Resolving STEP 7 V5.6 Install Error: OEM2 Conflict on Windows 10

Problem Summary

Engineers maintaining mixed-vintage SIMATIC fleets frequently encounter a hard-block when attempting to install STEP 7 V5.6 on a Windows 10 workstation that already runs TIA Portal V16 or has had SINAMICS commissioning tools installed. The setup wizard aborts with a dialog similar to:

"STEP 7 cannot be installed on top of an existing STEP 7 V5.7 OEM2 installation. Please uninstall the OEM version before continuing."

The setup then exits silently, leaving no error log in the user-visible channel. The root cause is rarely the TIA Portal install itself; the real conflict is a stripped-down OEM build of STEP 7 that was placed on the workstation as a dependency of a drive commissioning tool such as SIMATIC STARTER, SINAMICS Startdrive, or a third-party S7 plug-in.

This reference documents the OEM conflict, the audit procedure to identify the offending component, the clean removal sequence, the correct installer selection between SIMATIC_STEP7_V56_SP2 and STEP7_PROFESSIONAL_2017_SR2, and the coexistence rules that allow STEP 7 V5.6 and TIA Portal V16 to share a single engineering workstation.

Root Cause: The OEM Version Conflict

Siemens ships a sub-licensed version of STEP 7 internally referred to as the OEM build. The OEM build is functional for the limited scope of its host product (typically programming SINAMICS drives in STARTER) but carries the same installer fingerprint as a full STEP 7. The OEM build commonly registers itself as one of the following:

Because the OEM setup writes registry keys under HKLM\SOFTWARE\Siemens\Automation\InstalledSW and files under %ProgramFiles%\Siemens\Automation, the full STEP 7 V5.6 installer interprets these artifacts as a higher-version installation and refuses to proceed. The reported version string "V5.7 OEM2" reflects the internal build number of the Startdrive/STARTER bundle, not a public STEP 7 release — STEP 7 V5.6 was the last classic-line release and no public "V5.7" exists.

Affected Installers and Software Components

STEP 7 V5.6 exists in several installer flavors. Selecting the wrong one will reproduce the OEM2 block or trigger a separate "incompatible base version" warning.

The Professional 2017 SR2 bundle is the preferred choice when working alongside TIA V16 because it shares the same SP2 baseline and avoids version-skew issues between STEP 7, S7-GRAPH, and S7-SCL.

Pre-Installation System Audit

Before any uninstall begins, capture a snapshot of every Siemens-related entry currently on the workstation. This prevents accidental removal of TIA Portal or licensed safety packages.

1. Open Control Panel → Programs and Features (or appwiz.cpl).
2. Filter by publisher Siemens AG and screenshot the list.
3. Open regedit as administrator and export:
   • HKLM\SOFTWARE\Siemens\Automation
   • HKLM\SOFTWARE\Wow6432Node\Siemens\Automation
   • HKCU\SOFTWARE\Siemens\Automation
4. Run from an elevated command prompt: wmic product where "vendor like 'Siemens%'" get name,version,vendor /format:list > siemens_audit.txt
5. List the contents of %ProgramFiles%\Siemens\Automation and %ProgramFiles(x86)%\Siemens\Automation.

Tag each entry in the audit as one of the following categories so the removal step targets only OEM components:

Removing OEM STEP 7 Components

Execute the removal in the order shown. The order matters: removing STARTER first triggers its built-in cleanup of the OEM STEP 7 dependency, which is more thorough than removing the OEM entry in isolation.

1. Uninstall STARTER via Control Panel. Allow the uninstaller to complete; do not interrupt. If a reboot is requested, perform it before continuing.
2. Uninstall SINAMICS Startdrive if present. Even if STARTER is not installed, a standalone Startdrive package may have placed an OEM2 build.
3. Remove residual OEM entries. Re-open Programs and Features and look for entries named STEP 7 OEM, STEP 7 V5.x OEM, or any line whose Version column begins with 5.7.x. Uninstall each.
4. Clear the registry fingerprints. Delete the keys:
   • HKLM\SOFTWARE\Siemens\Automation\InstalledSW\STEP7
   • HKLM\SOFTWARE\Wow6432Node\Siemens\Automation\InstalledSW\STEP7
   • HKLM\SOFTWARE\Siemens\Automation\InstalledSW\STARTER
5. Remove leftover folders. Delete %ProgramFiles%\Siemens\Automation\STEP7_OEM and %ProgramFiles(x86)%\Siemens\Automation\STEP7_OEM if present.
6. Reboot to flush file locks and service registrations.

