SIMATIC Manager Multiproject Deletion Behavior - Preserving Subprojects and Master Libraries

When you delete a Multiproject in SIMATIC Manager, only the top-level multiproject database and directory container (.s7m structure) are removed; the underlying subprojects (AS, OS) and Master Data Libraries are intentionally retained on disk. This behavior is by design to protect engineering assets in modular PCS 7 environments. A Multiproject serves as an organizational framework linking independent STEP 7 projects for cross-controller communication and centralized OS compilation. Because subprojects can be decoupled, reassigned, or reused across different multiprojects via 'Multiproject -> Insert into Multiproject', SIMATIC Manager prevents accidental deletion of project files. To permanently delete subprojects, you must delete each project individually within SIMATIC Manager or manually remove their folders from the Windows filesystem.

Executive Summary

In SIMATIC PCS 7 engineering environments, plant architectures are organized as Multiprojects containing multiple automation stations (AS), operator stations (OS), and a centralized Master Data Library. When an engineer executes File -> Delete -> Multiproject in SIMATIC Manager expecting to purge the entire project suite, they frequently discover that while the multiproject container disappears, all subproject directories and libraries remain intact on the hard drive. This article explains the architectural principles underpinning STEP 7 multiprojects, details the modularity and asset-protection design philosophy, and provides verified procedures for safe subproject deletion and clean filesystem management.

Architecture and Fundamental Mechanics

STEP 7 Multiproject Directory Architecture and Modularity Design:

Container vs Subproject File Structure:
In SIMATIC Manager, a Multiproject is technically a top-level relationship catalog. On disk, the multiproject is represented by a folder containing an .s7m management file and catalog database tables.
The constituent subprojects (e.g. AS_Area1, AS_Area2, OS_Server) and Master Data Libraries (Master_Lib) are completely independent STEP 7 project directories, each with its own project file (.s7p or .s7l), block folders, CFC databases, and WinCC SQL project instances.
The Modularity and Data Protection Principle:
In large industrial plants, engineering is distributed across teams. Subprojects are frequently extracted from the multiproject (Multiproject -> Remove for Editing), transferred to external contractors, and later reintegrated (Multiproject -> Reapply after Editing).
Furthermore, standardized automation blocks and Master Data Libraries are commonly shared or migrated between different plant units using Multiproject -> Insert into Multiproject.
If deleting a multiproject automatically erased all underlying subprojects and libraries, a single accidental click could permanently destroy hundreds of hours of engineering work across multiple controllers. Therefore, SIMATIC Manager restricts multiproject deletion strictly to the .s7m relational container, leaving all individual project assets untouched on disk.

Step-by-Step Implementation Procedure

Understand the Scope of Multiproject Deletion:
* Selecting File -> Delete -> Multiproject removes only the .s7m container database from SIMATIC Manager. The physical subproject folders on disk are intentionally preserved.
Delete Subprojects and Libraries Individually in SIMATIC Manager:
* If you want to permanently delete all engineering assets:
* Open SIMATIC Manager.
* Open the Multiproject (File -> Open -> Multiproject).
* In the Component View, expand the tree to view all subprojects and libraries.
* Select a subproject, right-click, and select Delete (or choose File -> Delete -> Project).
* A confirmation dialog appears asking to confirm deletion of the project and its files from disk. Confirm with Yes.
* Repeat this operation for each AS project, OS project, and the Master Data Library.
* Finally, execute File -> Delete -> Multiproject to delete the empty multiproject container.
Manual Filesystem Cleanup of Orphaned Subprojects:
* If the multiproject container was already deleted leaving orphaned project folders:
* Close SIMATIC Manager, CFC, and WinCC Explorer to ensure no file locks remain.
* Open Windows File Explorer and navigate to your project storage directory (e.g. D:\Siemens\Step7\S7Proj).
* Locate the folders corresponding to the orphaned subprojects (containing .s7p files) and libraries (.s7l files).
* Permanently delete the folders from Windows Explorer, or move them to an external archive volume.
Proper Archiving Best Practice:
* Before deleting any multiproject or subproject, always create a full compressed backup using File -> Archive -> Multiproject. This bundles the multiproject container and all linked subprojects into a single verifiable .zip archive.

Verification

Verify Complete Removal of Multiprojects and Subprojects:
1. In SIMATIC Manager, select File -> Open -> Multiproject. Confirm that the deleted multiproject name no longer appears in the list.
2. Select File -> Open -> Project. Confirm that the deleted subprojects no longer appear in the project list.
3. Open Windows File Explorer and navigate to the project directory; confirm that subproject directories are completely removed and drive space is recovered.

Limitations and Operational Precautions

Operational Precautions and File Locking Constraints:
- Never delete subproject directories from Windows File Explorer while SIMATIC Manager, CFC, or WinCC Explorer is running; locked database files will cause partial deletions and corrupted registry pointers.
- Master Data Libraries often contain shared plant-wide model types, SFC types, and custom block libraries. Never delete a Master Data Library without confirming that no other active multiproject references it.
- If an OS project is deleted via Windows Explorer instead of SIMATIC Manager, the local SQL Server database instances (CC_...) may remain attached to the SQL Server service, requiring manual detachment.

Engineer FAQ

Why did subprojects remain after I deleted the multiproject?

SIMATIC Manager deletes only the overarching .s7m multiproject management database. Subprojects and libraries are preserved on disk by design to prevent accidental data destruction and support modular reuse.

How do I delete subprojects along with their files on disk?

In SIMATIC Manager, delete each subproject individually using File -> Delete -> Project. Confirming the dialog deletes the project from both SIMATIC Manager and the Windows filesystem.

Can I re-use a subproject after its multiproject has been deleted?

Yes. In SIMATIC Manager, open any other multiproject, right-click, and select 'Multiproject -> Insert into Multiproject'. Browse to the preserved subproject folder to link it to the new multiproject.

What file extension designates a STEP 7 Multiproject?

A Multiproject is identified by the .s7m file extension, whereas standard projects use .s7p and libraries use .s7l.

How can I extract a single subproject for external contractor engineering?

Right-click the subproject in SIMATIC Manager and select 'Multiproject -> Remove for Editing'. Once contractor work is complete, use 'Multiproject -> Reapply after Editing' to restore cross-project links.