Integrating Third-Party and OEM WinCC Projects into SIMATIC PCS 7 OS - Multi-Client Architecture vs Tag Database Merging

Third-party or OEM WinCC projects cannot be directly merged into an existing SIMATIC PCS 7 OS Server project database. In PCS 7, the OS database is deterministically generated and managed by the AS-OS Engineering Compiler based on the Step 7 Multiproject hierarchy. Compiling the PCS 7 OS with 'Entire compile' will purge any manually imported tags residing in the S7 Named Connection. The architecturally sound, supported Siemens solution is to configure a Multi-Client architecture: maintain the OEM WinCC station as an independent WinCC Server, generate its Server Data package (*.pck), and assign this package to the PCS 7 OS Clients. This enables unified operator visualization across both systems without interfering with PCS 7 automated compilation pipelines or risking database corruption.

Architectural Incompatibility: Standalone WinCC vs Managed PCS 7 OS Projects

In industrial process plants, engineers frequently encounter package units, vendor skids (such as water treatment systems, chillers, or packaging lines) engineered with standalone Siemens Step 7 and standard WinCC. A common requirement is to integrate these vendor applications into the central SIMATIC PCS 7 plant supervisory control system (e.g., a redundant PCS 7 OS Server pair with multiple OS Clients).

Engineers must recognize that WinCC project databases cannot be unified or merged into a single database file. A PCS 7 OS project is not merely a WinCC project; it is an integrated sub-component of a Step 7 Multiproject. Its tag structure, alarm definitions, archive tags, and picture hierarchy are automatically synchronized from the AS CFC charts and SFC sequences via the AS-OS Compiler (AS-OS Engineering).

Attempting to manually copy tags, scripts, and alarms from a standalone WinCC project into a PCS 7 OS project breaks the strict relational integrity enforced by the PCS 7 engineering toolchain.

Consequences of Compiling an OS Project with Manually Imported Tags

When engineers attempt to manually import vendor tags into a PCS 7 OS project (e.g., using WinCC Configuration Studio or Tag Export/Import), the location where those tags are defined determines whether they survive OS compilation:

Tags Assigned to S7 Named Connections: If third-party tags are placed under the S7 Named Connection generated by the PCS 7 AS-OS compiler, triggering an 'Entire compile' or 'Changes compile' in SIMATIC Manager will cause the compiler to reconcile the OS database against the CFC symbol database. Any tag not originating from a CFC block marked with { S7_m_c := 'true' } will be classified as obsolete and permanently deleted during compilation.
Tags Assigned to Independent Communication Drivers: If vendor tags are created under a separate communication channel (e.g., Industrial Ethernet > TCP/IP or OPC Channel) separate from the PCS 7 Named Connection, the AS-OS compiler will ignore that driver channel, leaving the tags intact. However, system messages, standard PCS 7 faceplates, and picture navigation trees cannot automatically bind to these raw tags without manual engineering.
Picture Overwrite Risks: If vendor graphic files (*.pdl) have identical filenames to standard PCS 7 template pictures (such as @screen.pdl, @overview1.pdl), copying them directly into the GraCS folder will corrupt the PCS 7 runtime interface.

Supported Integration Methods: Multi-Client, OPC, and Siemens DBA

Siemens provides three supported engineering architectures to integrate third-party WinCC or non-PCS 7 automation stations into a PCS 7 environment:

Multi-Client Architecture (Recommended):
The vendor WinCC project remains an independent WinCC Server (single station or redundant server). Its OS Server Data package (*.pck) is generated and loaded into the PCS 7 OS Clients. The PCS 7 OS Client acts as a multi-client, concurrently communicating with both the primary PCS 7 OS Servers and the vendor WinCC Server. The operator views screens from both systems within a unified multi-screen layout.
Siemens DBA (Database Automation) Integration:
For non-PCS 7 controllers (S7-300, S7-1500, or third-party PLCs), the vendor controller is integrated using Siemens DBA. DBA imports the controller tags and automatically generates PCS 7-compliant OS tags, alarm messages, and block icons in the PCS 7 OS, allowing full AS-OS compile compatibility.
OPC DA / OPC UA Integration:
The vendor system acts as an OPC Server, and the PCS 7 OS Server connects as an OPC Client. Tags are maintained in an isolated OPC channel that the AS-OS compiler never touches.

Comparative Architecture Matrix: WinCC Integration Methods in PCS 7

The following table evaluates the four integration approaches for incorporating external WinCC applications into a PCS 7 plant environment:

Integration ApproachAS-OS Compile SafetyAlarm System IntegrationFaceplate CompatibilityEngineering EffortSoftware License ImpactDirect Database MergeUnsafe (Tags Deleted on Compile)High Risk of CollisionIncompatibleExtremely HighRisk of Invalid PO CountMulti-Client Architecture100% Safe (Isolated Databases)Unified Alarm Display (Multi-Server)Native Vendor FaceplatesLow (Server Data Link)Requires Server/Client RT LicensesSiemens DBA Tool100% Safe (Managed by DBA)Fully Integrated PCS 7 AlarmsStandard PCS 7 APL / DBA FaceplatesModerate (DBA Mapping)Consumes PCS 7 OS RT POsOPC DA / OPC UA ChannelSafe (Independent Driver Channel)Basic (Requires EventRaw / Custom)Requires Custom User GraphicsModerate (Tag Linkage)OPC Server / Tag Licenses

