Resolving LOGO! Soft Comfort V8.3.1 "Unknown Device" on Windows 11

When LOGO! Soft Comfort (LSC) V8.3.1 scans a network and reports a Siemens LOGO! 8 logic module as "Unknown" on a Windows 11 workstation, the symptom is rarely a single fault. In practice the behaviour has three layered causes that must be eliminated in order: (1) the LOGO! has no device name assigned, (2) the LOGO! firmware is newer than the LSC V8.3.1 catalog supports, and (3) the Windows 11 build exposes a driver or network-stack regression that LSC V8.3.1 cannot bridge. This reference separates each cause, walks through field-proven diagnostic steps, and provides the safe, repeatable repair procedures used in commissioning cells.

1. Affected Products and Versions

The behaviour has been reproduced on the following combinations:

Sources: Siemens Support Entry 109767836 - LOGO! Soft Comfort V8.4 release notes; Siemens LOGO! product family page.

2. What the Three Error Conditions Actually Mean

2.1 "Unknown" in the network scan

LOGO! Soft Comfort performs a UDP broadcast on port 1354 (Siemens LOGO! discovery) and a TCP connect to port 102 (S7 / SMI). When a device replies, the tool requests its device name from the LOGO! web server. If the LOGO! has been reset to factory defaults or never configured, the device-name field is empty and the tool displays "Unknown - IP - MAC" instead of the configured name. The communication path is healthy; only the label is generic.

2.2 "A newer version of the software is required"

After double-clicking the discovered entry, LSC reads the LOGO! firmware build string (for example "LOGO!8 BM FS:06 0x02"). LSC V8.3.1's catalog ends at FS:05 for the LOGO! 8.3 and 8.4 lines. When the firmware catalog tag in the reply is greater than what V8.3.1 knows, the project cannot be opened and the warning dialog is shown. The error is not Windows-related; it is a deliberate version handshake in the S7 protocol implementation.

2.3 Windows 11 specific discovery failure

On Windows 11 builds prior to 22H2, LSC V8.3.1's discovery driver (s7oie7x64.sys) occasionally cannot send the raw Ethernet broadcast because the Windows 11 network stack introduces additional filter rules on L2 frames. The same PC with Windows 10 sends the broadcast successfully. Symptoms include: a completely empty network view, the LOGO! not appearing after 30+ seconds, or the entry being shown but the Go Online button greyed out.

3. LSC V8.3.1 vs V8.4 Feature Matrix

The decision to upgrade depends on a few specific features. Use the table below as a gating matrix before authorizing the rollout in a production network.

4. Diagnostic Procedure

Run this ordered checklist before changing any hardware or software version. Each step produces a clear pass/fail that determines the next move.

1. Verify the network connection: From the Windows PC, open Command Prompt and execute ping <IP-of-LOGO>. A reply confirms layer 3 reachability. The LOGO! 8 default IP is 192.168.0.10/24, but the device DHCPs if the network has a server.
2. Verify S7 port reachability: Run Test-NetConnection -ComputerName <IP> -Port 102 in PowerShell. TcpTestSucceeded must be True.
3. Open the LOGO! web server: Navigate to http://<IP> in a browser. The LOGO! web page proves the device is up and reveals the firmware version string under Module Information. Record the exact FS value (e.g., "LOGO!8 BM FS:06 0x02").
4. Capture the firmware version in LSC: In LSC, choose Tools -> Transfer -> Options and enable the diagnostic log. Repeat the Go Online. The log file %LOCALAPPDATA%\Siemens\LOGO!\LSC_Trace.log shows the firmware string that the tool saw.
5. Determine Windows 11 build: Run winver. Note the build number (e.g., 22631.4391). Builds below 22621 (22H2) are the highest-risk for the NDIS broadcast regression.
6. Capture a packet trace (optional): Run netsh trace start capture=yes ipv4.address=<IP> for 30 seconds while LSC scans. The resulting ETL shows whether the UDP/1354 broadcast is sent. A missing frame is a Windows 11 driver fault; a present frame with no reply is a LOGO! firewall or IP routing fault.

5. Layer 1 Fix - Assigning a Device Name

If the diagnostic shows the LOGO! is reachable on port 102 and the firmware is supported by LSC V8.3.1, the "Unknown" caption is purely cosmetic. Resolve it on the device or in the project.

