Resolving TIA Portal V14 Network Drive Missing in Admin Mode

1. Problem Overview

When TIA Portal V14 (Update 1 / SP1) or STEP 7 V5.6 is launched with the Run as administrator option on a Windows 10 engineering workstation, the following symptoms appear immediately:

• Mapped network drives (UNC paths such as \\PROJ-FS\TIA\ProjectLibrary) are missing from the project navigation tree.
• Network locations that were visible under the standard user token disappear from This PC > Network Locations.
• Secondary internal hard disks mapped through SMB shares on a server are invisible to the TIA Portal project wizard.
• The same paths remain visible when the engineering tool is launched without elevation (no UAC consent prompt).

The behavior is not a TIA Portal bug, not a STEP 7 installation defect, and not a license-server issue. It is the documented consequence of how Windows User Account Control (UAC) splits the user's logon token and how SMB drive mappings bind to the unelevated (filtered) token by default.

2. Root Cause: UAC Token Splitting and Linked Connections

Windows uses two access tokens for members of the local Administrators group when UAC is enabled:

Network drive letters created under the standard token are attached to the user's logon session inside the \Device\LanmanRedirector device namespace. When a process elevates, Windows builds a new logon session for the elevated token and the redirected drives are not propagated. TIA Portal V14 inherits the elevated token of its parent process, so the mapped drives vanish.

Microsoft documents this exact behavior in KB 3035277 — Mapped drives are not available from an elevated prompt when UAC is configured to prompt for credentials. The KB applies to Windows 7, Windows 8, Windows 8.1, and Windows 10.

3. Affected Software and Operating-System Matrix

Before applying the registry fix, validate the engineering workstation meets Siemens' published OS support matrix. Running TIA Portal or STEP 7 on an unsupported Windows 10 build can cause the same symptoms and must be ruled out first.

If the workstation is running Windows 10 Home and the project requires TIA Portal Professional features, upgrade to Pro or Enterprise before troubleshooting further. Confirm the installed build with winver and the edition with the registry value HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\EditionID.

4. Solution A — Enable the EnableLinkedConnections Registry Value

This is the supported, Microsoft-documented fix. The DWORD forces Windows to expose the standard-user drive mappings inside the elevated session as well.

4.1 Manual Procedure

1. Open the Run dialog (Win + R), type regedit, and press Enter.
2. Accept the UAC prompt (this is the only time elevation is correct — for editing the registry).
3. Navigate to:
   HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
4. Right-click > New > DWORD (32-bit) Value.
5. Name the value exactly: EnableLinkedConnections
6. Set the value data to 1 (decimal).
7. Click OK and close regedit.
8. Restart the workstation, or sign out and back in. A simple logoff/logon is sufficient because the value is read at logon when the user profile is created.

4.2 Command-Line Equivalent

For fleets of engineering PCs, deploy the value through a script run as Administrator:

reg add "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" \
  /v EnableLinkedConnections /t REG_DWORD /d 1 /f

Or via PowerShell (elevated):

$path = 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System'
New-ItemProperty -Path $path -Name 'EnableLinkedConnections' `
  -PropertyType DWord -Value 1 -Force

4.3 Effect of the Value

5. Solution B — Group Policy Deployment (Domain Environments)

In a Siemens engineering domain (typical for plant-floor engineering PCs joined to plant.local or similar), push the setting through a GPO so every workstation picks it up consistently.

1. Open Group Policy Management Console on a domain controller.
2. Edit (or create) a GPO scoped to the engineering workstation OU, for example OU=EngineeringPCs,DC=plant,DC=local.
3. Navigate to Computer Configuration > Preferences > Windows Settings > Registry.
4. Right-click > New > Registry Item.
5. Configure the item exactly as follows:
   • Hive: HKEY_LOCAL_MACHINE
   • Key Path: SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
   • Value name: EnableLinkedConnections
   • Value type: REG_DWORD
   • Value data: 1
6. Click Apply and OK.
7. Force a refresh on the target PC: gpupdate /force, then reboot.

