Replacing Redundant WinCC OS Server Network Cards: Mixed Network Interface Cards and Simatic Shell Configuration

When replacing a failed Terminal Bus network adapter in a redundant SIMATIC PCS 7 WinCC OS Server pair, the replacement card does not need to match the model, chipset, or form factor of the partner server. You can install an add-in PCIe Ethernet adapter on the failed server while keeping the onboard network adapter on the partner server. The critical operational requirements are: configuring the new adapter with a valid IP address in the Terminal Bus subnet, ensuring the Redundancy connection remains on a completely separate subnet, selecting the correct adapter in Simatic Shell, and disabling the defective adapter in Windows Device Manager.

Hardware Asymmetry in Redundant WinCC OS Server Configurations

In high-availability SIMATIC PCS 7 systems, OS Server pairs run in hot standby redundancy. A common operational concern arises when a network interface card (NIC) fails on one of the servers: does the replacement NIC have to be identical in make, model, and slot location to the card installed on the healthy redundant partner?

The Siemens WinCC redundancy communication layer operates entirely at the network protocol layer (TCP/IP, Named Connections, and RPC). WinCC is hardware-agnostic regarding physical Ethernet adapters. A server utilizing a PCIe commercial gigabit network card (such as an Intel I210/I350) operates seamlessly alongside a partner server utilizing an onboard motherboard Realtek or Intel adapter, provided network layer parameters and bandwidth capabilities match.

Terminal Bus vs Redundancy Link Network Segmentation

A PCS 7 OS Server typically possesses three segregated network physical layers:

Plant Bus (System Bus): Dedicated communication to S7-400 CPUs (typically via CP 1623 / CP 1628 or Softnet Industrial Ethernet).
Terminal Bus: Communication between OS Servers, OS Clients, Engineering Stations, and Process Historian. This is where operator commands and client screen requests flow.
Redundancy Link: A private cross-connect (direct patch cable or dedicated switch) used exclusively by WinCC Redundancy for database synchronization and heartbeat health monitoring.

Crucial Rule: The Redundancy Link and Terminal Bus must reside in distinct IP subnets (e.g., Terminal Bus on 192.168.1.x/24 and Redundancy Link on 10.0.0.x/24). Never bridge or combine these subnets.

Configuring Simatic Shell for the New Network Interface Card

The most critical software step after installing a new network card is re-binding Simatic Shell:

Open Windows Explorer on the repaired server.
Navigate to This PC -> Simatic Shell.
Right-click Simatic Shell and select Settings....
In the adapter selection dropdown, select the newly installed network card dedicated to the Terminal Bus.
Ensure the Multicast Life Time and Port settings match the redundant partner server identically.
Click OK to re-initialize network sockets. WinCC will discover other stations across the Terminal Bus.

Handling Motherboard NIC Failures and Disabling Defective Hardware

If the failed adapter is an integrated onboard motherboard port:

An intermittent or flapping onboard NIC can flood the Windows network stack with link-state interrupts.
After inserting the new PCIe network card, open Windows Device Manager -> Network adapters.
Right-click the defective onboard network card and select Disable device (or disable the controller entirely in the PC BIOS/UEFI).
This prevents Windows from attempting to route packets across a damaged physical port.

Redundant Server Network Architecture and Interface Matrix

The following table summarizes network adapter roles and configuration guidelines across redundant OS servers:

Network LayerPhysical Interface OptionHardware Symmetry Required?Subnet AssignmentPrimary Communication RoleTerminal BusOnboard NIC or PCIe Add-in CardNo (Mixed models fully supported)Standard Corporate / Plant LAN SubnetClient-Server HMI traffic, alarms, faceplatesRedundancy LinkSecond Standard Ethernet NIC / CrossoverNo (Mixed models fully supported)Isolated Private Subnet (e.g. 10.0.0.x)WinCC Redundancy synchronization and heartbeatPlant Bus (System Bus)CP 1623, CP 1628, or BCE Standard NICRecommended matching for identical driversS7 Subnet / Industrial EthernetAS-OS S7 Named Connections to S7-400 CPUsSimatic Shell BindingMust bind to Terminal Bus NICIdentical subnet configuration on both nodesTerminal Bus IPStation discovery, remote project activation

Step-by-Step Procedure to Replace and Commission the Failed NIC

Follow this operational procedure to perform a live, hot-replacement without plant shutdown:

Confirm Redundancy Health: Ensure the partner OS Server is in active runtime (Master) and handling all OS Clients.
Deactivate Runtime: On the server with the broken NIC, safely close WinCC Runtime and shut down Windows.
Install Hardware: Insert the replacement PCI-Express Ethernet card into an available slot.
Boot and Install Drivers: Power up the machine, install vendor-certified Windows network drivers.
Configure IP and Disable Failed Port: Assign the original Terminal Bus IP address, subnet mask, default gateway, and DNS servers. Disable the broken port in Device Manager.
Bind Simatic Shell: Open Simatic Shell -> Settings. Re-bind to the new network adapter. Click OK.
Network Verification: Ping OS Clients and the partner OS Server across the Terminal Bus.
Start WinCC Runtime: Launch WinCC. The server will enter runtime as Standby and automatically initiate Redundancy Archive Synchronization from the Master server.

Verification

Confirm system health through these verification methods:

Simatic Shell Visibility: In Simatic Shell, expand the tree. Ensure all OS Clients and the partner OS Server appear blue/active.
Redundancy State Tag Audit: In WinCC Tag Management, monitor @RedundancyState. Verify Server A and Server B are healthy (1 = Master, 2 = Standby).
Archive Synchronization: Inspect the WinCC Alarm Logging list. Ensure message Redundancy archive synchronization started appears and finishes with Synchronization completed.
Failover Test: Perform an orderly failover test during a planned maintenance window to verify client transparency.

Limitations and Operational Precautions

Observe the following safeguards:

Duplex and Speed Settings: Set the network adapter speed/duplex to Auto-Negotiation or hardcode to 1 Gbps Full Duplex matching the managed switch port.
Windows Firewall Exceptions: Verify Windows Firewall allows all WinCC and PCS 7 rules on the new adapter connection profile (Domain/Private).
Commercial Accuracy Disclaimer: Software order numbers (MLFBs), package structures, and hardware capacity prerequisites vary across PCS 7 versions and hardware platforms. System integrators must confirm exact software entitlements and licensing requirements against the official Siemens Catalog CA 01 and obtain an authorized Siemens distributor quotation prior to purchasing.

Engineer FAQ

Do I need to replace network cards in pairs across both servers?

No. Purchasing and installing a second card for the healthy partner server is completely unnecessary unless you want hardware symmetry for spare parts standardization.

Will replacing the network card trigger a license violation in Automation License Manager?

No. Standard WinCC runtime and redundancy licenses are not node-locked to network card MAC addresses.

What happens if Simatic Shell is not bound to the new card?

If Simatic Shell is left unbound or pointing to a disconnected adapter, the server will fail to communicate with OS Clients and cannot synchronize historical archives with its partner.