Resolving WinCC v6.2 MCI32.OCX Installation Error on Windows 7

1. Problem Summary

Engineers migrating from Windows XP to Windows 7 frequently encounter a hard install failure when deploying SIMATIC WinCC V6.2 (including SP1, SP2, and the Asia/Chinese localizations). The setup routine aborts during component registration and surfaces a dialog that references MCI32.OCX. The error is not a transient file-lock issue and is not resolved by re-running the installer with elevated rights. It is a structural incompatibility between the WinCC V6.2 runtime/engineering installer and the Windows 7 user-mode component framework.

Commonly observed failure messages include:

• Error: MCI32.OCX — raised before the installation completes the "Registering components" phase.
• Component 'MCI32.OCX' failed to register (HRESULT 0x80040200 / 0x8002801C class not registered variants).
• Silent rollback: the installer returns to the splash screen, removes staged files, and reports a generic "Installation failed".
• Setup log entry Regsvr32: DllRegisterServer in MCI32.OCX failed inside %temp%\Siemens\WinCC\Setup.log.

2. What Is MCI32.OCX and Why WinCC V6.2 Needs It

MCI32.OCX is the Microsoft Media Control Interface 32-bit ActiveX control (MCI32.OCX, file version stamped 6.1.7600.x in the redistributable pool). It exposes the MSMCI32 CoClass used by WinCC for:

• Audible alarm horn playback (\<horn>.wav in the graphics designer alarm logging).
• Audio cues inside WinCC Alarm Control and WinCC Sound Control.
• Legacy camera/AVI preview paths used by the V6.2 CamControl add-on.
• Video file playback in custom C-scripts using mciSendString via the COM wrapper.

WinCC V6.2's setup calls Regsvr32 /s MCI32.OCX as part of the OS runtime prerequisites (component group "WinCC Runtime - Common Components"). The control ships in the redistributable folder \InstData\Windows\InstData\Redist\OCX of the installation media. Under Windows XP and Server 2003 the call returns S_OK. Under Windows 7 the same call returns 0x80040200 because the Multimedia Control Interface has been reclassified by Microsoft as a deprecated runtime and the dependent interfaces (IMCIPlayer2, IMCIPicture) are no longer proxied through the standard MSCTF.dll registration chain.

3. WinCC V6.x / V7.x Compatibility Matrix

The root cause of the install failure is OS-level, not media-level. The table below summarizes the officially supported Windows host operating systems for the WinCC Classic (pre-TIA Portal) runtime and engineering suite.

¹ WinCC V7.0 SP1-SP3 64-bit editions require the SIMATIC WinCC V7.0 SP3 Update 3 or later and KB2493989 host hotfix. Earlier 64-bit builds on Windows 7 are blocked by the same MCI32.OCX symptom seen on V6.2.

4. Why Direct Installation on Windows 7 Fails

Three structural changes in Windows 7 break the WinCC V6.2 installer:

1. User Account Control (UAC) manifest. The setup calls Regsvr32.exe from a non-elevated context. UAC's split-token model blocks the HKCR\CLSID write that registers the MCI32.OCX CoClass, even when the launching user is in the local Administrators group.
2. Side-by-side (SxS) assembly redirection. Windows 7 routes legacy mscoree.dll and MSCTF.dll calls through the Fusion SxS resolver. The V6.2 manifest embedded in MCI32.OCX references side-by-side assemblies (Microsoft.Windows.Common-Controls 5.82.0.0) that are not present in the Windows 7 default SxS store.
3. Removal of the 16-bit MCI thunk layer. The Multimedia Control Interface on Windows 7 is 64-bit clean but no longer ships the 32-bit winmm.dll shim used by MCI32.OCX's internal IClassFactory. Registration returns CLASS_E_CLASSNOTREG (0x80040154).

These three changes are the exact reason Siemens never issued a Windows 7 hotfix for WinCC V6.2: the fix would require re-architecting the OCX and would invalidate the existing certified PLC tag interface compatibility.

