Problem Statement: Disabled Start-Runtime (RT) Button in TIA Portal
Engineers configuring SIMATIC Basic Panels (KTP400, KTP700, KTP900, KTP1200, and the older OP 73 / TP 177 series) inside TIA Portal frequently report that the toolbar icon labeled "Start Runtime" (abbreviated RT) remains permanently grayed-out, even when the project is fully compiled, the HMI device is online, and no compile errors are reported. The same symptom appears next to the simulation icon and is sometimes mistaken for a software defect, missing add-on, or a corrupted installation.
The RT button is not broken. It is a license- and edition-gated feature that is intentionally disabled when the active engineering environment cannot host the runtime image. Understanding the TIA Portal / WinCC edition matrix is the first step toward a working solution.
Root Cause: WinCC Edition Does Not Include a PC Runtime
TIA Portal is shipped in several WinCC engineering bundles, each with progressively larger device coverage and runtime entitlements:
| TIA Portal Edition | Configuration Capability | RT Button State | PC Runtime Entitled? |
|---|---|---|---|
| WinCC Basic (TIA Portal) | SIMATIC Basic Panels (KTP / TP series) | Disabled | No |
| WinCC Comfort (TIA Portal) | Basic + Comfort Panels (TP 700 / TP 900 / TP 1200 / TP 1500 / TP 2200) | Disabled (engineering only) | No (engineering license only) |
| WinCC Advanced (TIA Portal) | Comfort Panels + WinCC Runtime Advanced PC targets | Enabled when target = PC | Yes — WinCC Runtime Advanced |
| WinCC Professional (TIA Portal) | All of the above + WinCC Runtime Professional (SCADA) | Enabled when target = PC | Yes — WinCC Runtime Professional |
| WinCC Unified (TIA Portal, V16+) | Unified Comfort Panels (MTP / TP 700–2200 Unified) + Unified PC Runtime | Enabled when target = Unified PC | Yes — WinCC Unified PC Runtime |
When the project tree targets a Basic Panel and the installed bundle is WinCC Basic, the engineering system cannot launch a runtime image because there is no PC-based runtime product licensed. The disabled RT button is the GUI expression of that licensing boundary, not a defect.
Verify the Installed TIA Portal / WinCC Edition
- Open TIA Portal.
- From the menu bar select Help → About (or Help → Installed Software on V18 and later).
- Read the Product and Version lines. Expected strings include:
SIMATIC WinCC Basic V20
SIMATIC WinCC Comfort V20
SIMATIC WinCC Advanced V20
SIMATIC WinCC Professional V20
SIMATIC WinCC Unified V20 - Cross-reference the listed WinCC Engineering Software and WinCC Runtime Software components. A WinCC Basic install will list only engineering components, no runtime.
The current shipping line as of TIA Portal V20 (released 2024) maintains this same edition separation. The behavior has been consistent from TIA Portal V13 SP1 onward.
Diagnostic Workflow: Why the RT Button Is Gray
Work through the following checks in order. Each eliminates a common cause before assuming a licensing issue.
| # | Check | Expected When Correct | Action if Not |
|---|---|---|---|
| 1 | Project compiles cleanly | No red entries in project tree, no compile errors | Right-click project → Compile → Software (rebuild all) |
| 2 | HMI device added and configured | Device visible under Devices & Networks with valid IP / Profinet name | Add HMI device matching panel part number |
| 3 | Runtime target = PC compatible | HMI device type is PC station with WinCC RT Advanced / Professional / Unified | Replace Basic Panel with a PC station or upgrade the target device |
| 4 | Runtime software installed | SIMATIC WinCC Runtime Advanced or Professional or Unified appears in Windows Programs | Install the runtime; licenses sold separately |
| 5 | Valid runtime license on PC | Automation License Manager shows a green license for the runtime package | Transfer license from USB dongle or license server |
| 6 | User has HMI engineering rights in the project | User role in TIA Portal project settings permits HMI editing | Adjust project user management / log in as engineer |
If checks 1, 2, and 3 pass but the RT button is still disabled, the cause is almost always check 3 or 4: the active HMI target cannot be hosted on the PC.
Solution Path A — Download the Project to the Physical Basic Panel
This is the canonical workflow for WinCC Basic. There is no PC runtime; the runtime image is the panel firmware.
