Resolving Siemens and Allen-Bradley Software Conflicts on One PC

Overview: Why Siemens and Allen-Bradley Coexistence Is Hard

Engineering workstations rarely run a single vendor's toolchain. A controls engineer supporting a brownfield plant may need Siemens STEP 7 or TIA Portal to maintain SIMATIC S7-300, S7-400, or ET 200 CPUs while simultaneously commissioning Allen-Bradley ControlLogix or CompactLogix controllers with Studio 5000 Logix Designer and RSLinx Classic. Installing both stacks on bare-metal Windows is technically possible but exposes the engineer to a series of well-documented driver, service, COM-port, and registry conflicts that range from nuisance to project-blocking. The PIC (PICOM) bridge driver that STEP 7 V5.5 registers for its "PC Internal" MPI/PROFIBUS interface routinely collides with the RSLinx Classic DF1 driver, and the Allen-Bradley virtual backplane hijacks the COM ports that the Siemens Automation License Manager enumerates.

This reference documents the three deployment patterns that field engineers use to make the two stacks coexist reliably: bare-metal dual-boot, virtualization with VMware Workstation or Hyper-V, and a hybrid that keeps one stack on the host OS and the other inside a VM. It expands each option with specific catalog numbers, driver service names, registry keys, and verification steps so the engineer can build a workstation that survives re-installs, customer audits, and rolling upgrades. For vendor-side documentation, refer to the Siemens SiePortal and the Rockwell Automation Support portals.

Software Stack Compatibility Matrix

The matrix below captures the supported Windows generations for the most widely deployed engineering tool versions. Use this to decide whether a given pair of stacks can coexist on a single bare-metal image or whether one of them must live inside a VM. Where the source data is ambiguous about exact update levels, treat the entry as the highest generally available patch at the time of publication and verify against the manufacturer's release notes before commissioning.

Driver and Service Conflicts on a Single Host

When the two stacks are installed side-by-side on a bare-metal Windows 10 or 11 image, the engineer will hit a predictable list of service, kernel-driver, and registry conflicts. The most common are documented below together with the mitigation.

PIC / S7DOS Helper Service

STEP 7 V5.5 and earlier install the PICOM user-mode service (registered as s7oiehsx or s7oiehsx64) which brokers I/O to the Siemens "PC Internal" MPI/PROFIBUS interface. The same registry hive is updated by the Siemens Automation License Manager service. When the RSLinx Classic DF1 driver enumerates COM ports, it reads HKLM\HARDWARE\DEVICEMAP\SERIALCOMM and may pick up Siemens-created COM ports (COM3-COM10 are commonly repurposed). Disabling the S7DOS Helper is possible but breaks STEP 7's online functions. The supported workaround is to move STEP 7 into a VM and isolate the COM enumeration entirely. The helper is restarted on demand by the STEP 7 diagnostic tools but will not survive a Windows Defender scheduled scan.

DF1 Driver and RSLinx Virtual Backplane

RSLinx Classic installs its own DF1 driver (AB_ETH-1.DLL, RSLDF1.DLL) and registers a virtual backplane. The driver maintains persistent state in HKLM\SOFTWARE\Rockwell Software\RSLinx\DF1 and creates hidden COM port handles for DF1 packet assembly. When the user uninstalls or rolls back a RSLinx version, the COM handles orphan and reappear as COM3 / COM4 even after the cable is unplugged. A re-install of the matching RSLinx build is the only clean fix. The same registry hive also records the ABCIP driver used for EtherNet/IP; deleting its keys without uninstalling RSLinx leaves the system in an inconsistent state that prevents subsequent installs from completing.

RSLinx OEM vs. Lite vs. Professional

The three RSLinx Classic SKUs - OEM, Lite, and Professional - have distinct driver surfaces. Mixing them on the same image frequently produces a "drive not loaded" state for either DF1 or EtherNet/IP. The engineer must commit to a single RSLinx SKU per host OS and uninstall any prior SKU via Control Panel before installing the new one. FactoryTalk Activation Manager should also be re-licensed to match the active RSLinx edition; otherwise Studio 5000 will fail to enumerate drivers at first run.

WinCC Flexible and TIA Portal HMI Migration

Two WinCC Flexible installations on one workstation (for example SP2 and SP5) will share the "RT Archive" directory in %ProgramFiles%\Siemens\WinCCFlexible\WinCC Flexible 2008\RT and overwrite each other's startup entries. Only one SP level may be installed at a time. Migrating a project from WinCC Flexible 2008 to TIA Portal WinCC must be done in a clean, single-version image; otherwise panel images fail to compile with cryptic WinCC error 13002 "unknown tag container".

