C135 PCS 7 (PCS7)
6C
6 Cielo Ciencia y Tecnología
·Publicada en C135 PCS 7 (PCS7)

OpenPCS7 Accessing OS Server Data - Resolving Local COM Server Connection Failures in OPC Scout

OpenPCS7 Accessing OS Server Data - Resolving Local COM Server Connection Failures in OPC Scout

When OpenPCS7 is deployed on a dedicated station to bridge SIMATIC PCS 7 OS data to third-party OPC clients, being able to connect to remote servers (Remote Server > OSServer) but failing to connect via 'Local COM Server' in OPC Scout occurs because OpenPCS7 is designed as a multi-tier OPC gateway rather than a standalone SCADA engine. OpenPCS7 must be configured as a dedicated PC Station in the PCS 7 Multiproject, have the OS Server Data package (*.pck) imported and assigned, and be downloaded via NetPro. Furthermore, accessing local COM servers requires proper DCOM identity mapping, matching Windows user credentials in the local SIMATIC HMI and SIMATIC NET groups across both machines, and verifying that the OpenPCS7 station's Windows computer name resolves bidirectionally.

Table of Contents

OpenPCS7 Architecture: Centralized Gateway for OPC DA, HDA, and A&E

In industrial process control, higher-level Manufacturing Execution Systems (MES), Enterprise Resource Planning (ERP) platforms, and plant historians require standardized access to real-time process values, historical data, and alarm journals. Rather than allowing dozens of external OPC clients to bombard the redundant WinCC OS Servers directly—which could saturate server CPU resources and jeopardize critical operator control—Siemens provides OpenPCS7.

OpenPCS7 acts as an isolated, dedicated communication gateway:

  • It connects internally to the PCS 7 OS Servers via the Terminal Bus as a specialized OS client.

  • It exposes standardized external OPC interfaces: OPC DA (Data Access), OPC HDA (Historical Data Access), OPC A&E (Alarms & Events), and OPC UA (Unified Architecture).

  • External third-party clients connect exclusively to the OpenPCS7 station, offloading DCOM and network overhead from the critical control servers.

Understanding OPC Scout: Local COM Server vs Remote Server Navigation

When testing communication using Siemens OPC Scout (or OPC Scout V10), engineers often become confused by the navigation tree:

  • Remote Server > OSServer: Browses the remote WinCC OS Server machine directly over the network via DCOM. If successful, it confirms that basic network connectivity and WinCC OPC services are active on the server.

  • Local COM Server: Connects to the OPC server instances registered locally in the Windows Registry of the machine running OPC Scout (e.g., OPC.SimaticNET, OPCServer.WinCC, or OpenPCS7.OPCServer).

  • If OPC Scout on the OpenPCS7 VM cannot connect to 'Local COM Server', it means the local OpenPCS7 runtime engine has not initialized, its COM GUIDs are unregistered, or the station lacks the OS Server Data package required to know which remote tags exist.

Prerequisites in SIMATIC Manager: The OpenPCS7 PC Station and Server Data

OpenPCS7 cannot function as an unmanaged standalone software installation; it must be engineered within the PCS 7 Multiproject:

  1. SIMATIC PC Station: Insert a new PC Station named identically to the OpenPCS7 machine's Windows computer name (e.g., OPENPCS7_STN).

  2. Hardware Configuration: In HW Config, insert an OpenPCS7 application slot and an IE General network interface.

  3. Server Data Assignment: In SIMATIC Manager, generate Server Data on the OS Server. Right-click the OpenPCS7 station -> Server Data > Assign... and check the packages generated by the OS Servers.

  4. NetPro Compilation and Download: Open NetPro, compile network connections, and download the PC station configuration to the OpenPCS7 machine.

DCOM Security and User Group Permissions across Virtual Machines

When testing OpenPCS7 across virtual machines (VMs) in a workgroup environment, DCOM security is the primary barrier to successful connection:

  • Matching Credentials: The active Windows user account on the OpenPCS7 VM must exist on the OS Server VM with the exact same username and password.

  • Local Security Groups: On both VMs, this user must belong to:

  • SIMATIC HMI
  • SIMATIC NET

  • Administrators

  • DCOM Configuration (dcomcnfg): In Windows Component Services, ensure that Default Access and Launch permissions include SIMATIC HMI and ANONYMOUS LOGON (for remote OPC enumeration).

