Resolving PC Adapter USB V2.0 Driver Install on Windows 7 x64

Problem Details

The Siemens SIMATIC PC Adapter USB family is the standard MPI/PROFIBUS-to-USB bridge used to program S7-200, S7-300, S7-400, C7, and ET 200 stations from a Windows engineering workstation. Two catalog variants dominate installed bases today: the legacy PC Adapter USB V2.0 (Siemens order number 6ES7 972-0CB20-0XA0) and the current PC Adapter USB A2 (6GK1571-0BA00-0AA0). When the CD-based installer is launched on a Windows 7 Professional or Enterprise x64 SP1 engineering station with STEP 7 V5.5 SP3 / SP4, the wizard aborts before copying any file and reports:

Setup interrupted. The wizard was interrupted before PC Adapter USB could be completely installed. Your system has not been modified. To complete installation at another time, please run Setup again.

After the failed setup, plugging the adapter into any USB 2.0 or 3.0 port triggers Windows Device Manager to enumerate it under "Other devices" or as a yellow-banged "SIMATIC PC Adapter USB" with one of the following device manager error codes:

STEP 7 V5.5 (Options → Set PG/PC Interface) does not list "PC Adapter (USB)" in the Interface Parameter Assignment Used dropdown, and TIA Portal V13 SP1 (Project → Online → Accessible Nodes) returns "No online connection could be established". The adapter is detected by the USB hub layer but cannot bind to the S7MPI / S7PROFIBUS protocol stack.

Affected Hardware Identification

Before any driver remediation, physically verify the order number printed on the adapter label and in Device Manager. The part-number determines which driver path is valid and whether the unit is supported at all on a 64-bit OS with TIA Portal:

Root Cause Analysis

The CD bundled with the PC Adapter USB V2.0 ships a driver package dated for Windows XP and Windows 7 32-bit. The installer performs a platform check at the very beginning; on a 64-bit kernel it executes an early-exit branch and returns "Setup interrupted" without writing any .sys, .inf, or .cat file. The hardware enumeration then defaults to Microsoft's generic usbccgp.sys, which knows nothing about the S7MPI framing on top of the FTDI bulk endpoint, so Device Manager surfaces a yellow bang and DeviceInstanceId remains under the root hub.

The three layered root causes observed in the field are:

1. Installer gating — the 32-bit-only setup.exe aborts before any registration. No driver store entry is created.
2. Driver signature enforcement — Windows 7 x64 enforces SE_DRIVER_SIGNATURE_REQUIRED (Code 52). The 1.0.0.0 driver shipped on the CD is WHQL-signed only for x86.
3. FTDI VCP vs D2XX confusion — the adapter is not a Virtual COM Port. Installing the FTDI VCP driver causes the device to bind to comport.sys and ignores the S7 protocol shim, which results in Code 28 and no PC Adapter entry in PG/PC Interface.

Software Compatibility Matrix

Solution A — Update Driver via Siemens Support Entry 109476315

This is the manufacturer-supported procedure for Windows 7 64-bit systems that already have STEP 7 V5.5 or TIA Portal installed but cannot establish an online connection to the PLC. The official entry is at the Siemens Industry Online Support portal:

Siemens Entry ID 109476315 — Update driver software for the PC Adapter USB

Prerequisites:

• Local administrator rights on the Windows 7 x64 workstation
• STEP 7 V5.5 SP3 / SP4 already installed (the driver path is relative to %ProgramFiles(x86)%\Siemens\Automation\S7WIN)
• TIA Portal V13 SP1 or later if TIA is the engineering tool
• USB 2.0 port directly on the workstation (avoid unpowered hubs during first install)

Procedure:

1. Close STEP 7, TIA Portal, and the S7DOS Help service.
2. Open Control Panel → Device Manager.
3. Plug the PC Adapter USB into a USB 2.0 port. The device should appear under Other devices with a yellow exclamation mark.
4. Right-click → Update Driver Software → Browse my computer for driver software.
5. Click Let me pick from a list of device drivers on my computer.
6. Select Show All Devices → Have Disk → Browse.
7. Navigate to C:\Program Files (x86)\Siemens\Automation\S7WIN\DRIVERS\usb (or the equivalent on the TIA DVD Support\DRIVERS\PC_Adapter_USB).
8. Select SiemensUsbDriver.inf and confirm.
9. Approve the Windows Security prompt for the Siemens AG driver signature.
10. Wait for "Windows has successfully updated your driver software".
11. Unplug, wait 5 seconds, and replug the adapter to confirm clean enumeration.

Solution B — Manual Driver Installation from Windows Update Catalog

If the STEP 7 DVD is unavailable or corrupt, retrieve the 64-bit signed driver from a working engineering station and apply it manually. This is the workaround that has been field-proven on isolated engineering PCs without STEP 7 installed.

1. On a second Win 7 x64 machine with STEP 7 working, copy the folder %ProgramFiles(x86)%\Siemens\Automation\S7WIN\DRIVERS\usb\x64 to a USB stick.
2. On the affected machine, open Device Manager, locate the yellow-banged SIMATIC PC Adapter USB, and choose Update Driver.
3. Browse to the USB stick path and select s7usb64.inf.
4. When Windows warns that the driver is unsigned, choose Install this driver software anyway (the signature is present; the warning text is the standard Win 7 driver-install phrasing).
5. Reboot and verify in Device Manager that the device shows Driver Provider: Siemens AG and Driver Version: 1.0.0.0 (or newer per Siemens package).

