMATIC PCS 7, an individual CFC chart or block cannot reside in multiple Plant Hierarchy (PH) folders simultaneously because the tag name, WinCC archive path, and default alarm area derive strictly from a 1-to-1 hierarchy path. To display a single process alarm across multiple control rooms without duplicating CFC logic, configure WinCC Area Authorizations so operator stations in both control rooms possess viewing permissions for the originating plant area. Additionally, place a WinCC Group Display object (@PG_GroupDisplay) on the second control room's mimic overview and interconnect its CollectValue property to the tag's hierarchy path.

Plant Hierarchy 1-to-1 Architecture in SIMATIC PCS 7

The SIMATIC PCS 7 Plant Hierarchy (PH) organizes automation objects into logical operational structures reflecting plant layout (e.g., Plant\Area_01\Unit_A\Reactor_1). In PCS 7 engineering, the Plant Hierarchy enforces a strict 1-to-1 relationship: a CFC chart can only be contained within a single hierarchy folder.

When AS-OS compilation executes, the system generates the WinCC tag name by concatenating hierarchy folder names and block names. Furthermore, WinCC automatically assigns the alarm to the OS Area corresponding to the highest configured hierarchy level. Duplicating CFC charts into different hierarchy folders merely to duplicate alarms is prohibited, as it doubles Process Object (PO) license consumption, strains controller CPU cycles, and risks logic synchronization discrepancies.

Methods for Multi-Control Room Alarm Distribution

When plant requirements dictate that an alarm originating in Area A must be visible and acknowledgeable in Area B (or across two separate control rooms staffed by different operating teams), three standard architectural mechanisms exist:

WinCC User Administrator and Area Permissions: In WinCC User Administrator, assign the OS Clients or operator logins in Control Room B authorization to view the OS Area of Control Room A. The WinCC Alarm Control automatically aggregates and displays alarms from all authorized areas in the top overview line and alarm pages.
WinCC Group Display (@PG_GroupDisplay) Interconnection: In the Graphics Designer screen representing Control Room B, insert a Group Display object. Bind its .CollectValue property to the tag or hierarchy node in Area A. When an alarm occurs, the group display changes color and flashes in Control Room B.
Common Overview Alarm Windows with Custom SQL Filters: Configure a dedicated 'Common Utility Alarms' window in WinCC Alarm Control with custom filter criteria matching specific message numbers or process tags.

Comparison of Multi-Area Alarm Integration Strategies

The table below compares engineering strategies for presenting alarms across multiple plant hierarchy areas:

StrategyConfiguration LayerLicensing ImpactEngineering Overhead & Operational ResultWinCC Area Authorizations (Recommended)OS User Administrator / Area assignmentZero PO impactOptimal: Operators see native alarms in overview banner and alarm lists based on role privileges.WinCC Group Display ObjectWinCC Graphics DesignerZero PO impactHigh visual feedback: Flashes on mimic overview screens, driving operator navigation to origin.Cross-Chart Logic Mirroring (MonDiS)AS Controller (CFC interconnection)Consumes 1 AS/OS PONot Recommended for Alarms: Duplicates alarm messages; risks double-acknowledgment confusion.CFC Chart DuplicationAS ControllerConsumes duplicate POsProhibited: Violates single-source truth; causes logic divergence and license waste.

Step-by-Step Configuration: WinCC Group Displays and Area Permissions

Configure WinCC Area Privileges:
- In WinCC Explorer on the OS Server, open User Administrator.
- Select the user group or operator role assigned to Control Room B.
- In the Area Authorizations matrix, grant Enable privileges for both Area A and Area B.
Insert Group Display in Control Room B Mimic:
- Open WinCC Graphics Designer and open the main overview screen for Control Room B.
- From the Object Palette (Smart Objects), drag a Group Display (@PG_GroupDisplay) onto the canvas.
Bind Group Value Property:
- Open the Object Properties of the Group Display.
- Navigate to Properties -> Geometry -> Group Value (or CollectValue).
- Connect the dynamic tag to the hierarchy area tag of Area A (e.g., Area_A/@AreaState or specific block tag Area_A/Chart/Motor.EventState).
Configure Picture Tree Navigation Link:
- In the Event tab of the Group Display, assign a mouse-click C-action or standard function (SSMOpenTopFieldFix) to open the Area A mimic screen when operators click the flashing alarm icon.
Save and Deploy: Save graphics, run the OS Project Editor, and download changes to OS Clients.

Verification

Verify alarm behavior across both control rooms through the following tests:
1. Trigger an alarm in Area A (e.g., high limit on an analog sensor).
2. In Control Room A: confirm that the alarm appears in the top alarm banner and alarm list.
3. In Control Room B: confirm that the alarm appears in the incoming alarm list and that the Group Display on the overview screen flashes with the correct alarm class color (e.g., red for high priority).
4. Acknowledge the alarm from either control room (if authorized): confirm that the flashing state transitions to steady acknowledgment synchronously across both stations.

Limitations and Operational Precautions

Carefully manage alarm acknowledgment rights. If operators in Control Room B are permitted to acknowledge alarms originating in Control Room A, operational responsibility must be governed by plant standard operating procedures (SOP). Furthermore, never attempt to bypass Plant Hierarchy integrity by creating duplicate WinCC raw archive tags in SQL Server, as this desynchronizes the WinCC Picture Tree Manager.