5. Pre-Installation Checklist

Before applying any of the workarounds below, validate the following on the target laptop or engineering workstation:

• Confirm the exact installed Windows build: winver must report Windows 7 SP1 (build 7601) or later. Pre-SP1 builds exhibit additional failures unrelated to MCI32.OCX.
• Confirm the bitness of the OS: 32-bit Windows 7 requires 32-bit WinCC media; 64-bit Windows 7 requires 64-bit WinCC media. Do not mix.
• Free at least 8 GB on C: for the WinCC V6.2 install footprint plus SQL Server 2005 instance.
• Disable the antivirus real-time scan on C:\Program Files\Siemens and C:\Windows\System32 during install. Some suites quarantine MCI32.OCX on copy.
• Verify .NET 3.5 SP1 and .NET 4.0 are present. WinCC V6.2 SP3+ uses a small set of .NET assemblies for the Graphics Designer add-in loader.
• Ensure the local SQLServer2005 instance is not already bound to TCP port 1433 by a third-party SQL Express install — WinCC's WinCC_CC_Exp_2005 installer refuses to start if it cannot bind port 1433.

6. Workaround A — Windows XP Mode (Recommended for Engineering Only)

Windows XP Mode is a Microsoft-provided Windows XP SP3 virtual machine that runs inside Windows 7 Professional, Enterprise, or Ultimate. It is the lowest-friction path for engineering workstations that must still edit V6.2 projects.

6.1 Prerequisites

• Windows 7 Professional, Enterprise, or Ultimate (XP Mode is not available on Home editions).
• Hardware virtualization enabled in BIOS (Intel VT-x or AMD-V). The XP Mode VHD will refuse to boot if virtualization is disabled.
• Minimum 2 GB host RAM, 3 GB recommended; 15 GB free disk for the dynamic VHD.
• Latest Windows Virtual PC and XP Mode update rollup (KB2686827, KB4019999 are the most recent cumulative patches).

6.2 Step-by-Step Setup

1. Download WindowsXPMode_en-us.exe and Windows6.1-KB958559-x64-RefreshPkg.msu (or x86) from the official Microsoft Download Center. Validate the SHA-1 hash before running.
2. Install Windows Virtual PC, then install XP Mode. Accept the default C:\Users\<user>\AppData\Local\Microsoft\Windows Virtual PC\Virtual Machines\Windows XP Mode.vhd location.
3. Boot the VM, install Virtual PC Integration Components from the Tools menu of the VM window. This enables clipboard sharing, drive redirection, and dynamic resolution.
4. Apply all Windows XP SP3 updates inside the VM, then disable automatic updates — the VM must remain on SP3 to host WinCC V6.2 reliably.
5. Map a host drive letter to the engineering project's source folder: Tools → Settings → Integration Features → Shared Folders.
6. Mount the WinCC V6.2 SP3 ISO inside the VM and launch Setup.exe. Install in the order: SQL Server 2005 Express → WinCC Runtime → WinCC Configuration. The MCI32.OCX registration now succeeds because the host is Windows XP SP3.
7. After install, apply WinCC V6.2 SP3 Update Rollup 6 (or the latest available) to resolve known stability issues.

7. Workaround B — Dedicated Virtual Machine (Recommended for Runtime)

For an isolated WinCC V6.2 runtime on Windows 7 hardware, the best path is a full hypervisor-based VM running Windows XP SP3 or Windows Server 2003 R2 as a guest. This isolates the legacy OS from the engineering host and avoids XP Mode's 90-day re-activation cycle.

7.1 Recommended Hypervisors

7.2 Step-by-Step Configuration

1. Create a Windows XP SP3 or Windows Server 2003 R2 guest with at least 2 vCPU and 4 GB RAM. WinCC V6.2 runtime requires a 2 vCPU configuration to handle alarm logging without queue overruns.
2. Assign a bridged network adapter and a static IP. NAT breaks the WinCC channel DLL for S7COMM and OPC if the channel expects to bind to a real adapter MAC.
3. Install Guest Additions / VMware Tools before installing WinCC. Reboot.
4. Set the guest power profile to High Performance. The default Balanced profile throttles the alarm logging service and triggers Alarm Logging Service: Queue Overflow events.
5. Disable Windows XP screen saver and disable hibernation. Both interact badly with the WinCC runtime pdlservice.exe process.
6. Install SQL Server 2005 Express SP3, then WinCC V6.2 SP3. The MCI32.OCX registers cleanly inside the legacy guest.
7. Configure the VM to autostart the WinCC runtime project with the host's boot. In VMware, use VM → Settings → Options → Start/Actions After Power On → Power On + Open Console; in Hyper-V, use the Automatic Start Action settings of the VM.

