Replacing a Failed Redundant OS Server in SIMATIC PCS 7 - License Recovery and Redundancy Synchronization

Replacing a failed redundant OS Server in SIMATIC PCS 7 requires preparing a replacement PC with identical hardware/OS specifications, recovering software licenses via Automation License Manager (ALM) or Siemens Technical Support certificate re-licensing, performing an Entire OS Download from the Engineering Station (ES), and allowing WinCC Redundancy to execute automatic background archive synchronization across the Terminal Bus to restore historical data without interrupting live process control.

Redundant OS Server Failure and Recovery Architecture

In SIMATIC PCS 7 high-availability configurations, redundant OS Servers (Server A and Server B) operate in parallel. If Server A suffers catastrophic hardware failure (e.g. motherboard blowout or unrecoverable disk crash):
* Partner Continuity: Server B assumes sole mastership without interruption, maintaining plant bus communications and logging process archives.
* Replacement Strategy: A replacement industrial PC identical in terms of operating system, network interfaces, and PCS 7 release must be commissioned to restore redundancy before a second failure occurs.

Software License Recovery via ALM and Certificate of License (CoL)

Software licenses are node-locked to hardware identifiers. Handling licenses depends on the physical condition of the failed machine:
1. Bootable Hard Drive: If the old PC can boot (or the hard drive can be mounted via USB dock), open Automation License Manager (ALM) and transfer all license keys to a USB transfer drive.
2. Total Hardware Destruction: If the drive is unreadable, locate the original paper Certificate of License (CoL) documents provided in the product packaging. Contact Siemens Technical Support with scanned copies of the CoL and license numbers; Siemens Customer Support will issue emergency replacement authorization keys to restore licensed operation.

Hardware Commissioning and Terminal Bus Configuration

To integrate the replacement PC into the PCS 7 architecture, ensure all parameters precisely mirror the required network and operating system settings:

Parameter / LayerFailed / Target Server SettingsOperational Partner ServerEngineering RuleOperating SystemWindows Server 2012 R2 Standard (or matching release)Windows Server 2012 R2 StandardOS build and service pack must match exactly.Computer Namee.g. OS_SRV_Be.g. OS_SRV_AMust match the NetBIOS name defined in SIMATIC Manager.IP Address (Terminal Bus)Static IP (e.g. 192.168.1.12)Static IP (e.g. 192.168.1.11)Subnet mask and gateway must be identical.Network Adapter BindingTerminal Bus placed at top priorityTerminal Bus placed at top priorityConfigured via Windows Advanced Network Settings.Security ControlRun 'Repeat Settings' in SIMATIC Security ControlConfigured during initial commissioningEstablishes identical DCOM and firewall rules.Automation License ManagerTransfer PCS 7 OS Server + Redundancy licensesValid active server licenses installedBoth servers must have identical PO and redundancy entitlements.

Entire OS Download and Automated Redundancy Resynchronization

The following workflow restores the server to active operation:

[Engineering Station (ES) -> SIMATIC Manager]
   │
   ├─► Open Multiproject -> Component View
   ├─► Select OS Server Object -> Right-click Server Data -> Generate
   │
   ├─► Right-click the Replacement OS Server Object -> PLC -> Download
   │     • Scope: Select (•) "Entire project"
   │     • Target Path: Select remote destination path across Terminal Bus
   └─► Download transfers the WinCC project and creates the local SQL database
         │
         ▼
[Launch WinCC Runtime on Replacement Server]
   │  • Open WinCC Explorer on the replacement machine -> Activate Runtime
   │  • WinCC Redundancy detects partner server runtime active on the Terminal Bus
   │  • Background Synchronization: Surviving server transmits missing alarm and tag
   │    archives to the replacement server until both databases are 100% synchronized!

Procurement Notice: Validate all final license quantities, media packages, and part numbers against current Siemens Industry Mall catalogs and with an authorized Siemens distributor quotation prior to procurement.

Verification

To confirm that the replacement OS Server is fully restored and synchronized:
1. In WinCC Explorer on both servers, verify that the Title Bar displays active runtime status without demo warnings.
2. Launch the WinCC redundancy diagnostic tool channel_diag.exe or open the internal tag @RedundancyState; verify that both servers show status OK.
3. In WinCC Alarm Logging, verify that historical alarms missing during the outage have been back-filled and match the partner server.
4. Verify that OS Clients communicate seamlessly across both servers without connection dropouts.
5. In SIMATIC Shell, verify that both servers display blue computer icons under the Terminal Bus tree.

Limitations and Operational Precautions

Never deactivate the surviving operational OS Server while commissioning the replacement server. The surviving server must remain in continuous runtime to provide process control and to serve as the master data source during archive synchronization. Ensure the Terminal Bus has sufficient bandwidth (1 Gbps recommended) during redundancy synchronization to prevent network congestion.

Engineer FAQ

How long does WinCC Redundancy take to synchronize missing data?

Synchronization duration depends on the outage length and archive volume. A 24-hour outage typically synchronizes within 15 to 30 minutes over a Gigabit Terminal Bus.

What happens if I don't have the original Certificate of License (CoL)?

Without the paper CoL or proof of purchase, Siemens cannot legally re-issue lost software licenses, requiring the procurement of replacement license packages. Always store CoLs in a secure plant archive.

Do I need to download to OS Clients after replacing an OS Server?

If the computer name, IP address, and server data packages remained identical, OS Clients do not require re-downloading; they detect the recovered server automatically.

Can I use a newer hardware model PC as a replacement server?

Yes, provided the newer industrial PC is officially released for your specific PCS 7 version and the operating system and network card drivers are fully compatible.