Recovering Disappeared CFC Charts and Resolving 'HARDWARE_ERROR: INVALID_DRIVE' in SIMATIC PCS 7

In SIMATIC PCS 7, the catastrophic condition where all CFC charts suddenly disappear from the project tree accompanied by error logs displaying 'HARDWARE_ERROR Hardware error: INVALID_DRIVE', 'RMS_DRIVE_AVAIL = SYSTEM_ERROR', and 'ES_REGISTER_APP = SYSTEM_ERROR' occurs when the host Windows operating system hard drive partition is converted from a standard 'Basic Disk' to a Windows 'Dynamic Disk'. The Step 7 engineering environment, its embedded database engine (Sybase/C-ISAM), and the Record Management System (RMS) require direct physical partition geometry and low-level block addressing provided only by Basic Disks. When a disk is converted to Dynamic, Step 7 fails to resolve drive volume handles, rendering all chart folders empty. Converting the drive back from Dynamic Disk to Basic Disk (using non-destructive partition tools) immediately restores all CFC charts and project data without data loss.

Architecture of the Step 7 Record Management System (RMS) and CFC Database

The Continuous Function Chart (CFC) editor in SIMATIC PCS 7 is not a simple drawing tool; it is a complex relational engineering database system. Chart files (.cfc), block interconnections, parameters, and run sequences are managed by the Record Management System (RMS) and the Table Management System (TMS).

The RMS server initializes during SIMATIC Manager startup, creating memory-mapped swap files, buffer lists, and virtual memory pools directly tied to the physical drive geometry and file system volume descriptors of the host workstation.

Root Cause Analysis: Why Dynamic Disks Break SIMATIC PCS 7

Windows Disk Management allows users to alter hard drive configurations, frequently prompting users to convert disks from 'Basic' to 'Dynamic' when creating new volumes or expanding partitions. For standard office applications, Dynamic Disks function transparently. However, for industrial control software, it introduces fatal incompatibilities:

Volume Abstraction Incompatibility: Dynamic Disks utilize the Logical Disk Manager (LDM) database at the end of the physical disk, abstracting disk sectors into software volumes. Legacy industrial software components—including Step 7 RMS and S7DOS—rely on standard Master Boot Record (MBR) partition tables.
Handle Resolution Failure: When the RMS server queries the operating system for drive geometry via low-level kernel APIs (RMS_DRIVE_NUMBER), the Dynamic Disk driver returns an unrecognized volume type, triggering HARDWARE_ERROR: INVALID_DRIVE.
Apparent Data Loss: Because RMS cannot initialize swap files on the drive, SIMATIC Manager suppresses the entire CFC chart hierarchy, giving the terrifying appearance that all engineering work has been wiped out.

Decoding the Error Log: INVALID_DRIVE and RMS Initialization Failures

The error log generated in the CFC/SFC diagnostic directory details the exact cascade of failures:

0xEE03000F RMS_DRIVE_NUMBER = HARDWARE_ERROR Hardware error: INVALID_DRIVE: The core RMS engine cannot validate the physical partition type.
RMS_DRIVE_AVAIL and RMS_DRIVE_READY: The drive availability checks fail, passing the error up the software stack.
RMS_SWAP_FILE_INIT and RMS_BUFFER_LIST_INIT: The system fails to allocate the temporary swap files required to hold open CFC chart structures.
TMS_SERVER_INIT and ES_REGISTER_APP: The Table Management Server and Engineering System application registration abort, closing the CFC interface.

Step-by-Step Recovery Procedure: Converting Dynamic Disk Back to Basic Disk

To recover the disappeared CFC charts without losing project data, the disk must be reverted to a Basic Disk:

Do NOT Reinstall PCS 7: Reinstalling PCS 7 or applying CFC updates will not fix the issue, as the underlying disk partition remains dynamic.
Do NOT Use Windows Disk Management Delete: Windows Disk Management only permits converting a dynamic disk to basic if you FIRST delete all volumes on the disk, which would destroy all data!
Utilize a Non-Destructive Partition Utility: Use a proven disk management utility (such as Acronis Disk Director, EaseUS Partition Master, or AOMEI Dynamic Disk Converter) that supports in-place conversion from Dynamic to Basic disk.
Execute In-Place Conversion: Select the affected system drive, choose Convert to Basic Disk, and apply changes. The utility rewrites the standard MBR/GPT partition tables without modifying stored data files.
Restart Computer: Allow Windows to reboot and re-enumerate the physical basic disk partitions.
Launch SIMATIC Manager: Open the PCS 7 Multiproject. Open the AS station; all CFC charts, hierarchy folders, and block interconnections will reappear completely intact.

Comparison of Windows Basic Disks vs Dynamic Disks in Automation Environments

The following table compares Basic Disks and Dynamic Disks regarding compatibility with industrial automation software:

| Storage Attribute | Windows Basic Disk | Windows Dynamic Disk |
|---|---|---|---|
| Partition Structure | Standard MBR or GPT Partition Tables | Logical Disk Manager (LDM) Proprietary Database |
| SIMATIC PCS 7 / Step 7 Compatibility | 100% Certified and Mandated | Completely Unsupported (Causes RMS Crashes) |
| WinCC SQL Server Compatibility | Fully Supported | High risk of SQL cluster and segment detachment |
| Dual-Boot and Disaster Recovery | Standard disk cloning tools work seamlessly | Cloning and sector-level imaging frequently fail |
| Recommended Status | Mandatory for all ES, OS, and BATCH Stations | Strictly Prohibited across all PCS 7 Nodes |

Verification

Verify complete recovery of the PCS 7 project:
1. Open Windows Disk Management (diskmgmt.msc); verify that all hard drives display disk type Basic with healthy NTFS partitions.
2. Launch SIMATIC Manager; navigate through the Plant Hierarchy and Component View of the AS station.
3. Confirm that all CFC charts appear with their original names, timestamps, and icons.
4. Open a complex CFC chart; verify that block layouts, interconnections, and parameter values render without errors.
5. Execute a CFC compilation check (Chart > Check > Consistency); confirm that the database integrity check reports zero errors.

Limitations and Operational Precautions

Never convert hard drives on industrial automation computers to Dynamic Disks. If disk partitioning modifications are required (e.g., resizing partition C: or D:), use dedicated partition resizing tools that maintain the Basic Disk format. Establish a strict routine of frequently archiving PCS 7 multiprojects to external media or network shares using SIMATIC Manager's built-in File > Archive... function to protect against hardware failures.

Engineer FAQ

Are my CFC charts really lost when this error occurs?

No! The actual database files (.cfc, .dbf, .s7p) remain completely unharmed on the hard drive. Step 7 simply cannot read them because the RMS database engine cannot initialize on a dynamic disk.

Why does Windows Disk Management ask to convert to Dynamic Disk?

When you attempt to create more than 4 primary partitions on an MBR disk, Windows defaults to converting the entire physical disk to Dynamic to bypass the 4-partition limit. To avoid this, create an Extended partition with Logical drives instead.

Does Microsoft SQL Server support Dynamic Disks?

While Microsoft SQL Server can run on dynamic disks, Microsoft officially discourages dynamic disks on production database servers due to performance degradation and complex disaster recovery.