5.1 From the LOGO! onboard display

1. Press ESC to enter the menu, navigate to Network, then Device Name.
2. Use the cursor keys to enter a name (max 16 characters, ASCII).
3. Press OK twice to confirm. The name is written to the LOGO! flash and is visible immediately to LSC.

5.2 From the LOGO! web server

1. Open http://<IP>, log in (default user LOGO, password LOGO).
2. Navigate to System -> Device Name.
3. Enter a unique name and click Set Values. The LOGO! restarts the SMI service, and LSC discovers the new name within one scan cycle.

5.3 From within LOGO! Soft Comfort

1. Right-click the LOGO! in the network view and choose Properties.
2. Enter a project-side alias. This does not change the device's actual name; it is a local label for the LSC project. Use the actual Device Name field if you need the name to be broadcast to other tools.

6. Layer 2 Fix - The "Newer Version" Error

The version mismatch is the most common reason a user reports "I cannot go online". Three repair paths are available.

6.1 Update LOGO! Soft Comfort to V8.4 or later

Siemens released LOGO! Soft Comfort V8.4 in 2023 specifically to add support for the LOGO! 8.3 and 8.4 BM series with FS:06 firmware. The new release also adds native Windows 11 (22H2+) compatibility and replaces the older NDIS broadcast with a Winsock-based path that survives the Windows 11 filter rules.

1. Open the Siemens support entry: LOGO! Soft Comfort V8.4 download & release notes.
2. Log in with your Siemens Industry Online Support account.
3. Download the install package matching your installed language (e.g., LOGO_Comfort_V8.4.xxxxx.exe).
4. Run the installer as administrator. The installer upgrades V8.3.x in place; you do not need to uninstall first.
5. Reboot the workstation; this clears the old driver binding.
6. Re-scan the network. The LOGO! should now display its name and firmware correctly.

6.2 Downgrade the LOGO! firmware to FS:05

If the project constraints require LSC V8.3.1 (for example, the program was authored in V8.3.1 and uses a function block not yet ported to V8.4), downgrade the LOGO! firmware to FS:05. The downgrade is performed over Ethernet with the LOGO! in STOP mode.

1. Open the Siemens LOGO! 8 firmware V1.08.xx (FS:05) download.
2. Place the firmware file on an SD card and insert it into the LOGO!.
3. From the LOGO! menu, choose Card -> Firmware Update and confirm.
4. The LOGO! reboots twice; wait until the RUN LED is steady before removing the card.
5. Re-scan in LSC. The "Unknown" entry is replaced with the configured name and version.

6.3 Run two LSC versions side by side

Install LSC V8.4 in a separate folder (for example, C:\Siemens\LOGO_8.4) and keep V8.3.1 in the default location. The two versions use independent user profiles and project files; opening a V8.3 project in V8.4 prompts for an automatic upgrade. Use V8.4 for any LOGO! 8.3 / 8.4 BM with FS:06, and V8.3.1 for legacy FS:04 / FS:05 hardware.

7. Layer 3 Fix - Windows 11 Discovery Failure

When the firmware is in range and the network is healthy but the LOGO! still does not appear in the scan, the Windows 11 build is the suspect. Apply the following in order.

7.1 Confirm the build

Open Settings -> System -> About or run winver. Builds 22000 to 22620 (21H2 early) are the most affected. The issue is largely corrected from 23H2 (build 22631) onward.

7.2 Update LSC and the network driver

Reinstall LSC V8.4 (see Section 6.1). The installer registers s7oie9x64.sys and a Winsock layer that does not require raw Ethernet broadcast. The older s7oie7x64.sys used by V8.3.1 is the source of the regression on Windows 11.

7.3 Allow LOGO! Soft Comfort through Windows Defender Firewall

1. Open Windows Security -> Firewall & network protection -> Allow an app through firewall.
2. Click Change settings and then Allow another app.
3. Browse to C:\Program Files\Siemens\LOGOComfort\LOGOComfort.exe and add it for both Private and Domain profiles.
4. Allow inbound UDP port 1354 and TCP port 102 explicitly using an inbound rule.

