Resolving OS Project Download Hangs and SQL Database Attachment Failures in PCS 7

When downloading an OS project from an Engineering Station (ES) to an OS Server succeeds in copying the files but subsequently hangs or generates an error when opening the project, the failure is caused by insufficient SQL Server database permissions, Windows user credential mismatches, or network adapter binding conflicts in Simatic Shell. To resolve this issue: 1. Ensure the Windows user logged into the ES belongs to the 'SIMATIC HMI' and 'Administrators' local groups on the target OS Server and possesses SQL sysadmin privileges; 2. Configure identical Windows usernames and passwords across all stations; 3. Verify in Simatic Shell that the primary Terminal Bus network adapter is selected with encrypted communications enabled; and 4. Restart the WinCC SQL Server instance on the target server.

Executive Summary

The engineering workflow in SIMATIC PCS 7 relies on downloading compiled Human-Machine Interface (HMI) projects from the central Engineering Station (ES) to target OS Servers across the industrial Terminal Bus. A widespread and frustrating operational roadblock occurs when the file copy phase reaches 100% completion, but the process stalls indefinitely or aborts with error codes during the final project opening phase ('Opening project on target station...'). When this happens, WinCC Explorer fails to launch the newly downloaded project on the server. This article details the internal mechanics of project transfer, identifies the underlying SQL database attachment and Windows security prerequisites, and provides a proven diagnostic procedure to restore seamless OS downloads.

Architecture and Fundamental Mechanics

OS Project Download Pipeline, SQL Database Attachment, and Simatic Shell Mechanics:

The Two-Phase OS Download Pipeline:
Phase 1 (File Copy): The ES establishes a Windows SMB network share connection to the target server's shared folder (TargetDirectory\ProjectName). It transfers project metadata (.mcp), screen graphics (GraCS), and the master WinCC SQL Server database files (.mdf, .ldf).
Phase 2 (Remote Project Open & SQL Attachment):
- Following file transfer, the ES invokes remote COM/DCOM calls to CCProjectMgr.exe on the target OS Server.
- CCProjectMgr commands the local Microsoft SQL Server instance (WinCC) to attach the downloaded database files and updates the project's internal computer name in the SQL database to match the physical server name.
- If this remote attachment fails, the download dialog hangs indefinitely or aborts with an error such as 'Cannot open project'.
Root Cause 1: Windows Security and SQL Server User Rights:
The Windows user account initiating the download on the ES must exist on the target OS Server with an identical username and password (unless managed under an Active Directory domain).
On the OS Server, this user account must be an explicit member of the local Administrators group and the SIMATIC HMI group.
During database attachment, SQL Server validates file access tokens. If the user lacks local administrative rights, SQL Server denies file access, locking CCProjectMgr.
Root Cause 2: Simatic Shell Configuration & Terminal Bus Binding:
The internal discovery service Simatic Shell coordinates remote engineering actions.
If Simatic Shell on either the ES or OS Server is bound to the wrong network adapter (e.g. an auxiliary plant bus card or unconnected wireless adapter), remote RPC/DCOM calls cannot complete, causing the finalization step to time out.
Root Cause 3: Orphaned SQL Locks and Corrupted Cache:
If a previous download crashed, the WinCC SQL Server service may retain exclusive read/write locks on orphaned .mdf files in the project directory, preventing the new database from attaching.

Step-by-Step Implementation Procedure

Align Windows User Accounts and Security Group Memberships:
* On both the ES and OS Server, open Computer Management -> Local Users and Groups -> Users.
* Ensure that an identical administrative user (e.g. SimaticAdmin) exists on both machines with the exact same password.
* On the target OS Server, open Groups:
- Add SimaticAdmin to the Administrators group.
- Add SimaticAdmin to the SIMATIC HMI group.
- Log off and log back in on both stations to update access tokens.
Verify Simatic Shell Terminal Bus Network Settings:
* On the target OS Server, open Windows File Explorer and click Network -> Simatic Shell (or This PC -> Simatic Shell).
* Right-click Simatic Shell and select Settings....
* Verify that the selected network adapter is the physical network card connected to the Terminal Bus.
* Under Encrypted Communication, ensure that the encryption settings and PSK (Pre-Shared Key) match between the ES and OS Server.
* Repeat this check on the Engineering Station.
Clear Stale WinCC SQL Database Locks:
* On the target OS Server, close WinCC Explorer.
* Open Windows Command Prompt as Administrator.
* Execute net stop MSSQL$WINCC followed by net start MSSQL$WINCC (or restart the server).
* Navigate to the target project directory on the OS Server; verify that no temporary .tmp or locked database files exist.
Verify Shared Folder Permissions on the Target OS Server:
* Locate the destination project folder on the OS Server.
* Right-click the folder -> Properties -> Sharing -> Advanced Sharing.
* Under Permissions, grant Full Control to Everyone and SIMATIC HMI.
* Under the Security tab, grant Full Control to Administrators and SIMATIC HMI.
Re-execute the OS Download from SIMATIC Manager:
* On the ES, open SIMATIC Manager.
* Right-click the OS Server node -> PLC -> Download.
* Select Entire OS (or Changes if previously downloaded).
* Observe the progress: file copy completes, followed by successful project opening and computer name adaptation.

Verification

In SIMATIC Manager on the ES, verify that the download dialog completes with the message 'Download completed successfully' without error popups.
On the target OS Server, verify that WinCC Explorer launches automatically (or opens the project cleanly upon manual launch).
Inspect WinCC Explorer title bar; verify that the project name matches and the status indicates active/ready.
Activate Runtime on the OS Server; verify that process graphics and tag connections load immediately.

Limitations and Operational Precautions

Downloading to a running OS Server is only permitted if 'Download Changes' (delta download) is supported and active; an Entire Download requires deactivating WinCC Runtime on the target server. In redundant OS configurations, always download to the Standby server first, verify runtime synchronization, and then download to the Master server to prevent process visualization blackouts.

Engineer FAQ

Why does the OS download hang at the very end after copying files?

Because the ES cannot remotely invoke CCProjectMgr.exe on the OS Server to attach the WinCC SQL database due to missing permissions or network adapter mismatches in Simatic Shell.