Resolving WinCC Flexible 2005 OP77A Simulator Not Available Error

Problem: OP77A Simulator Not Available in WinCC Flexible 2005

When configuring an OP77A or any other small Siemens HMI panel in WinCC Flexible 2005 Advanced and attempting to launch the runtime simulator from the project tree, the configuration tool returns the dialog "Error: The runtime simulator is not available for this device." The Start RT command either becomes disabled, or the simulator process fails to start with the error above. This blocks offline commissioning workflows that depend on screen-to-PLC logic verification before a physical panel is connected to the line.

The error is generated by WinCC Flexible 2005 SP1, SP2, SP3, and earlier 2005 builds when the active project target is one of the micro-class 170/73/77 panels. The configuration environment does not ship a runtime image for these devices, and the menu command cannot redirect to a compatible emulator because the runtime DLL set was never compiled into the 2005 release line. This is a hard product feature boundary, not a configuration error.

Root Cause: Simulator Feature Added in WinCC Flexible 2007

Siemens added PC-based runtime simulation for the small operator panels - specifically OP 73, OP 73micro, OP 77A, TP 177A, and TP 177micro - in WinCC Flexible 2007. The 2005 release line predates this feature and ships with simulator binaries only for the 170/270/277 series panels and the MP/Mobile panel families. When the configuration tool checks the device profile of the active project and finds an unsupported target, it suppresses the Start RT option and surfaces the "runtime simulator is not available for this device" message if the command is invoked from another path.

This behavior is documented in the official Siemens Knowledge Base under article ID 26169252. The article lists the device families whose PC simulation was introduced in WinCC Flexible 2007. The same feature remains present in WinCC Flexible 2008, 2008 SP1, SP2, SP3, and the final 2008 SP5 release that closed the WinCC Flexible product line. From WinCC Flexible 2008 SP2 onward, the PC simulation runtime for the 170-class panels is functionally equivalent to the on-device runtime for I/O, screen navigation, alarm handling, recipe handling, and tag logging tasks. Trends and VB scripts are also fully exercisable in the simulator.

The underlying implementation change between 2005 and 2007 was a re-architecting of the WinCC Flexible runtime to share a common Win32 emulation layer across all panel classes. The 2005 runtime was split into separate DLL groups per panel class, and the micro-class panels did not have a PC-emulation DLL in the distribution. The 2007 release merged the runtime into a single module that could target any device profile, which is what enabled PC simulation for the small panels. This architectural change is also why some legacy field reports describe the OP77A simulator as "working in 2007 but crashing in 2005 SP3 with a missing DLL" - the underlying binary was not present in 2005 at all.

Affected Devices and Software Versions

The simulator-unavailable behavior is reproducible on every device profile listed below when the configuration tool is WinCC Flexible 2005 (any service pack) or earlier. The same device profiles are fully simulable on WinCC Flexible 2007 and 2008.

Devices that do have PC simulator support in WinCC Flexible 2005: OP 170B, OP 170A, TP 170A, TP 170B, TP 170micro, TP 170color, TP 270, OP 270, MP 270, MP 270B, MP 370, MP 377, Mobile Panel 170, Mobile Panel 177, and the PC Runtime (WinCC Flexible RT 2005). If your project targets one of those devices, the Start RT button in WinCC Flexible 2005 will work normally and the "not available" error will not appear.

The OP77A, OP73, and OP73micro panels are typically connected to S7-200 PLCs over PPI or MPI. The TP 177A and TP 177micro panels add PROFIBUS support and are also frequently paired with S7-300/400 controllers. The PPI/MPI cable and addressing conventions are unchanged between 2005 and 2008; the only difference relevant to the simulator is whether the runtime binary is bundled with the configuration tool.

Diagnostic Checklist Before Concluding the Feature Gap

Before treating the error as the known 2005 feature gap, run through the following checks to rule out other causes that can produce a similar message in different configuration tools:

1. Confirm the active device: In the project tree, right-click the HMI station and select Device Properties. The Device tab lists the exact order number. Cross-check the result against the matrix above.
2. Confirm the WinCC Flexible version: Open Help -> About. The version string V1.x corresponds to 2005; V1.3 with SP suffix is 2005 SP3; V1.4 begins WinCC Flexible 2007. The exact build string and SP level should be noted for the support ticket if the issue persists after upgrade.
3. Confirm the project is compiled: If the project is in a "modified" state with no recent compile, some Start RT paths will refuse. Run Project -> Compiler -> Compile and Check Consistency first. Resolve every error and warning before re-attempting simulation.
4. Confirm the simulation flag is set: In the project tree, click the HMI station, then in the work area open Runtime Settings -> Runtime tab and verify the simulation/start option is enabled. Some 2005 templates ship with this unchecked.
5. Check the WinCC Flexible RT service: The PC simulator requires the WinCC flexible RT service to be installed and started. Verify via services.msc. If the service is missing, reinstall the WinCC Flexible RT component from the original installation media.
6. Check firewall exceptions: The simulator opens local TCP ports in the 3000-3010 range and the OPC tunnel uses fixed ports. Windows Firewall can block them silently and produce a secondary "RT cannot be reached" error that can be misread as the "not available" message. Add the WinCC flexible RT executable to the firewall exception list.
7. Check OPC and DCOM permissions: If the simulator uses OPC tags to a remote PLC, verify DCOM is configured on the developer PC. This is a common cause of secondary errors on Windows 10/11.