USB Driver Stack Collisions

Both vendors ship kernel-mode drivers for their USB adapters (Siemens s7usb64.sys for the PC Adapter, Rockwell ab_usbnet.sys for the 1784-U2DHP family). When both are installed, Windows enumerates them under different USB class GUIDs but the Device Manager tree occasionally merges their child devices into a single HID group. Disabling one or the other under Device Manager > View > Devices by connection reveals the offending hierarchy and forces the engineer to re-plug the cable.

Hardware Prerequisites for a Dual-Stack Workstation

Whether the engineer chooses dual-boot or virtualization, the workstation must meet or exceed the following envelope. Cutting these numbers results in TIA Portal compile times that exceed one hour or Studio 5000 routines that hit the 30-minute ladder rebuild threshold.

Virtualization Architecture Options

Three hypervisor families are field-proven for dual-vendor PLC programming.

VMware Workstation Pro

VMware Workstation Pro 17.x is the most widely deployed option for engineering teams. It supports USB passthrough with full USB 3.1 device-class compatibility, isolated virtual networks (VMnet2 / VMnet3), serial port mapping to physical COM ports, and snapshot-based rollbacks before installing firmware updates. The host OS retains full WinCC and TIA Portal runs while one VM hosts the entire Allen-Bradley stack with RSLinx Classic and Studio 5000. USB licensing dongles (Siemens CP 5711 and Allen-Bradley 1784-PCIC clones) attach directly to the VM via the removable devices menu. Refer to the official VMware Workstation Pro documentation for the USB compatibility matrix.

Microsoft Hyper-V

Hyper-V is included with Windows 10/11 Pro and Server 2019+. It supports nested virtualization, Enhanced Session Mode for clipboard and drive sharing, and external virtual switches for physical NIC isolation. Limitations include no direct USB device passthrough (only USB redirection through Enhanced Session, which is incompatible with industrial USB adapters that require low-level interrupt endpoints), and no virtual serial port mapping to a physical COM port. Hyper-V is therefore recommended when the engineer uses Ethernet-only attachment (PROFINET over TCP/IP and EtherNet/IP) and can avoid USB MPI/PROFIBUS cables. Configuration details are documented in the Microsoft Hyper-V on Windows documentation.

Oracle VM VirtualBox

VirtualBox 7.x is free but requires the closed-source Extension Pack for USB 2.0/3.0 support. It handles USB 1.1 transparent to the guest, which is sufficient for legacy MPI PC Adapter but not for CP 5711 firmware uploads. Useful for budget-constrained test cells where the engineer only needs serial DF1 attachment. Note that VirtualBox's USB filtering does not honor USB device classes the way VMware does, and intermittent disconnects under heavy I/O are common.

Bare-Metal Dual-Boot Strategy

When virtualization overhead is unacceptable - for example, when an engineer is uploading firmware to multiple Siemens CP 5711 adapters in parallel using a high-speed USB 3.0 hub - bare-metal dual-boot is the most reliable path.

1. Provision a single workstation with two SSDs, each containing an independent Windows 10/11 installation. Windows Boot Manager handles the boot selection.
2. Install only the Siemens stack on SSD-1. Keep TIA Portal, WinCC, PLCSIM Advanced, and SIMATIC Automation Tool all in one image so the S7DOS Helper service runs unimpeded.
3. Install only the Allen-Bradley stack on SSD-2: Studio 5000 Logix Designer, RSLinx Classic (single SKU), RSNetWorx for ControlNet/DeviceNet, FactoryTalk View Studio, ControlFLASH.
4. Maintain a shared data partition (NTFS) where project archives and ACD/L5X files are stored. Both operating systems map the partition under the same drive letter and use the same file names. Avoid ReFS on the shared partition because some older Allen-Bradley tools refuse to write to it.
5. Schedule firmware updates only from the OS that owns the corresponding vendor toolchain; never cross-upgrade a 1756-EN2T module using ControlFLASH inside the Siemens image.

USB and Serial Port Passthrough Configuration

Industrial adapters depend on low-level USB endpoints that standard VM redirection cannot always expose. The configuration matrix below matches adapter to hypervisor.

VMware Workstation USB Passthrough

With the target VM powered off, open VM > Settings > USB Controller. Set USB compatibility to USB 3.1, enable "Show all USB input devices," and check "Automatically connect new USB devices." Power the VM on, then from the VM menu choose Removable Devices and connect the desired adapter. Verify in Device Manager (Windows guest) that the device appears without a yellow bang. If the device disconnects during heavy USB traffic, raise the "USB polling interval" preference under Edit > Preferences > USB.

