Licensing Redundant WinCC OS Servers and Multi-Client Architectures in SIMATIC PCS 7

In SIMATIC PCS 7 multi-client architectures featuring redundant OS servers and 10 OS clients, software licensing requires distinct engineering, runtime, and redundancy packages rather than simple tag counts. Each redundant server requires an OS Software Server runtime package with matching Process Object (PO) capacity, while exactly one server of the pair requires an OS Redundancy license package. Every client workstation requires an OS Client software license. Final license procurement must always be validated against official Siemens catalogs and an authorized Siemens distributor quotation.

PCS 7 OS Server and Client Licensing Structure

Configuring a high-availability SIMATIC PCS 7 operator supervisory tier requires distinguishing between base software installations, runtime capacity, and functional expansion options:

OS Runtime Server License: Authorizes the WinCC server engine to process supervisory data and communicate with automation systems. Runtime capacity is governed by Process Objects (PO), not gross tag counts.
OS Redundancy Option: Enables real-time database synchronization, archive synchronization, and automated client failover between server partners over an Ethernet redundancy link.
OS Client License: Allows a client station to open process screens from connected server packages, execute operator actions, and display system alarms without consuming local server POs.
Engineering Station (ES) Licenses: Engineering licenses are distinct from runtime licenses and are installed only on the engineering computer used to compile OS projects.

Redundant Server Licensing Rules and PO Counting

When commissioning a redundant OS server pair:

Symmetric PO Capacity: Both Server A (Master) and Server B (Standby) must possess identical PO capacities. For example, if the plant contains 2,500 OS Process Objects, both servers require base server packages and cumulative PO licenses covering at least 2,500 POs.
Single Redundancy Package: The SIMATIC PCS 7 OS Redundancy software package is purchased once per redundant pair. In modern PCS 7 releases, the redundancy license is supplied as a single package installed across the servers.
Cumulative PO Expansion: If plant capacity grows, cumulative OS Runtime PO packs (e.g., +100, +500, +1,000 POs) must be purchased in duplicate and installed equally on both server stations.
Maintenance of Automation License Manager (ALM): Both servers must have their licenses transferred to their local hard drives via ALM prior to initiating WinCC Runtime.

OS Client Licensing Requirements

The client tier operates under simplified licensing rules compared to servers:

Single Client License per Station: Each of the 10 client PCs requires exactly one SIMATIC PCS 7 OS Software Client runtime license.
Multi-Server Multi-Client Capability: A licensed OS Client can connect simultaneously to multiple redundant server pairs (e.g., Area 1 Server Pair, Area 2 Server Pair, Process Historian) without requiring additional client licenses or PO allocations.
Web Clients vs Standard Clients: Standard PCS 7 OS Clients use thick-client Windows installations. If WebNavigator thin clients are utilized instead, concurrent user access licenses (e.g., 5, 10, 25 clients) are installed on the Web server rather than individual client licenses on workstations.

Procurement Schedule and License Mapping Table

The following table details the typical license structure for a PCS 7 redundant server pair with 10 clients (example 2,000 PO system in PCS 7 V8.2 / V9.0):

Workstation RoleQuantityRequired Siemens Software PackageLicense TypePurposeOS Server 1 (Master)1SIMATIC PCS 7 OS Software Server (Base PO) + PO ExpandRuntime License (Local ALM)Core supervisory server runtime executionOS Server 2 (Standby)1SIMATIC PCS 7 OS Software Server (Base PO) + PO ExpandRuntime License (Local ALM)Symmetric standby server runtime executionOS Server Pair1SIMATIC PCS 7 OS Redundancy PackageOption License (Per Pair)Inter-server database sync and client switchoverOS Clients10SIMATIC PCS 7 OS Software ClientClient Runtime LicenseMulti-screen operator console runtime authorizationEngineering Station1SIMATIC PCS 7 Engineering Software (ES)Engineering LicenseMulti-project configuration and OS compilation

Disclaimer: Siemens licensing structures, part numbers (MLFBs), and packaging models vary across PCS 7 versions. Engineers must validate exact MLFBs, PO increments, and hardware prerequisites against the official Siemens Catalog CA 01 and obtain an authorized Siemens distributor quotation prior to purchasing.

Verification

Verify licensing health and PO consumption prior to plant handover:
1. In SIMATIC Manager, right-click the OS project and select Options > Process Objects > Calculate Process Objects to verify total consumed OS POs.
2. Open Automation License Manager (ALM) on both OS servers and verify that installed OS RT PO quantities meet or exceed the calculated count.
3. In ALM on both servers, confirm the presence and validity of the PCS 7 OS Software Server and OS Redundancy license keys.
4. Open ALM on all 10 OS clients and confirm the PCS 7 OS Software Client key shows state 'Valid' without expiry dates.

Limitations and Operational Precautions

Observe these essential commercial and operational rules:
- An asymmetric PO license count between redundant servers causes the server with fewer PO licenses to enter demo mode or trigger license shortage warnings, impeding archive synchronization.
- Never infer licensing quantities solely from CPU count, I/O count, or raw tag counts; PCS 7 licenses by Process Objects (APL blocks with message/control capabilities).
- Always ensure all server and client licenses are permanently transferred to physical or virtual system storage using ALM rather than operating on temporary trial keys.

Engineer FAQ

Does each redundant OS server need its own separate redundancy license?

No. The PCS 7 OS Redundancy license package covers the redundant pair, but both servers must run identical OS Runtime PO license capacities.

Do OS clients consume Process Objects (POs)?

No. Process Objects are counted and licensed exclusively on the OS Servers. OS Clients only require the single OS Client software license.

What happens if an OS server exceeds its licensed PO count in runtime?

WinCC displays periodic license warning dialogs and generates system alarm messages. While runtime typically continues without shutting down the plant, non-compliance must be corrected immediately.