Interfacing PCS 7 V8.2 with Third-Party Automation Systems Using OpenPCS 7 and OPC UA

To interface a SIMATIC PCS 7 V8.2 system (featuring redundant OS servers and non-redundant AS controllers) with a third-party automation package (such as a proprietary steam plant) via OPC UA, deploy an OpenPCS 7 Station. OpenPCS 7 acts as a standardized, redundant OPC UA server that communicates with the redundant OS servers over the Terminal Bus, aggregates process tags, alarms, and historical archives, and exposes them securely to external third-party OPC UA clients without burdening the controller Plant Bus. Deploying OpenPCS 7 requires installing the OpenPCS 7 software package and procuring the corresponding OpenPCS 7 runtime license validated through an authorized Siemens distributor quotation.

Executive Summary

Modern industrial complexes frequently integrate packaged vendor skids—such as boilers, chillers, water treatment skids, and steam turbines—controlled by third-party proprietary automation platforms. When operating a central SIMATIC PCS 7 V8.2 distributed control system, plant architects must establish robust, bi-directional parameter exchange (setpoints, process values, alarms, and permissives) with these package units. The internationally recognized standard for vendor-neutral interoperability is OPC Unified Architecture (OPC UA). In SIMATIC PCS 7, native OPC UA server capabilities are provided by OpenPCS 7. This article outlines the system architecture of OpenPCS 7, explains the communication topology, and details engineering and licensing requirements.

Architecture and Fundamental Mechanics

OpenPCS 7 Architecture, Redundant SCADA Aggregation, and OPC UA Security Profiles:

Architectural Placement of OpenPCS 7 in PCS 7 V8.2:
In PCS 7, controllers (S7-400 / CPU 410) are shielded from external non-deterministic IT traffic.
Direct OPC communication into the AS controller is strictly discouraged. Instead, Siemens provides OpenPCS 7 as an enterprise integration layer.
The OpenPCS 7 station resides on the Terminal Bus (never on the Plant Bus). It can run on a dedicated industrial PC or be co-located on an OS Single Station or OS Client.
It establishes internal connections to both OS Server 1 and OS Server 2 (redundant pair), automatically managing failover. If OS Server 1 stops, OpenPCS 7 switches seamlessly to OS Server 2 without dropping the third-party OPC UA session.
Supported OPC Interfaces in OpenPCS 7 V8.2:
OPC UA DA (Data Access): Real-time reading and writing of process tags, setpoints, and status words.
OPC UA HDA (Historical Data Access): Querying historical trends and process value archives stored in Microsoft SQL Server.
OPC UA A&C (Alarms & Conditions): Subscribing to sequence of events (SOE) process alarms, warnings, and acknowledgments.
Commercial and Licensing Guardrails:
Operating OpenPCS 7 requires a dedicated software license package (SIMATIC PCS 7 OpenPCS 7 V8.2).
OpenPCS 7 licensing is separate from AS and OS Process Object licensing.
If third-party clients query historical archives, appropriate OS Archive or Process Historian licensing must be verified.
All license quantities, order numbers, and optional packages must be validated against official Siemens catalogs and an authorized distributor quotation.

Step-by-Step Implementation Procedure

Plan the PC Station Architecture:
* Determine whether OpenPCS 7 will run on a dedicated PC Station (recommended for high tag throughput) or on an existing OS Client.
* Ensure the station connects to the Terminal Bus network and can ping the redundant OS Servers.
Configure the OpenPCS 7 Station in SIMATIC Manager:
* In Component View, insert a new SIMATIC PC Station (e.g. OPENPCS7_STATION).
* Open HW Config for the station.
* In Slot 1, insert OpenPCS 7 from the hardware catalog (SIMATIC PC Station > HMI).
* In Slot 2, insert IE General (network adapter for Terminal Bus).
* Save and compile HW Config.
Assign Server Packages to the OpenPCS 7 Station:
* In SIMATIC Manager, expand OPENPCS7_STATION to view the OpenPCS 7 object.
* Right-click the object and select Object Properties.
* In the Server Package tab, select the redundant OS Server package (e.g. OS_SERVER_PRJ).
* Save and compile the OpenPCS 7 configuration.
Configure OPC UA Security and Endpoints:
* On the physical OpenPCS 7 machine, install the SIMATIC OpenPCS 7 V8.2 software package and license key via ALM.
* Open the OpcUaServerWinCC.xml configuration file in the OpenPCS 7 directory.
* Configure the TCP port (default is opc.tcp://<Hostname>:4862 or 4840).
* Configure security policies: choose Basic256Sha256 with Sign & Encrypt, or configure trusted client certificates.
Connect Third-Party OPC UA Client:
* On the third-party steam package controller, launch its OPC UA Client.
* Connect to the endpoint: opc.tcp://<OpenPCS7_IP>:4862.
* Trust certificates between OpenPCS 7 and the third-party client.
* Browse the tag hierarchy; map required setpoints and process values.

Verification

In the third-party OPC UA client, browse the tag tree; verify that PCS 7 plant hierarchy folders and tag names appear cleanly.
Write a test setpoint from the third-party client; verify in WinCC Runtime and CFC that the value updates in under 200 ms.
Deactivate OS Server 1; verify that OpenPCS 7 maintains the OPC UA session through OS Server 2 with zero communication loss.

Limitations and Operational Precautions

Never connect third-party OPC clients directly to the Plant Bus or AS controllers; all external integration must pass through OpenPCS 7 or a dedicated communication gateway to preserve deterministic control cycle times. Ensure proper firewall port rules for TCP 4862 / 4840.

Engineer FAQ

What is OpenPCS 7 used for?

OpenPCS 7 provides a standardized, redundant OPC UA / OPC DA server interface to exchange process data, alarms, and archives with third-party systems.