Hyper-V Enhanced Session USB

Enhanced Session Mode (enabled in Hyper-V Settings under Enhanced Session Mode Policy) allows the user to attach USB devices via the menu bar after connecting to the VM. Industrial adapters that depend on interrupt-in packets (Siemens CP 5711 firmware update is the canonical example) will not function under Enhanced Session because the host intercepts the interrupt endpoint. The engineer must then use VT-d PCIe passthrough if the hardware supports it, or move to VMware. Hyper-V also cannot present a virtual COM port to a guest; for serial DF1 attachment use a USB-to-serial adapter with Enhanced Session USB redirection.

Network Isolation and Routing

PROFINET, EtherNet/IP, S7 communication, Modbus TCP, and OPC UA all ride on TCP/IP. The default NAT virtual switch on VMware or Hyper-V hides the guest from the host's broadcast domain, which is desirable for safety but breaks CIP routing through the host. The engineer should plan at least three virtual networks.

1. VMnet0 (Bridged) - the guest joins the plant network directly. Use this for EtherNet/IP and PROFINET discovery.
2. VMnet1 (Host-only) - isolated subnet for Studio 5000 and TIA Portal back to the host's RSLinx or Automation License Manager. Use 192.168.99.0/24 with the host at 192.168.99.1 and the guest at 192.168.99.2.
3. VMnet3 (Internal) - virtual network shared only between two guest VMs, useful when one VM hosts the Siemens stack and the other hosts Allen-Bradley but they must exchange live tags via OPC UA.

Set the Windows firewall on the host to block TCP port 44818 (EtherNet/IP CIP messaging) and TCP port 102 (ISO-on-TCP / S7) inbound when not actively commissioning. Both stacks will otherwise scan the broadcast domain and confuse the CIP scanner inside Studio 5000. Disable Windows network discovery on the host NIC dedicated to VMnet1 to prevent the host from broadcasting NetBIOS advertisements that interfere with PROFINET device names.

Licensing and Dongle Handling

Siemens relies on the Automation License Manager (ALM) service. ALM can host both local licenses and a floating license pool served from another workstation. For VMs, install ALM inside the same guest as the Siemens software and assign a unique ALM signature bound to the VM's MAC address. Snapshotting a VMware VM that holds an ALM lease can leave the license in a "borrowed" state until the engineer manually returns it from ALM.

Allen-Bradley transitioned from FlexNet to Flexera Activation in Studio 5000 v33 and forward. Activate via the RSA hard-lock USB key or, since v35, via the soft-activation file (CSF) bound to the workstation's TPM 2.0 chip. Within a VM, the engineer must clone the TPM provision or maintain a single VM UUID per activation. Mixing snapshot branches will silently invalidate the activation and the Studio 5000 splash screen will report "Activation has been invalidated" on every subsequent launch.

Step-by-Step VM Provisioning Procedure

The following procedure produces a hardened dual-stack workstation using VMware Workstation Pro 17.5 and Windows 11 Pro 23H2 as the host. Engineers targeting Hyper-V or VirtualBox adapt the steps to the equivalent menu items in those products.

Prerequisites

• VMware Workstation Pro 17.5 license key.
• Windows 11 Pro 23H2 installation ISO with TPM 2.0 enabled in UEFI.
• Windows 10 22H2 installation ISO for the guest VM (Studio 5000 v35 compatibility).
• Siemens TIA Portal V18 installation media (DVD or Siemens Software Center download).
• Allen-Bradley Studio 5000 v35 + RSLinx Classic 5.0 Professional installation package.
• Two USB ports reserved, one for CP 5711 and one for 1784-U2DHP.
• An Intel NIC on the host (avoid Realtek for VMware bridged networking at scale).

Procedure

1. Install Windows 11 Pro on the host. Enable virtualization (VT-x, VT-d) in UEFI. Confirm the "Hyper-V" hypervisor checkbox is OFF in Windows Features to avoid conflict with VMware.
2. Install the host-side Siemens stack: TIA Portal V18, WinCC V7.5 SP2, SIMATIC Automation Tool. Patch to the latest update level. Disable Windows Defender real-time scanning for the TIA Portal project directory to avoid compile-time stalls.
3. Install VMware Workstation Pro 17.5 and assign it one physical USB root. Reserve the other for the host's CP 5711.
4. Create a Generation-2-equivalent VM with 8 vCPUs, 24 GB RAM, 200 GB dynamic VMDK, 1 virtual NIC bridged, 1 virtual NIC host-only. Mount the Windows 10 ISO and install. Enable vTPM 2.0 in VM settings > Hardware > Security.
5. Inside the guest, install the Allen-Bradley stack in this exact order: RSLinx Classic 5.0 Professional, FactoryTalk Activation Manager, Studio 5000 Logix Designer v35, RSNetWorx for ControlNet, RSNetWorx for DeviceNet, FactoryTalk View Studio. Reboot after each major product.
6. Reboot. From VMware's Removable Devices menu, attach the 1784-U2DHP and confirm it appears in Device Manager inside the guest without error code 10 or 43.
7. In RSLinx Classic, configure the DF1 driver to point at the COM port that the 1784-U2DHP enumerates. Test via RSWho against a known PLC on the plant network.
8. Install ControlFLASH inside the guest and flash a 1756-EN2T to confirm USB passthrough is healthy. A successful firmware update proves the USB pipe is not being filtered by the hypervisor.
9. Configure a host-side scheduled task that launches the VM at login with elevated priority (VMware Workstation supports vmrun start scripts).
10. Validate end-to-end: from the host's TIA Portal, open Online > Accessible nodes and confirm the guest's PLC is reachable via the bridged NIC; from the guest's Studio 5000, run RSWho and confirm a Siemens PROFINET device responds via the OPC UA bridge or gateway.

