Configuring Local OpenPCS 7 Testing and OPC Scout Connections on Engineering Stations

Connecting OPC Scout locally to OpenPCS 7 on a single Engineering Station (ES / OS Single Station) fails when the OpenPCS 7 service cannot resolve local COM/DCOM access permissions or when the client targets the wrong ProgID. OpenPCS 7 is architected as an external plant gateway; to test OPC DA data access locally on an ES, connect OPC Scout directly to the native WinCC OPC server ('OPCServer.WinCC') instead of the distributed OpenPCS 7 gateway. If full OpenPCS 7 protocol validation is required, ensure the 'Siemens OpenPCS 7' service is running, grant local DCOM launch/activation rights to user group 'SIMATIC HMI', and point OPC Scout to ProgID 'OpenPCS7.OPC.DA'.

OpenPCS 7 Architecture vs Native WinCC OPC Server

In SIMATIC PCS 7, OPC interfaces expose plant automation data to third-party clients (such as historians, MES, and manufacturing dashboards). Engineers frequently encounter confusion between two distinct OPC server layers available in the architecture:

Native WinCC OPC DA Server (OPCServer.WinCC): Shipped standard with WinCC OS, this server runs as an in-process COM component directly accessing the active WinCC DataManager. It provides direct, high-performance data access to all tags in the active OS project.
OpenPCS 7 Gateway (OpenPCS7.OPC.DA / SPOSA): A specialized, distributed integration gateway designed to run on a dedicated server PC. OpenPCS 7 connects across the terminal bus to redundant OS Servers, automatically managing server failover, AS-level direct queries, and OPC HDA / OPC A&E buffering.

Attempting to test OpenPCS 7 locally on an Engineering Station where the ES, OS, and client software reside on the same PC frequently conflicts with DCOM authentication and loopback interface routing.

Root Cause Analysis - DCOM and Station Configuration on Local ES

When an engineer inserts the SPOSA (Single Point of System Access / OpenPCS 7 Station) application into the Station Configuration Editor on a single ES laptop, OPC Scout often reports 'Cannot connect to server' or fails to browse tags:
- Local Loopback and DCOM Identity: OpenPCS 7 COM services default to The Launching User or The Interactive User. Over a local loopback connection, Windows DCOM rejects cross-application token elevation unless explicit local launch permissions exist.
- Unassigned OpenPCS 7 Project Path: OpenPCS 7 requires a path assignment pointing to the target OS database (*RT.mdf). If the project is running in OS simulation or the path in the OpenPCS 7 configuration dialog is invalid, the server rejects connection requests.
- Wrong Target ProgID: Engineers often configure OPC Scout to target OPC.SimaticNET (which is intended for direct AS S7 communication via SIMATIC NET) instead of OpenPCS7.OPC.DA or OPCServer.WinCC.

Comparison of OPC DA Connection Interfaces on SIMATIC PCS 7 Stations

The table below contrasts the OPC server ProgIDs available for testing on an Engineering Station:

OPC Server ProgIDUnderlying ComponentLicensing PrerequisitePurpose & RecommendationOPCServer.WinCCNative WinCC Runtime COM ServerIncluded in WinCC RC / RTRecommended for local ES testing: Direct access to all WinCC tags; zero DCOM issues.OpenPCS7.OPC.DAOpenPCS 7 Plant Gateway ServiceDedicated OpenPCS 7 LicenseProduction MES Gateway: Multi-server aggregation; requires active OpenPCS 7 service.OPC.SimaticNETSIMATIC NET PC SoftwareSIMATIC NET S7 LicenseDirect S7 communication to controllers, bypassing WinCC OS entirely.OpenPCS7.OPC.HDAOpenPCS 7 Historical Data AccessOpenPCS 7 LicenseHistorical archive queries from external historians (e.g., OSIsoft PI).OpenPCS7.OPC.AEOpenPCS 7 Alarms & EventsOpenPCS 7 LicenseEvent stream export to plant incident management systems.

Step-by-Step Procedure for Local OPC Testing and DCOM Setup

Confirm WinCC Runtime State: Ensure the WinCC OS project is active in Runtime on the Engineering Station.
Direct Testing via WinCC OPC Server (Fastest Method):
- Launch OPC Scout V10 (located under Siemens Automation -> SIMATIC NET -> OPC Scout).
- Expand Local COM Objects -> Data Access -> OPCServer.WinCC.
- Click Connect: browse the project tag hierarchy, add process tags to the watch view, and verify real-time data updates.
Testing via OpenPCS 7 Gateway (If Protocol Validation Required):
- Open Windows Services (services.msc): verify that Siemens OpenPCS 7 is running.
- Open Component Services (dcomcnfg):
- Navigate to Component Services -> Computers -> My Computer -> DCOM Config.
- Locate OpenPCS7.OPC.DA -> right-click Properties.
- Under Security, verify that SIMATIC HMI and Interactive User possess Local Launch, Local Activation, and Local Access.
Configure OpenPCS 7 Station Path: Open the OpenPCS 7 configuration applet in the Windows Control Panel. Ensure the path points to the active WinCC OS project folder on drive C:.
Connect in OPC Scout: In OPC Scout, connect to OpenPCS7.OPC.DA: browse the system tags and verify cyclic polling.

Verification

Verify OPC communication through the following steps:
1. In OPC Scout, verify that the server status icon turns green indicating active connection.
2. Add a dynamic tag (e.g., analog process value FIC101.PV_Out#Value): verify that values increment with status Good (16#C0).
3. Write a test value to a setpoint tag from OPC Scout: verify that the value updates synchronously in the WinCC faceplate.

Limitations and Operational Precautions

Never deploy OpenPCS 7 on production Operator Clients or OS Single Stations without verifying workstation hardware resources. Heavy third-party OPC DA/HDA polling by external historians can saturate SQL Server database CPU resources; in large plants, always host OpenPCS 7 on a standalone dedicated server hardware platform. Furthermore, OpenPCS 7 requires a dedicated runtime license key (SIMATIC OpenPCS 7) managed via Automation License Manager.