Virtualizing PCS 7 OS Servers: VMware ESXi PCIe Passthrough vs SOFTNET-IE S7-REDCONNECT
To virtualize a SIMATIC PCS 7 OS Server that communicates with redundant S7-400H controllers over fault-tolerant S7 connections, engineers cannot use desktop virtualization (such as VMware Workstation/Player), because desktop hypervisors cannot pass physical PCIe hardware into virtual machines. Instead, engineers must choose between two approved architectures: deploying enterprise VMware vSphere / ESXi with DirectPath I/O (PCIe Passthrough) to bind the physical CP 1623 card directly to the guest VM, or adopting the Siemens-recommended virtual architecture utilizing standard virtual network adapters (VMXNET3) paired with the SIMATIC NET SOFTNET-IE S7-REDCONNECT software package. The SOFTNET-IE approach eliminates physical hardware card dependencies, enabling full VMware vMotion, automated failover, and hardware-independent backups.
Table of Contents
- The Challenge of Specialized Communications Hardware in Virtual Environments
- Why Desktop Virtualization (VMware Workstation) Fails with CP 1623
- Architecture 1: VMware vSphere / ESXi DirectPath I/O (PCIe Passthrough)
- Architecture 2: Standard Virtual NICs with SOFTNET-IE S7-REDCONNECT (Recommended)
- Virtualization Strategy and Feature Comparison Matrix
- Verification
- Limitations and Operational Precautions
- Engineer FAQ
- Technical References
- Related Articles
- Related Tags
The Challenge of Specialized Communications Hardware in Virtual Environments
In physical SIMATIC PCS 7 installations, OS Servers connecting to redundant S7-400H controllers frequently utilize dedicated communication processors:
* SIMATIC CP 1623 (Order No. 6GK1162-3AA00): A PCIe card featuring an integrated microprocessor running onboard communication firmware.
* SIMATIC NET Hardnet-IE S7-REDCONNECT: Offloads S7 fault-tolerant protocol handling from the PC's CPU onto the CP 1623.
When migrating OS Servers into virtualized data centers (such as VMware vSphere), traditional hardware assumptions fail. Virtual machines interact with virtualized hardware abstractions, creating configuration challenges when attempting to mount proprietary industrial PCIe cards inside guest operating systems.
Why Desktop Virtualization (VMware Workstation) Fails with CP 1623
Engineers attempting to test virtualized OS servers on desktop hypervisors (VMware Workstation or VMware Player) encounter fatal roadblocks:
- Lack of Direct Hardware Access: Desktop hypervisors bridge network traffic through virtual software switches that emulate standard Intel or Realtek NICs.
- Station Configuration Editor Rejection: Inside the guest Windows VM, the SIMATIC Station Configuration Editor inspects the physical hardware bus. Because the hypervisor does not expose the raw PCIe registers of the CP 1623, the card is not detected.
- S7-REDCONNECT Incompatibility: Attempting to insert an 'IE General' card in Station Configurator will not support S7-REDCONNECT without the dedicated software package.
- Conclusion: Desktop virtualization products cannot be used for production PCS 7 OS Servers requiring CP 1623 communication.
Architecture 1: VMware vSphere / ESXi DirectPath I/O (PCIe Passthrough)
In enterprise deployments where physical CP 1623 cards must be retained:
- Bare-Metal Hypervisor: Install VMware ESXi directly onto server hardware (e.g., Siemens SIMATIC IPC or enterprise HP/Dell rack servers).
- Enable DirectPath I/O:
* Open the VMware vSphere Client.
* Navigate to Host -> Manage -> Hardware -> PCI Devices.
* Locate the Siemens CP 1623 Communications Processor and enable Pass-through.
* Restart the ESXi host. - Assign to Virtual Machine:
* Edit VM Settings for the PCS 7 OS Server.
* Add a PCI Device -> select the CP 1623 card. - Guest OS Operation:
* Power on the VM. Windows detects the physical CP 1623 natively.
* Install standard Siemens Hardnet drivers and configure the Station Configuration Editor.
