How to Resolve PCS 7 OS Download Freezes and 'No or Invalid Project Context, ASO Cannot Work' Errors

How to Resolve PCS 7 OS Download Freezes and 'No or Invalid Project Context, ASO Cannot Work' Errors

To resolve the SIMATIC PCS 7 error 'No or invalid Project context, ASO cannot work correct' and prevent project transfer freezes when downloading an OS from the Engineering Station (ES) to an OS Server, engineers must correct network station addressing, network adapter binding priority, and DCOM security permissions. This fault occurs when the ES attempts to establish a remote Data Source Name (DSN) connection across Windows network shares, but fails because the target OS path was configured with an IP address instead of the official Windows NetBIOS computer name, or because the Terminal Bus network adapter is not at the highest priority in the Windows adapter binding order. The resolution requires using valid NetBIOS computer names, prioritizing the Terminal Bus NIC in network settings, configuring Simatic Shell, and running the Siemens Security Controller.

Table of Contents

• Root Causes: Why Remote DSN Project Context Fails
• Target Path Configuration: NetBIOS Computer Name vs IP Address
• Network Adapter Binding Order and Simatic Shell Priority
• Step-by-Step Resolution: Security Controller, Rights, and DEP
• OS Download Diagnostics and Failure Checklist Matrix
• Verification
• Limitations and Operational Precautions
• Engineer FAQ
• Technical References
• Related Articles
• Related Tags

Root Causes: Why Remote DSN Project Context Fails

When transferring an OS project from the Engineering Station to an OS Server or OS Client via SIMATIC Manager (PLC -> Download), the system does not simply copy flat files across SMB.

Instead, the process executes a complex remote database mounting routine:
1. The ES establishes a connection over the Windows network share (<Shared_Project_Folder>).
2. The Engineering Station's Automation Server Object (ASO) requests the target machine to mount the project database (.mdf/.ldf) and register a system Data Source Name (DSN).
3. If the ES cannot resolve the target station's DSN endpoint over the network card, the download freezes indefinitely on 'Opening WinCC project...' or aborts with:
'No or invalid Project context, ASO cannot work correct'.

This failure indicates that the network path, network adapter priority, or Windows security permissions are preventing the remote SQL Server and ASO components from establishing a mutual security context.

Target Path Configuration: NetBIOS Computer Name vs IP Address

A critical engineering rule in SIMATIC PCS 7 is that IP addresses must never be used in target OS download paths:

• In SIMATIC Manager, right-click the OS object -> Object Properties -> Target OS and Standby OS.
• The target path must reference the Windows computer name via a UNC share:
  \<Target_Computer_Name>\<Share_Name>\<Project_Name>.mcp
• Using an IP address (e.g., \192.168.1.10\Share\...) causes ASO to fail. WinCC SQL Server communication components rely strictly on Windows NetBIOS and DNS hostname resolution to authenticate Kerberos and NTLM tokens. Using an IP address bypasses Windows authentication contexts, resulting in the 'Invalid Project Context' error.

Network Adapter Binding Order and Simatic Shell Priority

On workstations equipped with multiple network cards (Terminal Bus, Plant Bus, and Redundancy Link), the operating system must know which network interface handles administrative SIMATIC traffic:

1. Windows Network Adapter Binding Order

• Open Control Panel -> Network and Internet -> Network Connections.
• Press Alt -> Advanced -> Advanced Settings (or configure interface metrics via PowerShell):
• The Terminal Bus network adapter must reside at the very top of the binding order (lowest metric), ensuring that all inter-station DCOM and SQL requests route through the Terminal Bus.

2. Simatic Shell Configuration

• In Windows Explorer, expand the This PC tree and locate Simatic Shell.
• Right-click Simatic Shell -> Settings / Properties.
• In the network adapter selection dropdown, ensure the Terminal Bus network card is explicitly selected.
• If multicast encryption is enabled, ensure the encryption passphrase matches identically across all participating stations in the plant.