If all seven checks pass and the device is one of the five listed in the matrix, the behavior is the known 2005 feature gap and you must move to one of the solutions below.

Solution 1: Upgrade to WinCC Flexible 2008 SP5

This is the only method that retains the exact WinCC Flexible 2005 project file format and does not require a TIA Portal conversion. WinCC Flexible 2007 and 2008 read .hmi and .log files created in 2005 with no conversion dialog. All screens, tags, alarms, recipes, scripts, and connections are preserved.

1. Verify project compatibility: Open the 2005 project, run Project -> Compiler -> Check Consistency. Fix any warnings. A "Project OK" state is required before opening the project in 2007 or 2008.
2. Install WinCC Flexible 2008 SP5 (the highest 2008 release). Select Complete install to include the PC Runtime and the simulation component. The install package is the "WinCC_flexible_2008_SP5.exe" available from the Siemens Industry Online Support portal.
3. Open the 2005 project: Launch WinCC Flexible 2008, choose Open an existing project, and select the .hmi file. The tool will perform an internal upgrade of the project metadata. Save the upgraded copy under a new name to preserve the original 2005 source as a backup.
4. Open the device properties for the OP77A and verify the Simulation option is now enabled in the menu bar's Runtime group.
5. Click Start RT (the play-button icon) to launch the simulator. A windowed representation of the OP77A faceplate opens on the developer PC, with all keys and the touchscreen active.
6. Connect to the S7-200 or S7-300/400 PLC using the configured protocol (PPI, MPI, PROFIBUS, or Ethernet). For offline tag testing without a real PLC, use the Tag Simulator tool launched from the same Runtime menu group.

The upgrade from 2005 to 2008 does not change the runtime binary that downloads to the physical OP77A panel. The compiled .img file generated by 2008 is compatible with the panel firmware. The PC simulation runs entirely on the developer PC and does not interact with the physical panel unless the user explicitly starts a transfer.

Solution 2: Migrate to TIA Portal V20 and Use RT Professional

For greenfield projects or projects where the customer is willing to invest in a one-time TIA Portal migration, the modern path is to import the WinCC Flexible 2005 project into TIA Portal and use the RT Professional simulator. The official TIA Portal V20 documentation covers the simulation workflow in detail.

RT Professional is the successor runtime that replaced WinCC Flexible RT for PC-based panels starting with TIA Portal V13. It supports Comfort Panels, WinCC Runtime Advanced, and the Unified Comfort Panels. The small OP 73, OP 73micro, OP 77A, TP 177A, and TP 177micro panels are not directly supported as TIA Portal V20 HMI targets, so a migration to TIA Portal typically also means migrating to a newer physical panel (a Comfort Panel or Unified Comfort Panel).

For projects that must remain on the OP77A hardware but want to use TIA Portal simulation for the logic side, a common field practice is to keep the HMI project in WinCC Flexible 2008 (per Solution 1) and migrate the PLC project to TIA Portal. The PLC simulation can then be performed in PLCSIM (S7-PLCSIM or PLCSIM Advanced) while the HMI is validated against the simulated PLC through WinCC Flexible 2008's built-in connection to PLCSIM.

The official TIA Portal V20 documentation page for simulating a project in RT Professional is published at the Siemens Documentation Hub: Simulating a project (RT Professional) - TIA Portal V20. The page documents prerequisites, the local PC runtime installation, and the "Start Simulation" button behavior in the TIA Portal project tree.

Solution 3: Validate on the Physical Panel

If upgrading or migrating is not feasible (for example, a locked production line that cannot accept a new HMI image mid-shift, or no SUS contract for a license key), the original 2005 project can still be commissioned by downloading it to the physical OP77A and exercising it there. The PC simulator is a development convenience, not a deployment requirement.