7.4 Disable user-mode network stack filters

Third-party VPN clients (Cisco AnyConnect, Palo Alto GlobalProtect, Zscaler) and some endpoint protection agents install LSPs that block the raw broadcast. Temporarily disable them and re-scan. If the LOGO! appears, add an explicit firewall allow rule for the VPN/PAP filter or move the LSC PC outside the tunnel.

7.5 Use a direct Ethernet crossover cable

Some managed switches strip broadcast frames in the discovery window. Connect the LOGO! directly to the PC with a crossover cable (or use Auto-MDIX on a modern switch port). This eliminates the switch as a variable and confirms the discovery path.

7.6 Last resort - roll back to Windows 10

If the project deadline is hours away and no update path is feasible, rolling back to Windows 10 within the 10-day return window is documented in the field case. Run Settings -> System -> Recovery -> Go back. The PC retains all applications and project files. The PC is online within approximately 30 minutes.

8. Diagnostic Flow Diagram

9. Verification Checklist

After applying any fix, perform the full verification before resuming commissioning. Each item is a hard gate.

10. Troubleshooting Matrix

The following matrix maps the most common user-reported symptoms to the most likely cause and the recommended action. Use it as a quick triage table on a service call.

11. Network Configuration Reference

The following IP and protocol parameters must match between the LOGO!, the PC, and any managed switch. Inconsistent values are the second most common cause of "Unknown" after the firmware mismatch.

11.1 Static IP assignment on the LOGO!

1. From the LOGO! display press ESC then navigate to Network -> IP Address.
2. Enter the address (for example 192.168.1.50).
3. Enter the subnet mask (255.255.255.0).
4. Enter the gateway (192.168.1.1) if cross-subnet access is required.
5. Press OK to commit. The LOGO! reboots the SMI service within 5 seconds.

11.2 Static IP assignment from the web server

1. Open http://<current-IP> and log in.
2. Choose System -> Ethernet.
3. Uncheck Obtain IP address automatically (DHCP).
4. Enter the new IP, mask, and gateway. Click Set Values.
5. Wait for the LOGO! to confirm the change. The browser session is lost; reconnect to the new IP.

12. Field Commissioning Notes

• Always export the LOGO! program to PC before any firmware change. The export uses the .lsc file format. A V8.3.1 export opens in V8.4 after a one-time auto-upgrade.
• Do not run LOGO! Soft Comfort inside a Remote Desktop Services session. The s7oie driver requires direct access to the NDIS stack. Tunnel the network connection to the PC and run LSC locally instead.
• Avoid running two LSC instances on the same PC. Two instances bind to port 1354 and one will fail to receive discovery responses. The newer LSC version should be opened first.
• SD card notes. Always use Siemens-approved SD cards (order 6ED1057-1AA00-0BA0) up to 8 GB. FAT32 formatting is mandatory. Larger cards (64 GB) may not be recognized by the LOGO! 8 BM.
• Keep a recovery SD card. A card with a known-good program and the FS:05 firmware is the fastest way to recover a bricked module on site.
• Document the LOGO! name in the plant asset register. The name is the primary key for LSC discovery across the plant. Reusing the same name on two LOGO!s causes LSC to alternate between them during scans.
• Security: change the default web password. The default LOGO/LOGO credentials are well-known. Set a strong password from the web UI or the LSC Tools -> Options -> Access tab.
• Avoid LSC V8.3.1 on Windows 11 24H2. Microsoft's 24H2 build removed the legacy NDIS path entirely; V8.3.1 will not see any device even if the firmware is supported.
• Use a UPS on the engineering PC. A power loss during a firmware update through LSC can leave the LOGO! in an unrecoverable state. The SD-card method is the only safe path if the UPS is not available.

13. Safety and Standards Notes

The LOGO! 8 family is listed for industrial control use under IEC 61131-2. Any modification to firmware or LSC version that touches a safety-related function block (for example, the LOGO! Safety variant FS:04 with the safety license) must be processed through the plant's functional-safety change-management procedure. Do not downgrade a LOGO! Safety module without an updated safety case; the older firmware may not carry the same SIL rating as the deployed one. Refer to the LOGO! 8 system manual, chapter 11, for the SIL classification table and to IEC 61131-2 for the environmental envelope.

14. Frequently Asked Questions