6. Solution C — Re-map Drives Inside the Elevated Session

If modifying the registry is not acceptable (for example, a locked-down corporate image), re-establish the mappings from inside the elevated shell. This is a per-session workaround, not a permanent fix.

1. Open Command Prompt (Admin) or Windows PowerShell (Admin).
2. Use net use to remap each drive:r>

   net use Z: \\PROJ-FS\TIA\ProjectLibrary /persistent:yes
   net use Y: \\PROJ-FS\TIA\Libraries /persistent:yes
   

3. Launch TIA Portal V14 from the elevated prompt:

   "C:\Program Files\Siemens\Automation\Portal V14\Bin\S7TIA.exe"
   

Drives mapped this way are visible only until the elevated process exits or the session is terminated. Each new elevation requires re-mapping. This approach is acceptable for short troubleshooting sessions but not for daily engineering work.

7. Solution D — Configure TIA Portal to Auto-Elevate Without a Re-Map

TIA Portal V14 SP1 ships with a compatibility manifest that does not request requireAdministrator for normal project operations. Confirm the manifest has not been altered by a third-party installer.

1. Browse to C:\Program Files\Siemens\Automation\Portal V14\Bin\.
2. Right-click S7TIA.exe > Properties > Compatibility tab.
3. Clear the checkbox Run this program as an administrator if it is set.
4. Click Apply.

For day-to-day use, run TIA Portal from the standard token and only elevate the specific tool (for example, Start > Automation License Manager) that genuinely needs the elevated context.

8. Verification Procedure

Apply any of the solutions above, then run the following validation sequence to confirm the engineering workstation behaves correctly:

1. Confirm the registry value:

   reg query "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" /v EnableLinkedConnections
   

   Expected output contains 0x1.
2. Confirm the mapped drive exists in both sessions:
   • Open a non-elevated cmd, type net use, confirm Z: \\PROJ-FS\TIA\ProjectLibrary.
   • Open an elevated cmd (Run as administrator), type net use, confirm the same entry.
3. Launch TIA Portal V14 elevated: Right-click the desktop shortcut, choose Run as administrator.
4. In TIA Portal, open Project > Open. The network path of the mapped drive should be selectable in the file picker.
5. Open the Project tree > Project library > External libraries dialog. Drives containing global libraries must be listed.
6. Open STEP 7 V5.6 elevated. Choose File > Open > User Project. Network-resident projects must be visible.
7. Open the Automation License Manager (ALM). Confirm the license server is reachable.

If any of the steps above still show missing drives, revisit Section 6 to confirm the registry change survived a Group Policy refresh and the workstation was rebooted.

9. Common Edge Cases and Field Findings

10. Security Considerations

• Do not disable UAC as an alternative — disabling UAC removes the filtered token entirely, which is a far larger attack-surface change.
• Restrict who can set the value to local administrators only. The value is a per-machine setting under HKLM.
• If your plant network enforces Network Access Protection or 802.1X, confirm that the elevated session still authenticates identically. In most domains, the same machine-account credentials are used for SMB, so the re-authentication is transparent.
• Avoid storing long-lived credentials in cmdkey. Use Windows Credential Manager with a service account that has a scheduled rotation.

11. Programmatic Sanity Check for Administrators

The following PowerShell snippet is suitable for the engineering team's configuration-management script. It returns OK when the fix is in place, MISSING when it is not, and exits with a non-zero code in the latter case — useful for SCCM / Intune compliance baselines.

$value = Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System' `
  -Name 'EnableLinkedConnections' -ErrorAction SilentlyContinue
if ($value.EnableLinkedConnections -eq 1) {
  Write-Output 'OK'
  exit 0
} else {
  Write-Output 'MISSING'
  exit 1
}

12. Frequently Asked Questions