Resolving OS Engineering License Errors During WinCC Runtime Testing on Engineering Stations

When opening WinCC Explorer or activating WinCC Runtime on a SIMATIC PCS 7 Engineering Station (ES) and Automation License Manager (ALM) generates an 'OS Engineering License Error' or missing license warning, the failure stems from a fundamental licensing distinction between engineering and runtime operations. An Engineering Station requires an OS Engineering (RC) license (e.g., SIMATIC PCS 7 OS Engineering) to open WinCC Explorer and configure pictures. If an engineer attempts to activate full WinCC Runtime (Activate) on the ES to test graphics, WinCC demands a concurrent OS Runtime (RT) license and Process Object (PO) entitlement. To test operator graphics on an ES without purchasing a dedicated production OS Runtime license, engineers should utilize the built-in 'OS Simulation' feature (Test -> OS Simulation in SIMATIC Manager) or configure standard WinCC Autostart on dedicated production OS servers.

Differentiating Engineering (RC) vs Runtime (RT) Licensing in PCS 7

Siemens SIMATIC PCS 7 software licensing separates configuration environments from process visualization execution environments:

Engineering Licenses (RC - Runtime & Configuration): The PCS 7 Engineering license package installed on the ES authorizes engineers to use SIMATIC Manager, CFC, SFC, and open WinCC Explorer in design mode to edit graphics, tags, and scripts.
Runtime Licenses (RT - Runtime Only): Production Operator Stations (OS Servers and OS Single Stations) utilize PCS 7 OS Software Server or OS Software Single Station licenses, scaled strictly by the number of active Process Objects (PO). These licenses allow running WinCC Runtime continuously to control plant operations but do not permit editing CFC charts.

When an engineering team builds an ES, the station typically possesses an RC Engineering license, but does not possess a multi-thousand Process Object OS Runtime license intended for dedicated plant servers.

Why Activating Runtime on an Engineering Station Triggers License Faults

When an engineer opens the OS project on the ES and clicks the 'Activate' button (traffic light icon) in WinCC Explorer to test faceplates, WinCC switches into full production runtime mode:

Operational ActionExecuting ProcessRequired ALM License KeyTypical Error on ESOpening WinCC ExplorerCCProjectMgr.exePCS 7 OS Engineering (RC)Missing license error if only RT license installedActivating Full Runtimepdlrt.exe, CCDataMgr.exePCS 7 OS Runtime (RT) + PO countLicense Error: RT license missing or PO count exceededLaunching OS SimulationSimulate.exeAuthorized via Engineering (RC) licenseNo Error: Runs in temporary testing containerAutostart on Dedicated OSAutoStartRT.exePure OS Runtime (RT) licenseHealthy: Launches runtime without opening WinCC Explorer

Because full runtime activation on the ES attempts to validate hundreds of compiled process objects against an OS RT license that does not exist on the engineering PC, ALM triggers an aggressive license violation popup every 10 minutes.

Testing Graphics via OS Simulation vs Production Autostart

To test operator pictures and faceplate interactions without triggering licensing errors, apply the correct technical workflow:

Testing on the Engineering Station: Deploy 'OS Simulation'
1. In SIMATIC Manager, navigate to the Component View.
2. Right-click the OS project object and select Test -> Start OS Simulation (or select the OS and click the Simulation icon).
3. SIMATIC Manager launches WinCC Runtime in an isolated simulation mode linked to the Engineering license.
4. When paired with S7-PLCSIM, engineers can fully test motor faceplates, interlocks, alarm banners, and trend curves without requiring an OS RT license or stopping production.

Deploying on Dedicated OS Servers: Configure WinCC Autostart
On production OS Servers and Single Stations that possess only RT licenses:
1. Open Windows Start Menu -> Siemens Automation -> Autostart.
2. Select the path to the downloaded WinCC project file (<ProjectName>.mcp).
3. Enable Activate project when computer starts.
4. Upon station reboot, WinCC enters runtime directly without opening WinCC Explorer, remaining 100% compliant with OS Runtime (RT) licensing.

Verification

Verify license allocation and simulation testing using these diagnostic checks:

ALM License Inventory Audit: Open Automation License Manager on the ES. Verify that SIMATIC PCS 7 Engineering or WinCC Engineering displays status OK with valid expiration dates.
OS Simulation Launch Test: From SIMATIC Manager, initiate Start OS Simulation. Confirm that WinCC Runtime activates cleanly without displaying an Automation License Manager missing-key warning banner.
Process Object Check: In WinCC Explorer, select the project name, right-click, and select Properties. Under the Statistics tab, verify that the configured Process Object count is within legal project boundaries.

Limitations and Operational Precautions

When configuring licensing across engineering and runtime systems, observe these rules:

Trial License Expiration: If running under a 14-day trial license during commissioning, ensure permanent commercial license keys are transferred before the trial expires; an expired trial causes WinCC to drop client connections.
Floating License Network Sharing: If the ES uses a central license server via network ALM, verify that network latency between the ES and license server is under 20ms and that TCP Port 4410 (ALM communication) is open in the firewall.
Commercial Procurement and Licensing Disclaimer: Distinguish AS RT PO licenses (which run on the CPU) from OS RT PO licenses (which run on WinCC). Verify all order numbers (MLFBs) and Process Object package tiers with an authorized Siemens distributor.

Engineer FAQ

Can I purchase an OS Runtime license for my Engineering Station?

Yes. If an Engineering Station is intended to serve as a combined ES/OS Single Station in a small plant, you can purchase a combined ES/OS Single Station package that includes both RC and RT entitlements.

Why does WinCC ask for an OS Engineering license on an OS Client?

An OS Client only possesses an OS Client Runtime license. If a technician attempts to open WinCC Explorer directly on the client rather than letting runtime start automatically, WinCC will demand an Engineering license.

Does OS Simulation allow testing communication with a physical AS?

Yes. OS Simulation can connect either to virtual S7-PLCSIM or to a physical S7-400 controller via the configured Named Connection in Set PG/PC Interface.