SIMATIC PCS 7 V8.1 OS Web Server Licensing: Expanding Client Quantities Using Countable Cumulative Licenses

In SIMATIC PCS 7 V8.1 (WinCC V7.3), expanding Web Server client capacity from 10 to 25 clients is accomplished using countable cumulative licenses, not legacy monolithic licenses. In WinCC V7.3 and later, WebNavigator licenses are additive: installing multiple license keys stacks their client counts in Automation License Manager (ALM). To expand a system with an existing 10-client license (6AV6362-1AF00-0BB0), you procure additional countable packages (e.g. one 10-client pack plus two 3-client packs, or a 30-client pack). Attempting to install obsolete monolithic licenses from earlier WinCC versions (such as WinCC WebNavigator 25 for V7.0) is rejected by ALM because version-specific license identifiers are incompatible.

WinCC Web Server Licensing Architecture in PCS 7 V8.1

In SIMATIC PCS 7, the OS Web Server enables distributed process visualization across corporate networks using thin-client WebNavigator or WebUX technology. Operating an OS Web Server requires two distinct software licensing entitlements in Automation License Manager (ALM):

OS Web Server Basic License: The foundational engineering entitlement (e.g., SIMATIC PCS 7 OS Software Web Server Basic V8.1, MLFB 6ES7658-2GE08-0YB0), authorizing the Web Server background services to interface with WinCC.
Web Client Licenses (Count-Relevant): Authorizes the maximum number of concurrent client sessions connected simultaneously to the Web Server.

The Countable Cumulative Licensing Model vs Legacy Monolithic Packs

A major architectural modernization occurred between older WinCC versions (V6.x / V7.0) and modern versions (WinCC V7.3 / PCS 7 V8.1):

Legacy Model (Pre-V7.3): Web licenses were non-stackable monolithic blocks (e.g. 'WebNavigator 3 Clients', 'WebNavigator 25 Clients'). If a plant had 10 clients and wanted 25, the customer had to purchase a specific 'Powerpack Upgrade from 10 to 25 Clients'. Stacking a 10 and a 25 license resulted in ALM using only the higher tier or erroring.
Countable Cumulative Model (V7.3+): Licenses are strictly additive (countable). If an OS Web Server has a 10-client license and the administrator installs a 3-client license, ALM computes total authorized capacity as 10 + 3 = 13 concurrent clients.

Why Legacy WinCC WebNavigator Licenses Are Ignored by ALM in V7.3

When an engineer installs an older license—such as WinCC WebNavigator (25) with license key identifier SISLA9WSN30703 (from WinCC V7.0)—onto a PCS 7 V8.1 system, ALM displays the key as valid, but the WinCC Web Server continues reporting only 10 clients:

WinCC V7.3 queries license family keys starting with modern version signatures.
The legacy V7.0 key lacks the internal countable attribute (Count-relevant: Yes) required by the V7.3 runtime licensing engine.
Consequently, the Web Server ignores the foreign license file completely, continuing to enforce the active 10-client limit.

Sizing and Calculating License Combinations to Expand Web Clients

Standard Siemens ordering increments for countable WebNavigator licenses are: 1, 3, 10, 30, and 100 clients.

To expand an existing 10-client Web Server to support 25 concurrent users:

Option A (Exact match): Add one 10-client package (6AV6362-1AF00-0BB0), one 3-client package (6AV6362-1AD00-0BB0), and two 1-client packages (6AV6362-1AB00-0BB0), yielding 10 + 10 + 3 + 1 + 1 = 25 clients.
Option B (Standard Expansion): Add two 10-client packages (yielding 30 clients total), which is typically more cost-effective than purchasing multiple small fractional packages.
Option C: Procure a single 30-client countable license (6AV6362-1AJ00-0BB0), bringing total server capacity to 40 clients.

Comparative Package Matrix: WinCC WebNavigator Countable Licenses

The following table details official Siemens countable WebNavigator license packages compatible with WinCC V7.3 / PCS 7 V8.1:

License DescriptionSiemens Order Number (MLFB)Count-Relevant UnitsStacking Capability in ALMCompatible WinCC ReleaseWinCC WebNavigator 1 Client6AV6362-1AB00-0BB0+1 ClientAdditive (Cumulative)WinCC V7.3 / V7.4 / V7.5WinCC WebNavigator 3 Clients6AV6362-1AD00-0BB0+3 ClientsAdditive (Cumulative)WinCC V7.3 / V7.4 / V7.5WinCC WebNavigator 10 Clients6AV6362-1AF00-0BB0+10 ClientsAdditive (Cumulative)WinCC V7.3 / V7.4 / V7.5WinCC WebNavigator 30 Clients6AV6362-1AJ00-0BB0+30 ClientsAdditive (Cumulative)WinCC V7.3 / V7.4 / V7.5WinCC WebNavigator 100 Clients6AV6362-1AM00-0BB0+100 ClientsAdditive (Cumulative)WinCC V7.3 / V7.4 / V7.5Legacy WebNavigator 25 (Monolithic)6AV6371-1DH07-0AX0Non-CountableNOT CompatibleWinCC V7.0 only

Step-by-Step License Installation and Activation Workflow

Follow this procedure to expand Web Server client licensing:

Procure Countable License: Order the required countable package (e.g. 6AV6362-1AF00-0BB0 for 10 additional clients).
Open ALM on Web Server: Launch Automation License Manager with Administrator privileges on the OS Web Server PC.
Transfer License Key: Insert the license USB stick. Drag the new countable license key onto drive C:.
Audit License Pool: In ALM, select the local drive. Locate the product name: SIMATIC WinCC / WebNavigator. Verify that the column Total number reflects the combined sum (e.g. 20 or 25).
Restart Web Services: To force the IIS Web Server to re-read ALM without rebooting Windows, open an elevated command prompt and execute iisreset.
Verify Client Connection: Connect 15 simultaneous browser sessions from test PCs; confirm none receive license shortage warnings.

Verification

Confirm license activation through these checks:

ALM Status Verification: In ALM, check the WebNavigator license. Confirm Number of license keys reflects all installed packages.
WinCC Status Control: In WinCC WebNavigator Administrator, open the User Status view. Verify concurrent connected sessions exceed 10 without rejection.
Web Client Diagnostic Log: Check C:\Program Files (x86)\Siemens\WinCC\Webnavigator\Server\log\WebLog.txt; confirm zero license expiration warnings.
Event Viewer Audit: Confirm Windows Application Event Log shows clean license grant events from CCLicenseService.

Limitations and Operational Precautions

Observe the following licensing rules:

Concurrent Not Named: WebNavigator licenses are strictly concurrent floating connections; they do not restrict the total number of configured user accounts, only the number of users logged in at the exact same moment.
Redundant Web Servers: In redundant OS Web Server architectures, both Web Servers must possess identical WebNavigator client license counts to ensure uninterrupted capacity during failover.
Commercial Accuracy Disclaimer: Software order numbers (MLFBs), package structures, and hardware capacity prerequisites vary across PCS 7 versions and hardware platforms. System integrators must confirm exact software entitlements and licensing requirements against the official Siemens Catalog CA 01 and obtain an authorized Siemens distributor quotation prior to purchasing.