Virtualizing SIMATIC PCS 7 V8.1 - VMware Workstation vs VMware vSphere ESXi

Virtualizing SIMATIC PCS 7 V8.1 using VMware Workstation (such as Workstation 14) is technically possible but strictly restricted to offline testing, software simulation, and temporary engineering. VMware Workstation is a Type-2 hosted hypervisor running on top of a desktop Windows OS, lacking the deterministic latency, hardware high availability, and network isolation required for production automation. For productive plant operations (redundant OS Servers, OS Clients, BATCH, and Route Control), Siemens exclusively certifies and releases bare-metal Type-1 hypervisors—specifically VMware vSphere ESXi V5.5 and V6.0 for PCS 7 V8.1 SP1.

Hypervisor Architecture: Type-1 (vSphere ESXi) vs Type-2 (Workstation)

Understanding the architectural distinction between hypervisor tiers is fundamental when designing DCS infrastructure:

Type-2 Hypervisors (VMware Workstation / Player): The virtualization software runs as an application inside a standard desktop operating system (e.g., Windows 10). Host OS background tasks, antivirus scans, and Windows update restarts interfere with the guest VM, introducing unpredictable multi-second execution delays.
Type-1 Hypervisors (VMware vSphere ESXi): The virtualization layer acts as a bare-metal micro-kernel operating system installed directly on enterprise server hardware. Virtual machines communicate directly with physical processors and network controllers, ensuring microsecond-level deterministic scheduling.

Certification Boundaries for PCS 7 Virtualization

The table below details Siemens certification boundaries across virtualization platforms:

Virtualization PlatformHypervisor ArchitectureApproved PCS 7 V8.1 RolesProduction Plant Operation StatusVMware Workstation 12 / 14Type-2 (Hosted on Windows Desktop)Offline Engineering Station (ES), Demo, Software TestingNot Released: Prohibited for productive plant runtime.VMware vSphere ESXi V5.5Type-1 (Bare-Metal Enterprise)ES, Redundant OS Server, OS Client, BATCH, PHFully Certified & Released for PCS 7 V8.1 SP1.VMware vSphere ESXi V6.0Type-1 (Bare-Metal Enterprise)ES, Redundant OS Server, OS Client, BATCH, PHFully Certified & Released for PCS 7 V8.1 SP1 / V8.2.Microsoft Hyper-VType-1 (Windows Server Role)Limited OS Client / Web Navigator rolesRestricted: Specific PCS 7 version approvals apply.

Hardware Requirements for Production Virtualization

When virtualizing PCS 7 V8.1 on certified VMware ESXi hosts, implement these mandatory design standards:

Dedicated Physical Network Adapters: Segregate the Plant Bus (Industrial Ethernet connection to controllers) and Terminal Bus (server-to-client communication) onto separate physical NICs and virtual switches (vSwitch).
Zero Memory Overcommit: Configure 100% RAM reservation for all OS Server and Process Historian virtual machines to prevent disk paging during process alarm floods.
CP 1623 Direct Mapping: Utilize VMDirectPath I/O (PCI passthrough) to assign physical CP 1623 cards directly to virtual OS Servers if hardware-offloaded ISO communication is required.
NTP Time Synchronization: Disable VMware Tools guest-to-host time synchronization; synchronize all virtual machines via NTP from a physical external master clock (e.g., SICLOCK TC 400).

Verification

To verify virtualized environment compliance:

If running VMware Workstation for engineering: verify that simulation tools (S7-PLCSIM, WinCC Runtime) execute without license warnings.
On production ESXi hosts: verify in vSphere Client that hypervisor build indicates ESXi 5.5 or 6.0.
In VM Options, confirm that 'Synchronize guest time with host' is Unchecked.
Launch SIMATIC Assessment Suite - Data Collector (SAS-DC) inside the virtual machine: confirm virtualization tests report zero compatibility warnings.
Verify that WinCC OS redundancy synchronizes across redundant virtual servers hosted on separate physical ESXi hosts.

Limitations and Operational Precautions

Operational boundaries when virtualizing PCS 7:

Redundant Server Separation: Never place both redundant OS servers (Server 1 and Server 2) on the same physical ESXi hypervisor server; host hardware failure would result in total control room blackout.
No Support for Physical I/O on Workstation: VMware Workstation cannot properly manage PCI/PCIe passthrough for CP 1623 communication processors.
Licensing Compliance: Virtualizing PCS 7 components requires identical Siemens software runtime licenses as physical machines.

Engineer FAQ

Can I use VMware Workstation to test a PCS 7 project on my engineering laptop?

Yes. VMware Workstation is widely used and approved for offline project engineering, functional testing, and simulation with S7-PLCSIM.

Why is VMware Workstation forbidden in actual plant operations?

Workstation runs on top of a desktop host OS. If the host OS crashes, installs updates, or experiences high CPU load, the DCS virtual machine freezes, risking loss of operator visibility and plant trips.

Which VMware vSphere version is certified for PCS 7 V8.1 SP1?

VMware vSphere ESXi V5.5 and V6.0 are officially certified and released for PCS 7 V8.1 SP1.

Why must VMware Tools time synchronization be disabled in PCS 7 VMs?

VMware Tools forces periodic step adjustments that can move virtual clock time backwards, corrupting WinCC SQL archive tables and alarm sequence-of-events logging.