Fixing LOGO! Soft Comfort V7 USB Driver on Windows 8

Problem Details

Engineers deploying Siemens LOGO! Soft Comfort V7 (LSC V7) on a fresh Windows 8 or Windows 8.1 workstation frequently report that the programming suite installs cleanly under Windows XP compatibility mode, but the LOGO! PC cable (USB) never enumerates as a usable virtual COM port. When the user opens Extras > Options > Interface in LOGO! Soft Comfort and tries to establish a connection to a LOGO! 0BA7 or 0BA8 base module, one of the following symptoms is observed:

• A pop-up warning: "Cannot install 32-bit version on a 64-bit system" (or the reverse) when Windows tries to attach the bundled CP210x driver to the USB device.
• The cable is detected in Device Manager under Other devices with a yellow bang and a Windows error such as Code 28 (drivers not installed) or Code 39 (cannot load driver).
• The LOGO! Soft Comfort > Interface dialog shows no COM port in the drop-down list, or the drop-down lists COM1 only.
• Clicking PC ↔ LOGO! transfer returns a timeout and the cable LED does not flash red/green during negotiation.

Because the error wording is intentionally generic and Microsoft tightened driver-signing rules beginning with Windows 8 (released October 2012 and succeeded by Windows 8.1 in October 2013), the bundled VCP driver on the LSC V7 DVD no longer self-installs. The platform mismatch is the dominant root cause, not a hardware defect in the cable.

Affected Software, Hardware, and Operating Systems

Root Cause Analysis

The LOGO! PC cable does not contain a native USB-HID interface. It exposes a virtual COM port through a Silicon Labs CP210x USB-to-UART bridge controller. For the bridge to enumerate under Windows 8, the OS must load the matching CP210x VCP (Virtual COM Port) driver, signed with a Windows 8-compatible catalog file.

The CP210x VCP installer on the LOGO! Soft Comfort V7 DVD is dated for Windows 2000 / XP / Server 2003 / Vista. Although the installer is technically able to run on Windows 8, two things go wrong:

1. Driver-signature enforcement — Windows 8 enforces Secure Boot / Driver Signature Enforcement by default. The legacy CP210x INF on the LSC DVD carries an older cross-certificate that the Win8 driver store rejects when the device is first hot-plugged.
2. 32-bit / 64-bit driver-store separation — Windows 8 x64 requires a 64-bit kernel-mode driver. If the LSC installer was run from a 32-bit build of setup.exe, only the x86 driver tree is unpacked to %SystemRoot%\System32\DriverStore, and the x64 enumeration fails with the generic mismatch warning shown by Device Manager.

The fix is therefore not to disable driver signing, but to (a) install the legacy INF on the DVD so the device is recognised, and (b) immediately update the driver in Device Manager with a Win8-signed CP210x release pulled down from the Silicon Labs driver distribution or the Windows Update catalog.

Prerequisites

• Local administrator rights on the Windows 8 / 8.1 host.
• LOGO! Soft Comfort V7 DVD (or an extracted install folder).
• LOGO! PC cable (Siemens 6ED1057-1AA01-0BA0).
• Optional but recommended: a current CP210x VCP driver package (version 6.7 or later) downloaded to C:\Drivers\CP210x\.
• An available USB 2.0 port (USB 3.0 ports on Windows 8 also work once the driver is signed; see Microsoft KB 2808271 history for Win8 USB 3.0 stack improvements).
• LOGO! 0BA7 or 0BA8 base module powered with 12/24 V DC or 115/230 V AC, with the cursor on the display at the main screen (otherwise the device rejects the upload request).

Solution: Step-by-Step Procedure

1. Install LOGO! Soft Comfort V7 in Windows XP compatibility mode.
   Right-click setup.exe on the LSC DVD → Properties → Compatibility → tick Run this program in compatibility mode for: Windows XP (Service Pack 3) → also tick Run as administrator. Choose the correct build (32-bit or 64-bit) that matches the host OS architecture. Complete the install. Do not connect the USB cable yet.
2. Browse the LSC DVD for the CP210x driver.
   On the LSC V7 DVD the driver is typically located at Drivers\USB_Cable\CP210x_VCP_Win2K_XP_S2K3_Vista.exe. Copy the file to C:\Temp\. Do not run it yet.
3. Pre-stage the driver files with the legacy installer.
   Right-click CP210x_VCP_Win2K_XP_S2K3_Vista.exe → Run as administrator. Accept the licence. The installer copies the INF, SYS, and CAT files to %SystemRoot%\System32\DriverStore\FileRepository\silabser\.... This step is required because Windows 8 needs a candidate driver before the device is plugged in.
4. Plug in the LOGO! PC cable.
   Insert the cable into a USB 2.0 port. Windows 8 will enumerate the device, attempt to install the legacy driver, and may report "Device driver software was not successfully installed" — this is expected.
5. Update the driver in Device Manager.
   Open Control Panel → Device Manager. The cable will appear as Other devices → CP210x USB to UART Bridge Controller with a yellow exclamation mark. Right-click → Update Driver Software → Browse my computer for driver software → Let me pick from a list of device drivers on my computer → Show All Devices → Have Disk → navigate to the CP210x VCP folder you downloaded in step 1. Pick Silicon Labs CP210x USB to UART Bridge (WDF) for Windows 8 / 8.1.
6. Confirm the new driver is active.
   After the wizard completes, the device moves from Other devices to Ports (COM & LPT), listed as Silicon Labs CP210x USB to UART Bridge (COMx). The most common assignment is COM5; numbers above COM9 are fine but require the matching port to be entered manually in LSC because the V7 interface dialog only lists COM1–COM9 by default.
7. Configure LOGO! Soft Comfort to use the new port.
   Start LSC V7 (still under XP compatibility, still as administrator) → Extras → Options → Interface. Choose PC-COM as the connection type and select the new COM port. Set baud rate to 9600 for 0BA7 modules and 115200 for 0BA8 modules (the higher rate is negotiated automatically once the cable is acknowledged).
8. Run a transfer test.
   From the LSC main menu choose PC ↔ LOGO! → LOGO! → PC (Upload). The cable LED should flash orange during the handshake, then turn steady green on success. The base module displays the running program ID at the top of its screen.