Verification, Troubleshooting, and Field Tips

Before declaring the dual-stack workstation production-ready, run through the following checks. Each item maps to a concrete value the engineer can verify in the field.

Troubleshooting Matrix

Operational Tips from the Field

• Keep two USB keyboards - one for the host (TIA Portal), one for the guest (Studio 5000) - so that a frozen VM does not lock the engineer out of the host.
• Document the RSLinx build number on the workstation label. Mixing 5.0 and 4.4 silently breaks the DF1 driver.
• Patch Siemens first, Allen-Bradley second. A Siemens Service Pack that updates S7DOS Helper resets COM port enumeration for the entire system.
• Avoid binding to Wi-Fi for EtherNet/IP traffic. The broadcast storms during CIP routing overwhelm 802.11 retransmission timers.
• When a customer requests "the same software they have on their site", snapshot the workstation with that software set, then label the snapshot - not the entire VM - with the customer name.
• Schedule a weekly reboot of the VM. Long-running RSLinx sessions leak TCP sockets and eventually exhaust the non-paged pool on the host.
• Place the shared project archive on a NTFS ReFS-disabled volume; Studio 5000 v30+ refuses to save ACD files to ReFS.

Cross-Vendor Integration and Tag Mapping

Once the two stacks are stable on the workstation, the engineer will frequently face integration work that demands live tag exchange between a Siemens CPU and an Allen-Bradley Logix controller. Three pragmatic patterns cover most field scenarios.

Industrial Gateways

Dedicated protocol-translation gateways are the lowest-risk path. Common options include:

• Prosoft ICX35-HWC - EtherNet/IP to PROFINET IO Device translator.
• Anybus X-gateway (HMS Networks) - modular, supports EtherNet/IP Scanner and PROFINET IO Controller in one chassis.
• Phoenix Contact FL EP PN/PC - Ethernet-PROFINET/Ethernet-IP gateway.
• SICK SIG200 - sensor-level gateway for EtherNet/IP and PROFINET.

Configure the gateway from the Siemens workstation via TIA Portal (PROFINET side) and from the Allen-Bradley VM via Studio 5000 (EtherNet/IP side). The two configuration sessions do not interact because the gateway presents itself as a generic IO Device to TIA Portal and a generic scanner to Logix. Engineering effort is dominated by the GSDML / EDS file import; once imported, tag mapping is done in the gateway configuration tool, not in either PLC programming environment.

OPC UA Broker

When the plant already runs an OPC UA broker (Siemens WinCC Unified, Ignition, or KEPware), the engineer can publish S7 tags from TIA Portal to the broker and subscribe from Studio 5000 via the OPC UA AOI. Latency is typically 200-500 ms but the engineering effort is low. The OPC UA broker also decouples the two PLCs in time: a brief network outage on the EtherNet/IP side does not stall the PROFINET scan.

Direct CIP-to-S7 Routing

Some plants use a Siemens IE/PB Link or a Rockwell 1756-EN2T module with custom message instructions to route CIP reads/writes into S7 data blocks via TCP port 102. The MSG instruction in Logix can be configured with the S7 communication protocol, but the implementation is brittle and vendor support is limited. Reserve this pattern for non-critical monitoring or for one-time data migrations where a gateway is overkill.

Tag Naming Discipline

Regardless of the integration pattern, enforce a single tag-naming convention across both vendors. Use uppercase ASCII tags, separator = underscore, no spaces. TIA Portal and Studio 5000 both reject tags with hyphens or non-ASCII characters in some compiler passes. Import/export via CSV keeps both sides synchronized and provides a clean audit trail for functional safety reviews. Re-export the CSV after every routine change; the broker will silently drop tags that are renamed in only one PLC.