Configuring OS Simulation in SIMATIC PCS 7 Engineering Stations

To execute an OS Simulation in SIMATIC PCS 7 without errors, verify that symbolic connection names between OS-to-AS and ES-to-AS in NetPro are identical, and ensure that the Engineering Station connection ID is configured higher than 0x0C00 to prevent AS diagnostic alarms. Be aware that OS Simulation establishes a live, active communication link to physical automation controllers (or S7-PLCSIM); any operator commands or setpoint adjustments executed in simulation directly manipulate running plant processes. During simulation, cross-server communications—such as historical trends or alarms from neighboring OS servers—are not routed to the local simulation session.

Functional Principles of OS Simulation in PCS 7

The OS Simulation feature in SIMATIC PCS 7 allows control engineers to test WinCC runtime graphics, APL faceplates, script logic, and alarm annunciation directly on the Engineering Station (ES) without downloading the compiled project to a physical Operator Station. This dramatically accelerates software validation during FAT and commissioning.

However, OS Simulation is not an isolated sandbox: it launches a fully functional WinCC Runtime environment on the ES. It utilizes the local communication stack to exchange process values with either physical S7-400/CPU 410 controllers or virtual controllers running in S7-PLCSIM. Understanding its network architecture and operational boundaries is critical to avoiding unintended plant disturbances.

Connection Alignment and NetPro Symbolic Naming Rules

For OS Simulation to establish communication with the target automation system, the underlying S7 connection parameters must match:

Identical Symbolic Connection Names: In NetPro, the configured S7 Named Connection from the Operator Station to the AS (e.g., OS_to_AS1) must have an exact symbolic equivalent on the Engineering Station (ES_to_AS1). If symbolic connection names differ, WinCC Runtime cannot route tag requests to the local SIMATIC NET communication channel.
Reference OS Requirements: When testing a Reference OS (a thin OS client or redundant partner configured to mirror a Base OS), all symbolic connections defined in the Reference OS must match the Base OS exactly. Otherwise, communication via Named Connections fails immediately.
Connection ID Threshold (> 0x0C00): To prevent the controller from generating connection monitoring error messages in the AS diagnostic buffer when the OS simulation starts or terminates on the ES, the connection resource ID assigned to the engineering station should be configured higher than 0x0C00 (decimal 3072).

Operational Impact: Live AS vs S7-PLCSIM Simulation

Engineers must recognize whether the OS Simulation is connected to live physical hardware or virtual simulation:

Live AS Controllers: If the Engineering Station has physical Industrial Ethernet access to the plant automation systems, the OS Simulation establishes a live Named Connection to the running CPU! Any button clicked on a faceplate (e.g., starting a pump, opening a control valve, changing a PID setpoint) executes directly in the physical controller and impacts the live plant process!
PLCSIM Virtual Controllers: For isolated software testing, the AS program must be downloaded to S7-PLCSIM, and the PG/PC Interface on the ES set to PLCSIM.TCPIP.1. This decouples the simulation completely from physical machinery.

Technical Requirements and Connection Parameters

The table below outlines key technical requirements and architectural differences when running OS Simulation.

Engineering FeatureLive Physical OS RuntimeOS Simulation on Engineering StationExecution PlatformPhysical OS Server / Single StationLocal Engineering Station (ES)Target ControllerPhysical S7-400 / CPU 410-5HPhysical CPU or S7-PLCSIM virtual controllerProcess ImpactControls live industrial processDirect live process impact if connected to physical ASCross-Server RoutingFull multiserver client-server package accessNo cross-server communication; isolated to simulated OSArchive Data SharingCentral Process Historian / Tag Logging archivesLocal temporary archive; does not replicate to serversConnection ID RuleStandard OS connection allocationConnection ID should be > 0x0C00 to prevent AS alarms

Step-by-Step Procedure to Launch OS Simulation

Follow this procedure to safely configure and execute OS Simulation in SIMATIC Manager:

Align Connections in NetPro:
- Open NetPro on the ES. Verify that S7 Named Connections from ES to AS and OS to AS share identical symbolic names.
- Save, compile, and download the connection configuration to the local PC Station.
Compile the Operator Station:
- In SIMATIC Manager Component View, right-click the target OS object and select Compile.
- Select Entire OS with memory tags. Ensure compilation finishes with zero errors.
Launch OS Simulation:
- Highlight the compiled OS object in SIMATIC Manager.
- Select Options -> OS Simulation -> Start OS Simulation (or click the Simulation toolbar icon).
- WinCC Runtime initializes on the ES, loading project graphics and process variables.
Terminate Simulation Gracefully:
- In WinCC Runtime, click the standard Exit Runtime button or press Alt + F4.
- Allow WinCC database daemons to detach cleanly before compiling or downloading.

Verification

Verify OS Simulation functionality through the following checks:
1. Verify tag connectivity: open an APL block icon (e.g., MotL or PIDConL) in simulation; confirm that process values display without gray invalid flags.
2. Test alarm processing: force an alarm in S7-PLCSIM or test logic; verify that the alarm appears in the WinCC alarm banner.
3. Check AS diagnostic buffer: verify that no connection abort or resource overrun messages are logged when simulation starts or exits.
4. Verify faceplate navigation: click block icons to ensure technological faceplates open smoothly.

Limitations and Operational Precautions

Never launch OS Simulation on an Engineering Station connected to a running production network unless strictly authorized for live commissioning. Because OS Simulation issues real commands to configured controllers, accidental manipulation can cause plant shutdowns or safety hazards. Always disconnect the ES from physical plant networks or route through S7-PLCSIM when performing logic verification.

Engineer FAQ

Can OS Simulation display trends from other OS Servers in a multiserver project?

No. During OS Simulation on the ES, cross-server communication is inactive. Distributed server data, such as WinCC OnlineTrendControl curves originating from another OS server, will not display.

Why do tags show exclamation marks or gray backgrounds in OS Simulation?

This indicates connection failure between the ES and the AS. Check that the PG/PC Interface is assigned correctly (e.g. PC Internal or PLCSIM) and that symbolic connection names match in NetPro.