Resolving HW Config Freezes on WinCC Application Insertion and Unmanaged Switch Limitations in PCS 7

In SIMATIC PCS 7 V9.1, HW Config hanging or reporting 'Not Responding' when attempting to save and compile a SIMATIC PC Station containing a WinCC Application is caused by Microsoft SQL Server database creation deadlocks or missing Windows security group memberships. When saving a PC station with WinCC Application, HW Config calls CCProjectServer.exe to initialize the WinCC database. If the user account lacks membership in 'SIMATIC HMI' and 'SIMATIC NET', or if SQL Server (WINCC) encounters file permissions or NTFS compression errors, the API call freezes indefinitely. Regarding unmanaged switches like the SCALANCE XB005 (6GK5005-0BA00-1AB2): unmanaged switches lack IP addresses and PROFINET/SNMP diagnostic engines, meaning they do not exist in the HW Config catalog and cannot be configured in STEP 7. Furthermore, unmanaged switches are strictly prohibited for redundant Plant Bus networks (S7-400H / CP 443-1), which mandate managed switches (SCALANCE X-200 / X-300) supporting MRP, RSTP, or standby redundancy.

Executive Summary

Configuring PC Stations and industrial network topologies in SIMATIC PCS 7 requires adherence to strict operating system permissions and network device classifications. Control engineers frequently encounter two distinct hurdles during system configuration: first, HW Config freezing when compiling a newly inserted WinCC Appl in a PC Station; second, confusion regarding why economical unmanaged Industrial Ethernet switches—such as the SCALANCE XB005—cannot be found in the hardware catalog to connect redundant S7-400H controllers. Resolving the HW Config freeze requires verifying SQL Server service status and local user group privileges, while proper network design mandates utilizing managed switches to support fault-tolerant DCS communication.

Architecture and Fundamental Mechanics

The interaction between STEP 7 HW Config, the WinCC database server, and network hardware operates across distinct architectural layers:

The HW Config WinCC Scaffolding Call:
* When an engineer inserts a WinCC Application into a PC Station and clicks Save and Compile, HW Config does not merely write hardware system data blocks (SDBs).
* It executes an inter-process DCOM handshake with the WinCC project server (CCProjectServer.exe and s7wzwd.exe) to scaffold the corresponding WinCC project database (*.mdf / *.ldf).
* This routine issues SQL commands to the local instance MSSQL$WINCC.
* If the logged-on Windows account is not registered in the local groups SIMATIC HMI and SIMATIC NET, or if SQL Server 2017 cannot create transaction logs due to NTFS permission blocks, the thread enters an infinite kernel wait state. The Windows desktop flags HW Config as 'Not Responding'.
Unmanaged vs. Managed Switches in PCS 7 (SCALANCE XB005):
* Unmanaged Switches (e.g., SCALANCE XB005 / 6GK5005-0BA00-1AB2): Operate strictly as transparent Layer 2 multiport repeaters/bridges. They have no microprocessor running an IP stack, no MAC table management configuration, and zero PROFINET IO device capabilities. Because there are no parameters to assign (no IP, no subnet, no diagnostic alarms), unmanaged switches never exist in the HW Config catalog.
* Managed Switches (e.g., SCALANCE X-200, X-300): Contain active management firmware with PROFINET device integration, SNMP diagnostics, and ring redundancy protocols (MRP, HRP, RSTP).
Why Unmanaged Switches Cannot Be Used for Redundant Plant Bus:
* Redundant S7-400H systems connected to dual OS Servers via S7-REDCONNECT or CP 443-1/443-5 require deterministic, loop-free network topologies.
* If redundant cables are connected between controllers and unmanaged switches, a catastrophic network broadcast storm occurs instantly because unmanaged switches cannot manage ring protocols (MRP) or block redundant ports. Communication collapses within seconds.

Step-by-Step Implementation Procedure

Follow these procedures to resolve the HW Config freeze and implement compliant network switching:

Resolve the HW Config 'Not Responding' Freeze:
* Terminate the frozen HW Config task via Windows Task Manager (Ctrl + Shift + Esc).
* Verify user group memberships: Press Win + R, type lusrmgr.msc, and press Enter.
* Ensure your Windows user account is a member of:
- SIMATIC HMI
- SIMATIC NET
- Administrators
- Verify SQL Server service: Open services.msc, locate SQL Server (WINCC), and verify status is Running.
- Check project folder permissions: Ensure the project directory is not compressed (NTFS compression disabled) and grants 'Full Control' to the SIMATIC HMI group.
- Log off Windows and log back in to refresh the security token.
- Reopen SIMATIC Manager, insert the WinCC Appl in the PC Station, and click Save and Compile.
Proper Deployment of the SCALANCE XB005:
* Understand that the SCALANCE XB005 cannot and does not need to be added to HW Config or NetPro.
* If used, it is purely a physical unmanaged bridge. It is suitable only for non-redundant, non-critical terminal bus links (e.g., connecting a local office printer or non-redundant maintenance laptop).
Selecting Managed Switches for Redundant Systems:
* For redundant AS 414-5H / CP 443-1 and redundant PC Stations, replace unmanaged switches with managed switches:
- SCALANCE XC208 (6GK5208-0BA00-2AC2) or SCALANCE X204-2 (6GK5204-2BB10-2AA3).
- In HW Config, insert the managed SCALANCE X switch from PROFINET IO > Network Components > SCALANCE X.
- Assign IP addresses, configure Media Redundancy Protocol (MRP) ring roles (Redundancy Manager vs. Client), and connect to the AS and OS stations.
Final Compilation and Verification:
* Compile HW Config and NetPro without errors.
* Download configuration to the PC Station via Station Configuration Editor.

Verification

After verifying user groups, open the PC Station in HW Config, insert the WinCC Application, and click 'Save and Compile'. Confirm that compilation finishes in under 10 seconds without freezing. Open WinCC Explorer directly from SIMATIC Manager; confirm that the OS database opens smoothly. For the network, verify that managed SCALANCE switches indicate green fault-tolerant ring status.

Limitations and Operational Precautions

Never install unmanaged switches inside an industrial ring topology. Plugging both ends of a cable into an unmanaged switch or connecting two unmanaged switches across redundant links will cause an immediate network freeze. Always consult authorized Siemens catalog data when specifying industrial network hardware.

Engineer FAQ

Why is SCALANCE XB005 missing from the HW Config catalog?

The XB005 is an unmanaged switch with no IP stack or PROFINET interface; only managed devices with configurable diagnostic parameters exist in HW Config.

Can I create a standalone WinCC project if HW Config freezes?

Yes. If HW Config freezes, test creating a project directly in WinCC Explorer. If WinCC Explorer also fails, the issue is confirmed to be SQL Server or user group permissions.

Can SCALANCE XB005 be used for the Terminal Bus?

It can be used physically for simple, non-redundant client connections, but managed switches (SCALANCE XC-200) are strongly recommended for industrial diagnostics and security.