Comparative Connection Matrix: Direct OS OPC vs OpenPCS7 Gateway

The following table compares direct connection to WinCC OS OPC servers versus routed access via OpenPCS7:

Feature / ParameterDirect WinCC OS OPC ConnectionOpenPCS7 Gateway ArchitectureTarget MachineProduction WinCC OS ServerDedicated OpenPCS7 Gateway ServerImpact on OS Server CPUHigh (Client queries hit production server)Zero (Buffered by OpenPCS7 gateway)Redundancy HandlingClient must implement custom switchoverOpenPCS7 automatically switches between redundant OS serversOPC Standards SupportedOPC DA, OPC A&EOPC DA, OPC HDA, OPC A&E, OPC UANetwork Security BoundaryDirect access to Terminal Bus requiredCan bridge Terminal Bus to Corporate DMZ / MESLicensing RequirementWinCC Open Options / Basic ServerDedicated OpenPCS7 License Key

Step-by-Step Procedure to Configure and Test OpenPCS7 with OPC Scout

Follow this step-by-step procedure to establish local COM server communication in OpenPCS7:

  1. Configure OpenPCS7 PC Station in SIMATIC Manager:
    - Insert a PC Station with computer name matching the OpenPCS7 VM.
    - Add the OpenPCS7 application in HW Config slot 1 and save/compile.
    - Generate Server Data on the OS Server (Server Data > Create...).
    - Assign the package to the OpenPCS7 station.

  2. Download Station Configuration via NetPro:
    - On the OpenPCS7 VM, configure Station Configuration Editor matching the slots.
    - Download the station from NetPro.

  3. Verify Windows Security and Groups:
    - Open Computer Management (compmgmt.msc) on both VMs.
    - Ensure the engineering user is in SIMATIC HMI, SIMATIC NET, and Administrators.
    - Run SimaticSecurityControl.exe to automatically configure firewall rules.

  4. Launch and Test in OPC Scout:
    - Open OPC Scout on the OpenPCS7 VM.
    - Expand Local COM Server.
    - Locate OPC.SimaticNET or OpenPCS7.OPCServer.
    - Double-click to connect. The server transitions to active state.
    - Browse the tag hierarchy and add items to a test group to view live process data.

Verification

Validate OpenPCS7 operational health through these checks:

  1. In OPC Scout under Local COM Server, verify that the connection status displays 'Connected' with a green indicator.
  2. Add active technological tags (e.g., TIC101.PV_Out#Value). Confirm that values update dynamically with quality code 0xC0 (Good).
  3. Trigger an alarm in CFC/PLCSIM. In OPC Scout OPC A&E view, verify that the alarm event is received with complete message text.
  4. Simulate an OS Server failover by disconnecting the master server network cable. Verify that OpenPCS7 automatically redirects queries to the standby OS Server without disconnecting the local OPC client.

Limitations and Operational Precautions

  • Virtual Machine Time Synchronization: In VM testing environments, ensure both VMs synchronize time to a common time master. Large clock skews between virtual machines will invalidate DCOM Kerberos/NTLM authentication.
  • Windows XP Legacy Warnings: Older OpenPCS7 releases running on Windows XP SP3 lack modern TLS security and 64-bit memory management. Modern industrial environments mandate Windows 10 / Server 2016 platforms.
  • OPC UA Migration: For new installations, prioritize OpenPCS7 OPC UA over classic COM/DCOM OPC DA to eliminate DCOM configuration headaches.

Engineer FAQ

Why use OpenPCS7 instead of connecting directly to the WinCC OPC Server?

OpenPCS7 provides a protective firewall and buffer for the production OS servers, handles redundant server failover automatically, and provides unified access to multiple OS servers across a distributed plant.

What license is required for OpenPCS7?

OpenPCS7 requires a dedicated SIMATIC PCS 7 OpenPCS7 runtime license installed on the OpenPCS7 station via Automation License Manager.

Does OpenPCS7 support historical data queries (OPC HDA)?

Yes. OpenPCS7 natively supports OPC HDA, querying historical process value archives and compressed data from the WinCC OS servers or Process Historian.

What is error 0x80040154 in OPC Scout?

Error 0x80040154 means 'Class not registered'. It indicates that the requested OPC COM server GUID is not registered in the Windows Registry. Reinstall or repair the OpenPCS7 software.

Can OpenPCS7 run on the same computer as an OS Client?

Yes. OpenPCS7 can be installed on an OS Client station, allowing the machine to operate both as an operator terminal and an OPC gateway.

Technical References

Related Articles

Related Tags

  • OpenPCS7
  • OPC DA
  • OPC AE
  • OPC Scout
  • OS Server
  • DCOM
  • SIMATIC NET
6 respuestas