1. Connect the OP77A to the development PC using the PC/PPI cable (RS-232 PPI/MPI) or a USB/PPI adapter. The exact order number varies by Siemens catalog revision - consult the OP77A device manual for the current recommendation. Set the OP77A transfer mode via the panel's own settings menu (Control Panel -> Transfer).
2. In WinCC Flexible 2005, configure the transfer channel under Project -> Transfer -> Transfer Settings. Select Serial or USB as appropriate and match the baud rate to the OP77A's PPI/MPI port. The PPI standard baud rates are 9.6 kbps, 19.2 kbps, 187.5 kbps, and 1.5 Mbps; consult the OP77A device manual for the exact list supported by the panel firmware version in use.
3. Click Transfer -> To Device -> Available Devices in WinCC Flexible 2005. The tool will scan and find the OP77A by its MPI/PPI address.
4. Download the compiled project. The OP77A reboots into the new image. Use the physical keys and any connected PLC tags to validate behavior.

This path sacrifices the offline testing convenience of the simulator but produces a fully validated runtime on the target hardware. For 2005 projects targeting the OP77A in active production, this remains a common practice in sites that have not yet consolidated onto TIA Portal.

Verifying the Simulator After Upgrade

Once WinCC Flexible 2008 SP5 is installed and the 2005 project has been opened and saved in 2008, perform this verification sequence to confirm the OP77A simulator is functional:

1. Open the project in WinCC Flexible 2008 SP5. In the title bar, confirm the version string contains "2008 SP5."
2. In the project tree, the device name should read "OP 77A" as configured. Right-click the device and open Device Properties. The General tab should display the order number and a "Simulation supported: Yes" indicator.
3. Build the project: Project -> Compiler -> Rebuild All. Address any errors. The Compile output window should report "0 errors, 0 warnings" before proceeding.
4. Click Start RT in the runtime toolbar. A window titled WinCC flexible Runtime - [ProjectName] should open within 5 to 10 seconds on a typical developer PC. The window dimensions match the OP77A's 4.5-inch faceplate geometry, scaled to a larger window on the PC screen.
5. Click any function key or touch area. The configured screen change or tag write should execute. Verify the tag value updates in the Tag Simulator tool or by attaching a watched tag to the online PLC.
6. Open the WinCC Flexible 2008 help: Help -> Contents -> Runtime and Simulation -> Simulating a Project. This help topic exists in 2008 but does not exist in 2005, which is a quick version-difference check.

Troubleshooting Matrix

Commissioning Best Practices for OP77A Projects

When commissioning or migrating OP77A projects, the following field-proven practices reduce the risk of simulator-related confusion:

• Version stamp every project file. Open Project Properties -> Comment and record the WinCC Flexible version used to last save the file. This is the single fastest way to diagnose the "simulator not available" error when the file moves between engineers.
• Run the simulator before any hardware download. Even if the physical panel is available, the PC simulator exposes logic errors faster than a hardware loop. The 2008 SP5 simulator is the lowest-friction way to validate a 2005-origin project.
• Validate the connection to the S7-200 in the simulator first. PPI/MPI addressing errors (duplicate station addresses, mismatched baud rates) are the most common field failures. The simulator exposes these before any hardware is touched.
• Keep the 2005 project as the source of truth. WinCC Flexible 2008 can save a project that 2005 cannot re-open. Always back up the 2005 .hmi file before opening it in 2008.
• Document the cable type and baud rate in the project comment. PPI and MPI cables look similar; an unlabeled cable between an OP77A and an S7-200 is the root cause of a significant fraction of field commissioning delays.
• Use the Tag Simulator for offline logic testing. The Tag Simulator tool in WinCC Flexible 2008 SP5 lets you inject tag values into the running simulation without a connected PLC. This is the fastest way to validate alarm thresholds, screen navigation, and recipe data flows.

Migrating from PPI to Ethernet Where Possible

Long-term, sites running OP77A panels are advised to plan a migration path off the PPI/MPI bus. The OP77A does not have an Ethernet port; a typical migration is to a TP700 Comfort or KTP700 Comfort panel, both of which are fully supported in TIA Portal V20 with RT Professional simulation. The migration preserves the screen layouts and tag references if the project is converted through the TIA Portal "Migrate WinCC Flexible project" wizard. Plan for:

• Order code change: The Comfort Panel uses a 24 V DC supply and a separate order number series. Plan the panel cutout change with the mechanical design team.
• Cable change: PROFINET replaces PPI/MPI. Existing copper can sometimes be reused with media converters, but most sites plan a structured PROFINET cable pull.
• Project conversion: Run the TIA Portal conversion wizard from the WinCC Flexible 2008 SP5 source. Address the conversion report's warnings - typically tag name length, library references, and unsupported VB script functions.
• Simulator validation: Once the project is in TIA Portal V20, validate using the RT Professional simulator before any hardware is provisioned. Refer to the TIA Portal V20 RT Professional simulation documentation for the workflow.

FAQ