Solution C — Disable Driver Signature Enforcement (Last Resort)

Only use this method if the signed driver install still rejects with Code 52 and you have validated the driver package is genuine Siemens material. Disabling signature enforcement lowers the workstation's security posture and is not recommended for production environments.

1. Open Start → All Programs → Accessories, hold Shift and right-click Command Prompt, choose Run as different user → Administrator.
2. Execute: bcdedit /set nointegritychecks ON
3. Reboot. The "Disable driver signature enforcement" option appears under Advanced Boot Options (press F8 during POST).
4. Boot into that mode, then run Solution A or B above.
5. Re-enable enforcement after verification: bcdedit /set nointegritychecks OFF

STEP 7 V5.5 PG/PC Interface Configuration

After the driver is installed, configure STEP 7 to bind to the USB interface:

1. Open SIMATIC Manager.
2. From the menu choose Options → Set PG/PC Interface.
3. In the Interface Parameter Assignment Used dropdown, select PC Adapter (USB).
4. Click Properties and confirm:
   • USB port: the enumerated COM-equivalent or USB\VID_0908&PID_0001\...
   • Transmission rate: 187.5 kbps for default MPI on S7-300/S7-400
   • Highest station address (HSA): 31 for MPI, 126 for PROFIBUS
   • PC is the only master on bus: leave unchecked if PG is shared with HMI panel
5. Click OK and then OK on the parent dialog.
6. Open PLC → Accessible Nodes. STEP 7 should enumerate the CPU within 5 seconds.

TIA Portal V13 SP1 Online Configuration

1. Open the TIA Portal project.
2. Select the project view, expand the project tree to Devices & networks.
3. In the Network view, click the PC station's PG/PC interface.
4. In the Inspector pane under Properties → Interface assignments, choose PC Adapter USB A2.
5. Set PROFIBUS address 0, transmission rate 1.5 Mbps (or 187.5 kbps for MPI on legacy S7-300).
6. Click Go online → Accessible nodes. TIA should discover the CPU within 10 seconds.

Hardware Verification Procedure

After driver install and PG/PC binding, run this end-to-end verification matrix:

Troubleshooting Matrix

USB Subsystem Diagnostics on Windows 7

If the adapter still fails after the Siemens driver is applied, isolate the USB stack itself. Microsoft publishes a structured diagnostic flow for "USB ports not working" that applies to device enumeration problems generally and is useful when Device Manager never even lists the adapter under any category:

Microsoft Q&A — USB Ports Not Working

Field-proven checks before swapping cables or PCs:

• Run msinfo32 → Components → USB and confirm the host controller is reported as enabled, no error status, and no "Device failed enumeration" entries.
• Open devmgmt.msc → View → Devices by connection to confirm the adapter sits behind the correct USB hub tier. Devices behind more than two tiers often fail with insufficient power.
• Disable USB selective suspend: Power Options → Change plan settings → Change advanced power settings → USB settings → USB selective suspend setting → Disabled.
• Check BIOS/UEFI for Legacy USB Support or XHCI Hand-off. Some HP and Dell workstations default to auto, which can disrupt isochronous endpoints used by FTDI bulk transfers.
• Run sfc /scannow to confirm usbhub.sys, usbport.sys, and usbehci.sys are intact.

Non-Siemens Clone Adapter Caveats

The discussion thread surfaced multiple non-Siemens PC Adapter USB clones, often labeled "SIMATIC PC Adapter USB V2.0 compatible" but built on CH340 or FTDI FT232R bridges with cloned EEPROM signatures. Engineering stations with TIA Portal V13 SP1 or STEP 7 V5.6 and later may detect these clones but reject them during S7MPI handshake because the EEPROM does not carry the Siemens vendor ID (VID 0x0908 / PID 0x0001 for V2.0; VID 0x0908 / PID 0x0005 for A2).

Field-Proven Caveats

• Do not unplug the adapter during an active download — the S7MPI state machine can leave the CPU in STOP with SF LED lit, requiring a power cycle to recover.
• USB 3.0 ports on older xHCI controllers (Renesas uPD720202, Etron EJ168) intermittently drop the FTDI bulk endpoint under heavy disk I/O. Use a rear-panel USB 2.0 port for the adapter.
• STEP 7 V5.5 SP3 prior to HF7 carries a known bug where the USB driver path is incorrectly written to %ProgramFiles%\Siemens\Automation\S7WIN instead of the x86 program files folder. Apply HF7 or higher before relying on Solution A above.
• On virtual machines (Hyper-V, VMware Workstation, VirtualBox), USB passthrough must be enabled at the VM level and the host controller must support USB 2.0 in the VM configuration. Some VMware versions present the adapter as a low-speed device, which the Siemens driver rejects.
• After Windows updates KB3033929 or KB3125574 (Convenience rollup), re-verify the driver binding. Microsoft has been known to swap s7usb64.sys with the generic usbser.sys during driver ranking.

Standards Reference

• EN 50170 / IEC 61158 — PROFIBUS physical layer and timing parameters used by the adapter at 9.6 kbps to 12 Mbps.
• Siemens SIMATIC PC Adapter USB A2 manual, order number 6GK1 571-0BA00-0AA0, release 03/2015.
• Siemens Entry 109476315 — driver update procedure (linked above).

FAQ