Step-by-Step Resolution: Security Controller, Rights, and DEP

Follow this comprehensive troubleshooting sequence to restore clean OS downloads:

Step 1: Align Hostnames and User Accounts

1. Ensure the logged-in Windows user account exists on both the ES and the target OS with the exact same username and password.
2. Add the user to the following local groups on both machines:
   * Administrators
   * SIMATIC HMI
   * SIMATIC NET
3. Verify that both stations can ping each other using their exact computer names. If not, add entries to C:\Windows\System32\drivers\etc\hosts.

Step 2: Set Folder Share and Security Permissions

1. On the target OS, share the destination folder (e.g., D:\WinCC_Projects).
2. Share Permissions: Grant Full Control to Everyone and SIMATIC HMI.
3. NTFS Permissions (Security tab): Grant Full Control to SIMATIC HMI and SYSTEM.

Step 3: Run SIMATIC Security Controller and SIMATIC Rights

1. On both the ES and OS, run Siemens Security Controller (Start -> All Programs -> Siemens Automation -> Security Controller) and click Repeat Settings.
2. Run the SIMATIC Rights utility (located on the PCS 7 installation DVD under Additional Products\SIMATIC Rights\) on the target shared folder to enforce proper DCOM ACLs.

Step 4: Verify Data Execution Prevention (DEP)

1. In Windows System Properties -> Advanced -> Performance Settings -> Data Execution Prevention.
2. Ensure DEP is configured to: 'Turn on DEP for essential Windows programs and services only'.
3. Restart both workstations and re-execute the OS download from SIMATIC Manager.

OS Download Diagnostics and Failure Checklist Matrix

The following table outlines the diagnostic checkpoints, error symptoms, and corrective actions:

Maintaining disciplined network naming and security permissions ensures rapid, error-free engineering downloads.

Verification

To verify that the OS download succeeds:
1. In SIMATIC Manager, initiate PLC -> Download -> Entire OS (or changes only).
2. Verify that the progress dialog cleanly transitions past 'Connecting to target system' and 'Opening WinCC project' without hanging.
3. Confirm that file copying completes and the progress bar reaches 100%.
4. On the target OS Server, open WinCC Explorer; verify that the project opens without error prompts and displays the local computer name in the title bar.

Limitations and Operational Precautions

• Never initiate an OS download across a Remote Desktop (RDP) session without the /admin or /console switch, as standard RDP sessions assign non-zero session IDs that block WinCC GUI initialization.
• Computer names must never exceed 15 characters, must not start with a digit, and must not contain hyphens or underscores.
• Do not disable the Windows Firewall completely; use the Siemens Security Controller to open required ports while preserving host security.
• In redundant systems, ensure the Standby Server is downloaded and synchronized before downloading the Master Server.

Engineer FAQ

Why does using an IP address cause 'ASO cannot work correct'?

Siemens Automation Server Object (ASO) utilizes Microsoft DCOM and Kerberos authentication. Kerberos requires fully resolved NetBIOS/DNS computer names to issue mutual authentication tickets; raw IP addresses cause security rejection.

What is the purpose of Simatic Shell?

Simatic Shell is the underlying communication layer that discovers and coordinates SIMATIC stations across the Terminal Bus using multicast broadcasts. Without proper adapter selection, stations cannot establish mutual project awareness.

Can I copy the OS project manually via USB if network download fails?

Yes, as a temporary workaround: copy the OS project folder to the target PC, open it in WinCC Explorer, update the computer name to local, close WinCC, and restart runtime.

Technical References

• SIMATIC PCS 7 Compendium Part A - Configuration Guidelines (Section 4.5 OS Configuration)
• SIMATIC PCS 7 PC Configuration and Authorization Manual
• Siemens Industry Online Support Entry 868014: Name Resolution and Network Configuration Guidelines

Related Articles

• How to Resolve WinCC OS Client Download Error 'An Error Occurred While Changing the Computer Name'
• Configuring Terminal Bus and Plant Bus Network Adapters in SIMATIC PCS 7
• How to Reset WinCC Runtime and Clear Lingering Background Processes via CCCleaner

Related Tags

• OS Download Failure
• ASO Cannot Work
• Simatic Shell
• Terminal Bus
• Target OS Assignment