Step-by-Step Procedure to Integrate an OEM WinCC Station via Server Data Package

To safely integrate an independent WinCC station into a PCS 7 plant using the Multi-Client approach, follow these steps:

Verify Software Version Compatibility:
- Ensure the vendor WinCC version is compatible with the PCS 7 OS Client version (e.g., PCS 7 V8.0 SP2 utilizes WinCC V7.2; PCS 7 V8.2 utilizes WinCC V7.4; PCS 7 V9.0 utilizes WinCC V7.4 SP1). Discrepancies may require upgrading the vendor WinCC project.
Configure Network and Simatic Shell:
- Connect the vendor WinCC Server to the PCS 7 Terminal Bus.
- Open Simatic Shell on all participating stations (PCS 7 OS Clients, PCS 7 OS Servers, OEM WinCC Server).
- Verify that all stations can resolve each other by NetBIOS/DNS name and appear in Simatic Shell without blue question mark icons.
Generate Server Data on OEM WinCC Server:
- Open the OEM WinCC project in WinCC Explorer.
- Right-click Server Data in the project tree and select Create...
- WinCC generates the package file <ProjectName>.pck in the project directory under \Packages\.
Import Server Data on PCS 7 OS Clients:
- Open the PCS 7 Multiproject in SIMATIC Manager on the ES.
- Open the OS Client project in WinCC Explorer.
- Right-click Server Data -> Assign... -> browse to the shared \Packages\ folder on the OEM WinCC Server.
- Select the package file and load it.
Configure Picture Navigation and Runtime Calling:
- In the PCS 7 OS Client WinCC Explorer, configure picture navigation (via Picture Tree Manager or customized buttons) to call pictures from the imported package using the standard server prefix syntax: VendorServer::PictureName.pdl.
Deploy Changes to OS Clients:
- Perform an OS Client download or project update from SIMATIC Manager.
- Activate the OS Clients and verify seamless switching between PCS 7 plant areas and OEM skid graphics.

Commercial Accuracy Disclaimer

Commercial Accuracy Disclaimer: Software order numbers (MLFBs), package structures, and hardware capacity prerequisites vary across PCS 7 versions and hardware platforms. System integrators must confirm exact software entitlements and licensing requirements against the official Siemens Catalog CA 01 and obtain an authorized Siemens distributor quotation prior to purchasing.

When implementing Multi-Client architectures, each server station (both the PCS 7 OS Server and the standalone vendor WinCC Server) requires independent WinCC Server Runtime licenses and appropriate Process Object (PO) or Tag tier licenses. Clients accessing multiple servers do not require redundant client licenses for each server, but terminal bus networking and CALs (Client Access Licenses) must be verified.

Verification

Verify the integration through the following systematic checks:

On the Engineering Station, perform an Entire Compile of the PCS 7 OS. Confirm that the compilation finishes without warnings or errors regarding missing or deleted vendor tags.
Open the PCS 7 OS Client in Runtime. Verify that connection status icons indicate active communication with both the PCS 7 OS Servers and the OEM WinCC Server.
Navigate to an OEM skid screen. Verify that dynamic process tags update with valid green quality codes (0x80).
Trigger a process alarm on the vendor skid controller. Confirm that the alarm appears in the unified PCS 7 OS Client alarm banner and shows the correct server prefix origin.
Acknowledge the alarm from the PCS 7 OS Client and ensure the acknowledgment state synchronizes back to the vendor WinCC Server.

Limitations and Operational Precautions

Version Locking: Multi-Client communication requires strict WinCC version alignment. An OS Client cannot reliably load server data from a WinCC Server running an older or incompatible major release without compatibility packs.
Network Segmentation: In plants with strict ISA-95/Purdue model network segregation, placing vendor skids directly on the PCS 7 Terminal Bus requires careful firewall and routing management to prevent broadcast storming or IP conflicts.
Redundancy Synchronization: If the vendor WinCC server is redundant, ensure both redundant package names are properly imported into the client, allowing automatic failover without operator intervention.

Engineer FAQ

Can I copy vendor PDL files directly into the PCS 7 OS project's GraCS folder?

Yes, graphic files (*.pdl) can be copied into the GraCS folder of the PCS 7 OS without being deleted during an OS compile. However, you must ensure their filenames do not conflict with system templates (e.g., @*.pdl), and any dynamic tag connections inside the pictures must point to valid existing tags.

What happens to manually created WinCC internal tags during an OS compile?

WinCC internal tags are completely safe during both Changes Compile and Entire Compile. The AS-OS Engineering compiler only manages external communication tags bound to S7 Named Connections.

Can an S7-300 PLC be integrated directly into a PCS 7 OS Server?

Yes. You can create a standard S7 Protocol Suite (Industrial Ethernet or TCP/IP) connection directly inside WinCC Tag Management to an S7-300 CPU. The AS-OS compiler will ignore this manual connection during compiles.

Why can't two WinCC SQL databases simply be merged into one?

WinCC utilizes proprietary Microsoft SQL Server database schemas where object IDs, alarm numbers, tag IDs, and archive segment structures are sequentially indexed. Merging two databases causes severe primary key and foreign key collisions that irreparably destroy database integrity.

Does the OS Import function in SIMATIC Manager merge the projects?

No. The 'Options > OS Import' function creates a separate OS station inside the project tree representing the external WinCC project; it does not merge the graphics, scripts, or tags into an existing PCS 7 OS Server.