Resolving Siemens LOGO! 8 Download Window Closes on Transfer

Problem Statement

When initiating a project download from LOGO! Soft Comfort (LSC) to a Siemens LOGO! 8.1 logic module, the transfer dialog appears to start normally. The LSC engineering tool resolves the accessible LOGO! on the local Ethernet network, the user confirms the target device, and the connection progress indicator begins. Within 1-2 seconds, however, the download window closes abruptly without raising a numeric fault code, a transfer-completion message, or a final error dialog. No program block is written to the LOGO! target. The reverse direction (upload from LOGO! to PC) typically does prompt for a password, confirming that the TCP/IP link between the PC and the LOGO! is healthy and that the issue is one-sided: it occurs strictly on the PC-to-device transfer path.

The reproducible behavior described above is observed on a Siemens LOGO! with order number 6ED1052-1HB00-0BA8 running firmware 1.81.03, which is a LOGO! 8.1 FS06 device. The problem is independent of the host PC IP address, the LOGO! IP address, or the subnet mask, and it is not caused by an Ethernet cabling fault. The root cause is a version mismatch between the LOGO! Soft Comfort version installed on the engineering PC and the LOGO! Functional State (FS) that was selected in the project hardware configuration.

Affected Hardware and Firmware Identification

Before applying any corrective action, you must positively identify the part number and firmware of the LOGO! module in service. The Siemens MLFB (order number) of the device in the case described is 6ED1052-1HB00-0BA8. The Siemens LOGO! 8 System Manual, edition 06/2024 decodes this number as follows:

The on-device firmware release displayed on the LOGO! built-in HMI under Menu → Diagnostics → FW Version, or reported by LSC under Tools → Transfer → LOGO! Status, is 1.81.03. The firmware decoder is: major.minor.revision = 1.81.03. Major 1 indicates a LOGO! 8.x family; minor 81 indicates a LOGO! 8.1 generation; revision 03 is a build number within the 8.1 branch. Combined with the order number, the device is therefore unambiguously a LOGO! 8.1 FS06 (Functional State 06).

Root Cause: LSC Version vs. LOGO! Functional State

LOGO! Soft Comfort versions map to the LOGO! Functional States they can program as follows:

The PC in the case study was running LSC V8.0. That release predates the LOGO! 8.1 FS05/FS06 hardware generation. When LSC V8.0 attempts a download to a LOGO! 8.1 FS06 target, the engineering tool cannot assemble a valid firmware-compatible program image. LSC terminates the transfer handshake after the initial TCP session is opened (the reason the dialog appears to start, then closes within 1-2 seconds) and the connection is dropped silently on the LSC side rather than the LOGO! side. The upload path uses a different protocol segment (the device-initiated block read), which is forward-compatible, hence the password prompt and successful read.

This is not a network problem. The connection handshake completes, the LOGO! responds to ARP and to LSC's discovery, and the transfer socket opens — the failure is at the application layer where LSC refuses to push a program to a target whose functional state was unknown at the time of the LSC build.

LOGO! 8 Functional State Reference

The functional state system was introduced to let Siemens ship hardware revisions with revised silicon, expanded I/O capabilities, or modified firmware feature sets while preserving a common order number. Cataloging FS separately from the order number allows Siemens to keep delivering the same MLFB through lifecycle phases without invalidating installed bases. The relevant FS indices for LOGO! 8.x modules are:

When you select a hardware in LSC under File → Properties → Hardware, the catalog entry you choose should match the FS that LSC can actually compile for. LSC V8.0 only offers the LOGO! 8.0 FS04 catalog, which is why selecting that entry on a FS06 target produces a non-functional download attempt.

LOGO! Soft Comfort Compatibility Matrix

The compatibility between LSC and the LOGO! module goes beyond version numbers — the catalog selected inside the project must be matched to the FS of the physical device. The matrix below summarizes the combination that triggers the "window closes in 1-2 seconds" failure mode:

Pre-Update Network Configuration Validation

Before changing the LSC version, validate the existing PC <-> LOGO! Ethernet link. The user's configuration was correct and is reproduced here as a working reference baseline:

Verify the connection from a Windows command line on the PC:

C:\> ping 192.168.0.5

Pinging 192.168.0.5 with 32 bytes of data:
Reply from 192.168.0.5: bytes=32 time=1ms TTL=64
Reply from 192.168.0.5: bytes=32 time=1ms TTL=64
Reply from 192.168.0.5: bytes=32 time=1ms TTL=64
Reply from 192.168.0.5: bytes=32 time=1ms TTL=64

Ping statistics for 192.168.0.5:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)

If ping fails, fix the network layer first. LSC uses standard port TCP/8443 (HTTPS) for the LOGO! webserver and UDP broadcast for device discovery on the local subnet. The required topology is a point-to-point cable, a switch, or a router — but both ends must share the same subnet.

Step-by-Step Resolution Procedure

The confirmed fix in this case is to upgrade LOGO! Soft Comfort to a release that supports the LOGO! 8.1 FS06 catalog and to reselect the hardware inside the project. Follow the steps below in order.

