Interpreting Engineering Station Unlimited AS RT PO and 2-Hour OS Test Mode Licensing (6ES7658-5AX18-0YA5)

The Siemens SIMATIC PCS 7 V8.1 Engineering license (MLFB 6ES7658-5AX18-0YA5) is a dedicated Engineering Station (ES) license authorizing unlimited AS engineering and configuration with a 2-hour OS Runtime test mode, not a production runtime license. The 'unlimited PO for 2-hour OS test mode' clause means an engineer can compile projects of any Process Object (PO) size and activate WinCC Runtime on the ES station for testing without license errors for exactly two continuous hours. After two hours, WinCC transitions into Demo Mode. This license cannot be used for commercial plant operation; production Operator Stations strictly require separate WinCC OS Server / Single Station Runtime licenses (such as 6ES7658-2CX18-0YB0) sized to the plant's PO count.

Engineering Station License Scope: AS Engineering vs OS Runtime

When procuring software for SIMATIC PCS 7 V8.1, automation engineers frequently consult the official Siemens ST PCS 7 Catalog and encounter order number 6ES7658-5AX18-0YA5 (SIMATIC PCS 7 AS/OS Engineering Software V8.1). The catalog description notes: 'Unlimited PO, activated for 2 hours OS Test Mode'.

A dangerous procurement misconception is assuming this single license authorizes unlimited Process Objects for a permanent Operator Station. In Siemens industrial licensing governance, software entitlements are strictly categorized:

Software License PackageCommercial Order Number (MLFB)Primary Functional ScopePermitted Production Runtime UsagePCS 7 AS/OS Engineering V8.16ES7658-5AX18-0YA5Unlimited AS/OS engineering, STEP 7, CFC, SFC, WinCC RCProhibited (Test Mode only, 2-hour limit)PCS 7 OS Software Single Station6ES7658-2AX18-0YB0Standalone Operator Station runtime visualizationApproved for production (Sized by PO: 250 to 5,000)PCS 7 OS Software Server6ES7658-2CX18-0YB0Dedicated OS Server runtime visualizationApproved for production (Requires Server RT PO)CPU 410-5H System Expansion Card6ES7653-2Cx00-0XB0Physical controller hardware execution capacityApproved for production (100 to 2,600+ PO)

The engineering license is designed exclusively for the programming master station.

Understanding the 2-Hour OS Runtime Test Mode

During commissioning and factory acceptance testing (FAT), automation engineers must verify WinCC faceplates, graphic screens, scripts, and alarm routing directly on the Engineering Station without having to deploy physical OS Servers.

To support this engineering workflow without imposing additional software costs, Siemens embeds the 2-Hour OS Test Mode:

When an engineer clicks Activate Runtime in WinCC Explorer on the ES, the Automation License Manager (ALM) verifies the 6ES7658-5AX18-0YA5 engineering license.
ALM authorizes WinCC Runtime to execute with unlimited Process Objects and unlimited archive tags for exactly 120 minutes.
Once the 120-minute countdown expires, WinCC does not immediately crash; instead, it enters Demo Mode.
In Demo Mode, recurring system dialog boxes pop up every 10 minutes warning that the evaluation period has expired, and operator input actions are periodically blocked.

Commercial Licensing Architecture: Engineering vs Production Runtime

Plant owners must understand that operating a production facility on an Engineering Station license using the 2-hour test mode violates Siemens software licensing terms and creates severe operational hazards:

Disrupted Plant Operation: Once the 2-hour window expires, pop-up boxes disrupt operator visualization, potentially blocking access to emergency trip faceplates during critical plant events.
Auditing Non-Compliance: Operating production systems without legitimate runtime licenses fails pharmaceutical (GMP), safety, and corporate software compliance audits.

To transition an engineered project into commercial production, the procurement schedule must specify:

OS Server Runtime Licenses: Sized according to plant Process Object count (e.g. 6ES7658-2CX18-0YB0 with PO expansion packages).
WinCC Redundancy Option: If operating a redundant server pair.
OS Client Licenses: One 6ES7658-2CX18-0YB5 license per physical operator client station.

Verification

Verify engineering license booking and runtime test mode limits through these diagnostic steps:

ALM License Inventory Audit: Launch Automation License Manager on the ES. Verify that SIMATIC PCS 7 Engineering V8.1 displays with license type Floating and status OK.
Launch OS Test Mode: In WinCC Explorer on the ES, click Activate. Confirm that WinCC Runtime launches smoothly without displaying missing license warnings.
Monitor ALM Active Bookings: In ALM, select View -> Log. Confirm that WinCC books the engineering license for the 2-hour test window.

Limitations and Operational Precautions

When planning and purchasing SIMATIC PCS 7 software licenses, adhere to these mandatory commercial and technical guardrails:

Commercial Accuracy Notice: Siemens software licenses, runtime Process Object (RT PO) capacities, and server options are governed by Siemens End User License Agreements (EULA) and Product Specific Terms. Never attempt to substitute an Engineering Station license (6ES7658-5AX18-0YA5) for a production Operator Station license (6ES7658-2CX18-0YB0). Sizing of runtime licenses must be calculated from the actual active technological block count in the project. Always validate final license quantities and order numbers (MLFBs) against current Siemens catalogs and authorized distributor quotations.
Redundant OS Server Licensing: A redundant OS Server pair requires two separate OS Server runtime licenses and two matching PO packages—one for each physical server.
AS RT PO Accounting: AS RT PO software licenses authorize controller logic compilation on the ES, while CPU 410 System Expansion Cards (SEC) govern physical hardware execution limits in the controller.

Engineer FAQ

Can I restart WinCC Runtime every 2 hours to keep using the ES as an operator station?

While technically possible, doing so violates Siemens license agreements and leaves the plant completely unmonitored during the restart period. It is strictly prohibited in commercial production environments.

Does the ES license allow me to download to an unlimited number of AS controllers?

The ES license allows programming multiple AS controllers, but each individual controller (or CPU 410 SEC card) must possess sufficient AS RT PO entitlements for the logic downloaded.

What is the difference between Single Station license and Server license?

A Single Station license is for a standalone PC that acts as both server and local operator screen. A Server license is for a dedicated central server that distributes visualization data to multiple OS Clients across the Terminal Bus.