Selecting the Correct STEP 7 V5.6 Installer

After the workstation is clean, choose the installer that matches your project scope:

Both installers are delivered as 2.x GB ZIP archives from Siemens Industry Online Support. After extraction, right-click setup.exe and choose Run as administrator; a non-elevated launch is the most common cause of a silent exit that mimics the OEM2 error.

Clean Installation Procedure

1. Disable antivirus real-time scanning for the duration of the install; some suites quarantine S7winMM.dll and break the install halfway.
2. Extract the ZIP to a local path with at least 6 GB free (avoid external USB drives and OneDrive-synced folders — both corrupt long-path S7 components).
3. Right-click setup.exe → Run as administrator.
4. Accept the license transfer ID prompt. If the installer halts here, verify %ProgramData%\Siemens\Automation\LicenseKey is writable.
5. Choose Install rather than Modify; a Modify launch against a partially cleaned workstation reproduces the OEM2 block.
6. When prompted, select Typical installation unless you specifically need a custom component map.
7. Allow the installer to register S7DOS, s7oiehsx, and SIMATIC IEPG Help services.
8. Reboot when prompted, even if the prompt is unchecked.
9. Re-launch SIMATIC Manager once before connecting to a target to confirm license registration.

TIA Portal V16 Coexistence

STEP 7 V5.6 and TIA Portal V16 can coexist on the same engineering workstation with no functional penalty when the following rules are observed:

• Project conversion is one-way. A TIA Portal V16 project cannot be opened in SIMATIC Manager. A SIMATIC Manager project can be migrated to TIA with Migrate Project, but the original archive must be retained.
• PG/PC interface assignments are independent. STEP 5/STEP 7 V5.6 uses S7DOS routing through the Set PG/PC Interface control panel applet. TIA V16 uses the TIA channel configuration. Both can be configured simultaneously without conflict.
• Licenses are tracked separately. A license on a parallel USB dongle or in the Siemens License Server covers one product line only; co-installation does not transfer license entitlements.
• Symbolic imports through OPC. If a project bridges the two environments via OPC DA/UA, install the TIA-side OPC UA server first, then enable the SIMATIC NET OPC bridge inside STEP 7 V5.6 last, to avoid registration order conflicts.

Registry and File System Cleanup

If the OEM block persists after the standard uninstall sequence, inspect the registry and the file system directly.

Registry keys to remove

HKLM\SOFTWARE\Siemens\Automation\InstalledSW\STEP7_OEM
HKLM\SOFTWARE\Siemens\Automation\InstalledSW\OEM2
HKLM\SOFTWARE\Wow6432Node\Siemens\Automation\InstalledSW\STEP7_OEM
HKCU\SOFTWARE\Siemens\Automation\STEP7_OEM

Folders to remove

%ProgramFiles%\Siemens\Automation\STEP7_OEM
%ProgramFiles(x86)%\Siemens\Automation\STEP7_OEM
%ProgramData%\Siemens\Automation\OEM
%CommonProgramFiles%\Siemens\Automation\OEM

Service cleanup

Open services.msc and stop+disable any of the following if they remain after uninstall:

• s7oiehsx
• S7DOS Helper
• SIMATIC STARTER Service

Installation Verification

After a successful install, perform the following verification battery before declaring the workstation operational:

1. Launch SIMATIC Manager. The File → Open dialog should list the default sample projects under ...\Siemens\Automation\S7\S7proj.
2. Open Set PG/PC Interface. Confirm at least one TCP/IP or MPI adapter is enumerated without yellow warning triangle.
3. Launch S7-PLCSIM (if Professional bundle installed). Start an empty S7-300 station in PLCSIM and download the hardware configuration from SIMATIC Manager.
4. Verify license status: SIMATIC Manager → Help → About → License should show a green check for all installed packages.
5. Open TIA Portal V16 and confirm the existing TIA project still opens without prompting for re-license.
6. Run sfc /scannow from an elevated command prompt and confirm no integrity violations were introduced by the Siemens service installs.

Troubleshooting Matrix

Frequently Asked Questions