Integrating Third-Party OPC Servers into SIMATIC PCS 7 WinCC via the Native OPC Client Channel

To connect third-party OPC Servers (such as Kepware, Matrikon, or third-party PLC gateways) into SIMATIC PCS 7 V8.1 WinCC OS to visualize external tags alongside plant data, deploy the native WinCC OPC Communication Channel (OPC.chn) in WinCC Tag Management. While OpenPCS 7 functions exclusively as an outbound OPC Server (exposing PCS 7 data to external MES/ERP systems), native WinCC acts as an OPC DA / OPC UA Client. To maintain full redundancy, configure identical OPC channel connections on both redundant OS Servers, pointing each server to the third-party OPC source with matching tag naming and update cycles.

Executive Summary

Modern process facilities increasingly require integrating third-party package units (skids, refrigeration systems, electrical switchgear, and analytical chromatographs) that expose data via standard OPC interfaces rather than native S7 protocols. In SIMATIC PCS 7 V8.1 installations equipped with an OpenPCS 7 station, engineers frequently confuse the roles of OpenPCS 7 and WinCC, asking whether OpenPCS 7 can ingest data from external OPC servers. In reality, OpenPCS 7 operates strictly as an outbound OPC Server. To consume data from third-party OPC servers, engineers must leverage WinCC's built-in OPC Communication Channel (OPC.chn). This guide clarifies the architectural roles and details how to configure OPC client communication within a high-availability redundant OS environment.

OpenPCS 7 Server vs WinCC Native OPC Client Channel

Siemens enforces strict functional separation between OPC client and server roles:

OpenPCS 7 (OPC Server): Acts as a high-level data gateway exposing PCS 7 plant tags, historical archives, and alarm streams to external clients (e.g. MES, LIMS, SAP, third-party SCADA). It cannot act as a client or ingest external data.
WinCC OPC Channel (OPC Client): A native communication channel driver included with standard WinCC that allows WinCC to connect as a client to any compliant OPC DA (Data Access), OPC XML, or OPC UA (Unified Architecture) server.

WinCC OPC Communication Channel Architecture (OPC.chn)

The WinCC OPC channel driver operates within WinCC Tag Management:

OPC DA (Classic): Connects to local or remote OPC DA 2.05a / 3.0 servers via Windows COM/DCOM.
OPC UA: Connects to modern OPC UA servers via secure binary TCP connections (opc.tcp://), eliminating DCOM security hurdles.
Process tags read from the third-party OPC server behave identically to native S7 tags: they can be animated on graphic pictures, logged in Tag Logging, and evaluated in alarm scripts.

Configuring OPC Client Connections in Redundant OS Server Pairs

In redundant WinCC OS Server environments:

Both OS Server Master and OS Server Standby must establish independent connections to the third-party OPC server.
If the third-party OPC server is installed on a separate PC on the Terminal Bus, both servers poll the device concurrently.
If the third-party OPC server itself is redundant, WinCC's OPC channel can be configured with redundant connection pairs to provide complete end-to-end fault tolerance.

OPC Integration Methods Comparison Matrix

The following table compares OPC integration options in SIMATIC PCS 7:

Software ComponentRole in CommunicationDirection of Data FlowProtocols SupportedLicensing PrerequisiteWinCC OPC ChannelOPC ClientInbound (Reads External Data)OPC DA, OPC XML, OPC UAIncluded with WinCC RT license.OpenPCS 7OPC ServerOutbound (Exposes PCS 7 Data)OPC DA, HDA, A&E, UADedicated OpenPCS 7 license.Connectivity PackOLE-DB / OPC ServerOutbound (Archive Extraction)OLE-DB, OPC HDA, OPC A&EConnectivity Pack license.Third-Party BridgeProtocol ConverterBidirectionalModbus / OPC / ProprietarySeparate third-party package.

Step-by-Step Procedure to Integrate Third-Party OPC Tags into WinCC

Method: Configuring OPC Channel in WinCC Tag Management

On the Engineering Station, open the OS project in WinCC Explorer.
In the navigation tree, right-click Tag Management and select Add new driver.
Select OPC.chn (OPC Communication Channel) and click Open.
Expand the OPC driver in Tag Management. Right-click OPC Groups (OPCHN Unit #1) and select System Parameter.
In the OPC channel settings, click Add connection.
Select the connection type: OPC DA or OPC UA.
For OPC DA, browse the network and select the remote PC and OPC server name (e.g. Kepware.KEPServerEX.V6).
Open the connection in Tag Management. Right-click and select New Tag (or use the OPC Tag Browser to mass-import items).
Browse the third-party server's address space; select desired process tags and assign them to WinCC tag groups.
In redundant server systems, duplicate this exact driver configuration on the redundant partner server project.
Save and download the OS project to both target servers.

Verification

To verify third-party OPC communication:

Channel Diagnosis Check: In WinCC Runtime, open WinCC Channel Diagnosis. Confirm that driver OPC.chn indicates status 'OK' with green connection checkmarks.
Live Tag Updating: Open a graphic picture displaying third-party OPC tags. Confirm that values update dynamically without yellow quality warning triangles.
Redundancy Validation: Deactivate runtime on OS Server Master. Confirm that OS Server Standby maintains independent live communication with the third-party OPC server without tag freezes.

Limitations and Operational Precautions

DCOM Hardening Restrictions: If using classic OPC DA across networked computers, Microsoft DCOM security hardening patches (KB5004442) mandate packet-level authentication; prefer OPC UA whenever third-party servers support it.
PO Consumption: Tags created under the WinCC OPC channel do not consume AS Process Objects, but they do consume standard WinCC process tag license counts if operating under standard WinCC tag-based licensing.
Poll Rate Sizing: Avoid polling thousands of OPC tags at high frequencies (< 500 ms); configure appropriate update cycles (1 to 2 seconds) to avoid saturating network bandwidth.

Engineer FAQ

Can OpenPCS 7 write setpoints into PCS 7 from an external MES system?

Yes, OpenPCS 7 supports both reading and writing tags; external OPC clients can write setpoint values to technological block inputs.

Does WinCC OPC Client require a special license?

No. The WinCC OPC Communication Channel is a standard native driver included with all PCS 7 OS RT licenses.

Can third-party OPC alarms be integrated into the WinCC Alarm Control?

Yes, by connecting to an OPC A&E (Alarms & Events) server using the WinCC Alarm Logging OPC channel option.

Technical References

Related Tags

https://industrialautomation.net/search?query=simatic-pcs7
https://industrialautomation.net/search?query=wincc
https://industrialautomation.net/search?query=opc
https://industrialautomation.net/search?query=openpcs7

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Integrating Third-Party OPC Servers into SIMATIC PCS 7 WinCC via the Native OPC Client Channel