Architecture 2: Standard Virtual NICs with SOFTNET-IE S7-REDCONNECT (Recommended)
While PCIe passthrough functions technically, it binds the virtual machine to a specific physical server chassis, disabling core virtualization benefits (such as VMware vMotion, High Availability HA, and automated disaster recovery).
Siemens officially recommends migrating to SIMATIC NET SOFTNET-IE S7-REDCONNECT (Order No. 6GK1704-0HB00-0AA0):
1. Virtual Hardware: Configure two standard virtual network adapters (VMXNET3) inside the VM, mapped to separate physical network uplinks for Plant Bus redundancy.
2. Software Stack: Install SOFTNET-IE S7-REDCONNECT on the guest OS. The communication stack handles S7-H redundancy entirely in software.
3. Station Configurator: The network cards are inserted as IE General adapters, fully supporting fault-tolerant connections in NetPro.
4. Key Advantage: The VM is completely decoupled from specialized hardware, allowing seamless migration across ESXi cluster nodes during host hardware maintenance.
Virtualization Strategy and Feature Comparison Matrix
The following table compares the two primary virtualization approaches for PCS 7 OS Servers:
6GK1162-3AA00)6GK1704-0HB00-0AA0)Adopting SOFTNET-IE S7-REDCONNECT modernizes plant infrastructure while providing full high-availability virtualization.
Verification
To verify that the virtualized OS Server communicates reliably with the S7-400H:
1. In the guest OS Station Configuration Editor, verify that the communication adapters indicate state 'RUN' without component warnings.
2. Open NetPro and download the S7 fault-tolerant connection to the virtual PC station.
3. Activate WinCC Runtime on the virtualized OS Server.
4. Open WinCC Channel Diagnosis; confirm that the S7-H Named Connection indicates 'Ready / OK'.
5. Physically disconnect one of the redundant plant bus cables on the ESXi host; confirm that WinCC continues updating tags without interruption.
Limitations and Operational Precautions
- Never deploy production virtualized OS Servers on unapproved desktop hypervisors like VMware Workstation or VirtualBox.
- When using PCIe passthrough, ESXi memory reservations must be set to 100% of guest RAM, locking host memory pools.
- Ensure physical switch ports connected to ESXi uplinks are configured with appropriate VLAN tags and Spanning Tree PortFast.
- Always validate final license quantities, virtualization packages, and MLFBs against the applicable Siemens catalog and authorized distributor quotation.
Engineer FAQ
Can VMware vMotion move an active WinCC OS Server without dropping PLC connections?
Yes. When using SOFTNET-IE S7-REDCONNECT and enterprise ESXi with dedicated vMotion networks, live migration between physical hosts occurs within milliseconds without dropping S7-H connections.
Why does Station Configuration Editor reject CP 1623 inside VMware Workstation?
VMware Workstation does not support direct hardware register mapping for PCI devices. It emulates generic virtual NICs that do not present the Siemens hardware subsystem IDs required by the CP 1623 driver.
What is the maximum number of AS connections supported by SOFTNET-IE S7-REDCONNECT?
SOFTNET-IE S7-REDCONNECT supports up to 64 S7 fault-tolerant connections, which is more than sufficient for standard PCS 7 OS Server architectures.
Technical References
- SIMATIC Process Control System PCS 7 Virtualization Manual (Entry 51975791)
- Siemens Industry Online Support Entry 63098071: SIMATIC NET SOFTNET-IE S7-REDCONNECT Product Information
- VMware vSphere DirectPath I/O Deployment Guide
Related Articles
- How to Troubleshoot S7-H Communication Alarms Between Automation Stations and WinCC OS
- Configuring Terminal Bus and Plant Bus Network Adapters in SIMATIC PCS 7
- Essential PCS 7 Engineering: S7-H NetPro Connections, PLCSIM Testing, and Analog Scaling
Related Tags
- Virtualization
- CP 1623
- VMware ESXi
- SOFTNET S7-REDCONNECT
- PCIe Passthrough