- Compile the HMI project (right-click the HMI device → Compile → Software (rebuild all)).
- Connect the panel via Profinet / Ethernet to the engineering PC.
- In the project tree, select the HMI device and click Download to device (the green arrow icon).
- Select the detected panel interface (typically
PN/IE_1) and confirm the slot. - If prompted, transfer the panel's HMI configuration password.
- Wait for the transfer to complete. The panel will restart and load the runtime.
For older Basic Panels without an Ethernet port (e.g., OP 73 micro, TP 177 micro), use Transfer via MPI / PROFIBUS or load the project onto a USB stick and use the panel's Service → Download menu.
Solution Path B — Enable PC Runtime with WinCC Advanced or Professional
When the application genuinely needs a PC-based HMI (longer trend views, multiple simultaneous connections, archive analysis, OPC UA server, etc.), the engineering environment must be upgraded.
Step-by-step upgrade
- Obtain a SIMATIC WinCC Runtime Advanced or Runtime Professional license. These are sold separately from the engineering bundle. Common ordering data:
-
6AV2104-0AA04-0AA0— WinCC Runtime Advanced V20, 16384 PowerTags -
6AV2105-0AA04-0AA0— WinCC Runtime Professional V20, 16384 PowerTags -
6AV2107-0AA04-0AA0— WinCC Runtime Unified V20, 5000 PowerTags
-
- Install the matching WinCC runtime package on the target PC.
- Open the TIA Portal project and add a new device: PC station → SIMATIC HMI Station → WinCC Runtime Advanced or WinCC Runtime Professional (or Unified PC for V16+ Unified projects).
- Copy the screens, tags, alarms, and scripts from the Basic Panel to the PC station, or rebuild them. Note: WinCC Basic project files can be opened in WinCC Comfort/Advanced, but screen objects may need recompilation.
- Compile the new PC station and click the RT button in the toolbar. The button is now enabled because the HMI target type supports PC runtime.
- The runtime opens in a window on the engineering PC. Use the same RT button to stop it.
Solution Path C — Use WinCC Unified with HMI Monitor Client
For new projects (TIA Portal V17 and later), WinCC Unified is the recommended HMI platform. It includes a true PC runtime and a dedicated observer role: the HMI Monitor Client.
The HMI Monitor Client role is a user-management permission that grants read-only access to the runtime. It is purpose-built for production supervisors, quality engineers, and commissioning staff who must observe the process without being able to disturb it.
| Attribute | HMI Monitor Client (WinCC Unified) |
|---|---|
| Purpose | Monitor and analyze the running process without influencing the PLC |
| Write Access | Disabled (read-only) |
| Typical Operator Action | View screens, trends, alarms, audit logs |
| Configured in | TIA Portal → Project tree → Security → Users and Roles |
| Runtime entitlement | Unified PC Runtime or Unified Comfort Panel |
| Minimum TIA Portal | V17 (V20 recommended) |
Reference documentation is published in the official Siemens TIA Portal Help: HMI Role 'HMI Monitor Client' (RT Unified).
Alternative: Use the Simulator Instead of the RT Button
The RT button is distinct from the Simulator button (often shown as a triangle with a small magnifying glass). The Simulator launches a virtual PLC inside the engineering PC and is fully available in WinCC Basic. It is the proper tool for offline functional testing of screen navigation, tag animation, and alarm triggering when no PLC is available.
- Open the HMI project.
- Select Online → Simulation → Start (or click the Simulator icon).
- A separate window labeled WinCC Runtime Simulator launches. The Basic Panel screens render exactly as on hardware.
- Use the simulator's tag table to drive input values; screens react in real time.
This works in WinCC Basic because the simulator does not launch the runtime — it only simulates the PLC side of the connection.