8. Workaround C — Upgrade to WinCC V7.0+

If the project can be migrated, the cleanest path is to upgrade the WinCC platform to V7.0 SP3 Update 3 or later, which is fully supported on Windows 7 SP1 (32-bit) and Windows Server 2008 R2 (64-bit). V7.x re-architects the MCI32.OCX dependency and replaces it with the WinCC Audio Player built on the Windows 7 Media Foundation stack.

8.1 Migration Procedure

1. On the existing XP host, open the V6.2 SP3 project and run Project → Migrate → V7.0. This produces a new .mcp project file and a migration report MigrationReport.html in the project root.
2. Open MigrationReport.html and resolve every red entry. Typical issues: deprecated C-script functions, V6.2-only channel DLLs (e.g., SIMATIC S7 Protocol Suite <= V6.2), and @ global script references.
3. Re-link any picture window that used MCI32.OCX for embedded video; switch to the WinCC Media Control ActiveX that ships with V7.x.
4. Save the migrated project, copy to the Windows 7 host, install WinCC V7.0 SP3 Update 3, then install the latest hotfix (typically WinCC_V70_SP3_Upd13.exe or newer).
5. Re-compile all C-scripts (Tools → C-Editor → Rebuild All) and re-test every alarm horn path.

9. Manual Workaround — Registering MCI32.OCX Outside the Installer

It is technically possible to copy MCI32.OCX from the WinCC V6.2 media and register it manually, but this only unblocks the "Registering components" phase of the installer. The remaining V6.2 components will still fail on Windows 7 because of the SxS and winmm.dll issues described in Section 4. Treat this as a diagnostic step, not a solution.

1. Extract MCI32.OCX from the ISO: 7z e WinCC_V62_SP3.iso MCI32.OCX -oC:\Temp\OCX\.
2. Copy to the correct system directory:
   • 32-bit Windows 7: copy C:\Temp\OCX\MCI32.OCX %SystemRoot%\System32\
   • 64-bit Windows 7: copy C:\Temp\OCX\MCI32.OCX %SystemRoot%\SysWOW64\
3. Open an elevated Command Prompt.
4. Register the control:
   • 32-bit: regsvr32 %SystemRoot%\System32\MCI32.OCX
   • 64-bit: %SystemRoot%\SysWOW64\regsvr32 %SystemRoot%\SysWOW64\MCI32.OCX
5. If registration succeeds with DllRegisterServer in MCI32.OCX succeeded, proceed with the WinCC setup. If it returns 0x80040200 or 0x8002801C, abandon this path and use Workaround A, B, or C.

10. Diagnostic and Verification Matrix

11. Best-Practice Recommendations

• Treat the MCI32.OCX error as a compatibility sentinel. If it appears, the entire V6.2 stack is incompatible with the host OS. Do not try to patch around it.
• Maintain a Windows XP SP3 or Server 2003 R2 reference image (gold image) with WinCC V6.2 SP3 + latest update rollup pre-installed. Deploy it as a VM on every modern engineering workstation.
• Move runtime platforms to WinCC V7.4 SP1 or V7.5 SP2 wherever project scope allows. Both ship native Windows 7 SP1 (32-bit and 64-bit) support and resolve the MCI32.OCX dependency at the source.
• Disable Windows 7 UAC for engineering VMs that run legacy installers. UAC split-token is the silent cause of many "ghost" registration failures in addition to MCI32.OCX.
• Keep a copy of the WinCC V6.2 SP3 update rollup and license key offline. A license server outage on a Windows 7 host can be unrecoverable if the V6.2 license dongle drivers are not preinstalled.
• For long-term support, plan a multi-year migration to WinCC Professional (TIA Portal) V17 or later, which drops the legacy OCX stack entirely.

12. Frequently Asked Questions