Verification

After the eight steps above, the following checks confirm the fix is stable across reboots:

1. Device Manager shows no error codes. The entry Silicon Labs CP210x USB to UART Bridge (COM5) has no warning icon. Right-click → Properties → General reports Device status: This device is working properly. The driver version should be 6.7.4.260 or newer; older builds occasionally return to Code 28 after a Windows quality update.
2. LOGO! Soft Comfort sees the port. Extras → Options → Interface → PC-COM lists the new COM port. Click Test; the dialog reports Interface test successful within 3 seconds.
3. End-to-end upload/download round-trip. A short ladder program (one NO contact, one output coil) uploads to the LOGO! and downloads back to LSC within 10 seconds. The checksum displayed in LSC matches the checksum in the LOGO! menu (Start → Program → Memory Card → Copy will not be used; only PC ↔ LOGO! is required).
4. Hot-plug resilience. Unplug the cable, wait 5 seconds, replug — Windows 8 re-enumerates the port on the same COM number (the COM5 assignment persists in the registry under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB\VID_10C4&PID_EA60\...).

Compatibility Mode Configuration

Although the CP210x driver fix is the primary action, the LOGO! Soft Comfort V7 application itself still benefits from the legacy compatibility shim on Windows 8 because several UI dialogs and the project archive writer predate Win32 changes in the long-path API.

• Open File Explorer → C:\Program Files (x86)\Siemens\LOGO! Soft Comfort V7\ (or the matching x64 path).
• Right-click LOGOComfort.exe → Properties → Compatibility.
• Set Run this program in compatibility mode for: Windows XP (Service Pack 3).
• Set Run this program as an administrator.
• Click Change settings for all users to apply the shim to the per-machine shortcut as well.

Common Error Messages and Fixes

Advanced Diagnostics

When the standard procedure does not bring the cable online, the following deeper checks help isolate the failure to driver, cable, or base module.

1. Driver-signature verification. Open an elevated command prompt and run signtool verify /v /c:c:\drivers\cp210x\silabser.inf. The signtool ships in the Windows 8 SDK. A pass confirms the INF is Win8-signed; a fail pinpoints the offending certificate.
2. USB descriptor inspection. Run USBTreeView or Microsoft USBView (part of the Win8 WDK). The LOGO! cable reports VID 0x10C4 and PID 0xEA60 for the CP2102/CP2103 variant, or PID 0xEA70 for the CP2102N variant. If a different VID/PID appears, the cable has been re-flashed (or is counterfeit) and a different driver family is required.
3. Serial-port smoke test with PuTTY. Open PuTTY in Serial mode at 9600 8-N-1 on the assigned COM port. Press the LOGO! cursor-up key on the base module; the cursor changes but no traffic is expected on the programming port. This confirms the COM port is live and the cable is wired correctly without involving LSC.
4. Kernel-mode trace. From an elevated command prompt, run logman start usbtrace -p Microsoft-Windows-USB-USBPORT -o usbtrace.etl -ets, reproduce the plug-in event, and stop with logman stop usbtrace -ets. Open the ETL in Netmon to see whether the OS sent the standard USB enumeration descriptors or stalled at the configuration request.
5. Power-supply check at the LOGO!. The CP210x cable draws its 5 V from the USB port and converts to 3.3 V for the UART side. A weak 24 V supply on the LOGO! (below 22 V at the terminals) can still allow the base module to boot but cause the UART handshake to fail. Measure at the LOGO! terminals with a true-RMS multimeter.

Field Commissioning Checklist

Before leaving a cabinet where the LOGO! PC cable is the only programming path, verify the following items:

• Device Manager reports the cable on a stable COM port (COM5 is the conventional choice).
• LOGO! Soft Comfort V7 runs without re-prompting for administrator elevation.
• An upload/download round-trip with a 1-rung test program completes in under 10 seconds.
• The LOGO! base module firmware is at the revision expected by the project (0BA7: ES7 or later for full V7 compatibility, 0BA8: FS4 or later for the high-speed upload).
• The CP210x VCP driver version is documented in the handover (right-click driver → Properties → Driver → Driver Version).
• The LSC V7 project is archived to the customer’s engineering repository; the on-board LOGO! memory card slot is left empty unless the application uses a battery-backed SRAM card.

Notes on Other Programming Paths

The USB cable is the most common path for ad-hoc programming, but on Windows 8 there are two alternatives that do not depend on the CP210x driver:

• Ethernet / PROFINET on 0BA8 modules (6ED1052-xxx08-0BA2 and later). LSC connects to IP 192.168.0.10 by default; the driver stack is the standard Win8 TCP/IP, no Silicon Labs involved.
• Ethernet on LOGO! CMR2020 / CMR2040 routers used as remote access gateways. LSC uses the LOGO! CMR WebUI to forward the LOGO! protocol across the cellular link, again without the CP210x driver.

If repeated driver updates on a fleet of Windows 8 tablets become a maintenance burden, migrating the engineering workstations to LOGO! 0BA8 + Ethernet programming is the long-term remediation: it eliminates the CP210x dependency entirely and survives future Windows 10/11 driver-deprecation cycles.

Frequently Asked Questions