Edition-Specific Tool Behavior Summary
| Action Available | WinCC Basic | WinCC Comfort | WinCC Advanced | WinCC Professional | WinCC Unified |
|---|---|---|---|---|---|
| Configure Basic Panel | Yes | Yes | Yes | Yes | Limited (Unified panels only) |
| Configure Comfort Panel | No | Yes | Yes | Yes | Limited (Unified panels only) |
| Simulator button | Yes | Yes | Yes | Yes | Yes |
| RT button (Basic Panel target) | Disabled | Disabled | Disabled | Disabled | N/A |
| RT button (PC RT Advanced target) | Not supported | Not supported | Enabled | Enabled | Not supported |
| RT button (PC RT Professional target) | Not supported | Not supported | Not supported | Enabled | Not supported |
| RT button (Unified PC target) | Not supported | Not supported | Not supported | Not supported | Enabled |
| HMI Monitor Client role | No | No | No | No | Yes (V17+) |
Verification Checklist
Confirm the issue is resolved after each solution path:
- Path A (download to panel): Panel boots to the configured start screen, online indicator turns blue, tags from the PLC update live.
- Path B (PC runtime): Clicking the RT button opens a runtime window within 5–15 seconds; the project title bar shows the configured HMI name.
- Path C (Unified monitor client): A user logged in with the Monitor Client role sees live screens but cannot write tags. Attempting to modify a tag returns "No write authorization".
- Simulator: Changing a simulated tag value in the simulator's tag table updates the screen within 250 ms (default acquisition cycle).
Common Pitfalls
| Pitfall | Symptom | Fix |
|---|---|---|
| Project upgraded from V13 with old HMI target | RT button still grayed despite Advanced install | Delete and re-add the HMI device as PC station |
| Mixing Basic Panel screens with PC station in same project | RT button is partially enabled | Right-click HMI device → Change device / type or split into two TIA projects |
| Demo / trial license expired | Runtime window opens then closes after 2 minutes | Renew license through ALM or activate full license |
| User account lacks "Operate" right | Runtime opens but controls are disabled | Adjust role permissions in TIA Portal project |
| Antivirus blocks runtime service | RT button appears enabled, click does nothing | Add WinCC service exceptions to Windows Defender |
Firmware / Software Compatibility Notes
When commissioning real hardware, pair the TIA Portal version with the panel firmware image installed on the device. Mismatches are a separate class of bug (typically "Incompatible firmware version" dialog during download).
| TIA Portal Version | Basic Panel FW Recommended | Unified Panel FW Recommended |
|---|---|---|
| V18 | V18.0.x | V18.0.x |
| V19 | V19.0.x | V19.0.x |
| V20 | V20.0.x | V20.0.x |
Firmware can be updated on the panel via Control Panel → Service → OS Update or remotely via TIA Portal's Online → HMI Device Maintenance → Update Firmware.
Related Documentation
- Siemens Industry Online Support — TIA Portal documentation hub
- HMI Role 'HMI Monitor Client' (RT Unified) — TIA Portal V20
Why is the RT button grayed out in TIA Portal WinCC Basic?
WinCC Basic does not include a PC runtime product. The RT button launches a PC-based runtime image; because none is licensed in WinCC Basic, the button is permanently disabled. To enable it, either install WinCC Runtime Advanced / Professional / Unified on the PC and add a matching PC station, or download the project to the physical Basic Panel instead.
Can I run a Basic Panel runtime on the PC with WinCC Advanced?
No. PC Runtime targets are emulated as WinCC Runtime Advanced, Professional, or Unified images — they do not replicate a Basic Panel. To test on a PC, you must add a PC station with a compatible runtime type and port the screens, or use the Simulator instead.
What is the difference between the Simulator and the RT button?
The Simulator starts a virtual PLC inside TIA Portal so the configured HMI screens can be exercised offline. The RT button launches the actual HMI runtime on the PC, requiring a WinCC runtime license and a PC station target. WinCC Basic supports the Simulator but not the RT button.
Which WinCC edition do I need to enable the RT button?
For PC Runtime Advanced you need WinCC Advanced (TIA Portal). For PC Runtime Professional you need WinCC Professional. For Unified PC Runtime (V17+) you need the WinCC Unified engineering bundle. The corresponding runtime license must also be installed and active in the Automation License Manager.
What is the HMI Monitor Client role in WinCC Unified?
It is a user-management role introduced in TIA Portal V17 that grants read-only access to the runtime. Users with this role can view screens, trends, and alarms on a Unified Comfort Panel or Unified PC Runtime without being able to write tags, change setpoints, or otherwise affect the process. Configuration is in Project tree → Security → Users and Roles.