1. Identify current LSC installation. Launch LSC on the engineering PC and click Help → About. Record the version. If it reads 8.0.x or earlier, proceed. If it reads 8.1.x or 8.2.x, skip to step 4.
2. Download the current LOGO! Soft Comfort release. Navigate to the official Siemens support portal entry for LOGO! Soft Comfort. The package is delivered as a 32-bit and a 64-bit Windows installer. Confirm whether the host OS is 32-bit or 64-bit (Win+X → System → System type). The download link is documented in the Siemens LOGO! Soft Comfort V8.3 product information page.
3. Install the upgrade. Run Setup.exe as Administrator. The installer is an MSI-based bundle; right-click → Run as administrator is required for the USB driver and the firewall rule to register correctly on Windows 10/11. If you are using a demo version of LSC, the upgrade may be blocked — in that case, register a full license first or use a separate licensed PC.
4. Verify the installed version. Re-open LSC, click Help → About, and confirm that the new version is 8.1.x, 8.2.x, or 8.3.x. The case study ended with LSC V8.2, which fully supports LOGO! 8.1 FS06.
5. Reselect the hardware inside the project. In LSC, open the project (.lsc / .lma) that was failing to download. Click File → Properties. In the Hardware tab, change the LOGO! selection from the wrong FS to LOGO! 8.FS4 (Standard) — or, in LSC V8.2+, you may instead see a specific LOGO! 8.1 (0BA8.Standard, FS06) entry. The exact label varies with the LSC release; the key point is that the device you choose must match the FS of the physical hardware. Click OK.
6. Re-initiate the transfer. Click Tools → Transfer → PC → LOGO! (or the toolbar download arrow). LSC will scan the subnet for accessible LOGO! modules. Select 192.168.0.5 and confirm.
7. Enter the LOGO! password if prompted. The target LOGO! will request the program-protection password. Enter the existing password and confirm.
8. Confirm the transfer. The progress dialog should now run for several seconds (the duration depends on the size of the LSC program), reach 100%, and close with a success message. The on-device HMI will show the running program.

Hardware Selection Within LOGO! Soft Comfort

The hardware selection dialog inside LSC is the single most common source of mismatches in the field. The dialog lists the LOGO! catalog entries that the current LSC version knows how to compile for. The case study user selected "LOGO! 8.FS4" (a 0BA8 Standard, FS04 catalog item) for a LOGO! 8.1 FS06 device. Because the FS04 catalog predates FS06, the LSC compiler emits a program image that the FS06 firmware cannot ingest. The transfer engine in LSC therefore aborts before sending any user-relevant data, which produces the empty 1-2 second failure mode.

The correct selection is to match the FS of the hardware. Confirm the FS of the physical device using one of these methods:

• On the LOGO! built-in HMI: Menu → Diagnostics → FW Version shows the major.minor.revision, which you can map to the FS via the table in this article.
• From LSC, while connected: Tools → Transfer → LOGO! Status reports the FS directly.
• From the LOGO! webserver, if the network is up: navigate to http://192.168.0.5 in a browser; the home page shows the firmware and FS.

Then, in the LSC project properties, choose the catalog entry whose name string contains the matching FS suffix.

Network Topology and Direct-Connection Reference

The case study uses a direct PC ↔ LOGO! Ethernet link. The reference topology is:

The 192.168.0.0/24 subnet is the historical Siemens LOGO! default. Both modern PCs and LOGO! devices auto-negotiate MDI/MDX, so either a crossover or a straight-through patch cable will work.

Verification of Successful Download

After the corrected transfer completes, perform the four-point verification below to confirm that the new program is running correctly on the LOGO! 8.1 FS06 hardware.

1. Transfer status dialog in LSC closes with "Transfer successful" or equivalent.
2. LOGO! HMI shows the program name and the green RUN LED on the front of the device is on solid.
3. Inputs/outputs toggle as expected when the field wiring is exercised. The on-board relay outputs of the 6ED1052-1HB00-0BA8 are Q1..Q4.
4. Webserver at http://192.168.0.5 shows the current variable status reflecting the new program.

Field-Proven Diagnostics for Recurring Download Failures

The failure described in the source case is the most common but not the only silent transfer abort. Use the following diagnostic matrix when the download window closes or when a download never starts.

Security software interference is a known cause of application-layer silent aborts. Endpoint protection suites that inspect local process network traffic (including Windows Defender, Kaspersky, ESET, and Bitdefender) can interrupt the LSC transfer socket mid-handshake. As a related failure class, browsers and download managers have tightened transport security, so the LSC installer download itself can fail in obscure ways. The general rules of thumb for the installer download (not the LOGO! program transfer) are:

• Use Firefox or Chrome on a stable HTTPS link, and disable "Enhanced Safe Browsing" downloads if you see the LSC installer disappear after clicking.
• Verify the file size matches the Siemens portal listing before executing — partial downloads produce the same abort-after-1-2-second pattern when run.
• Run the installer as Administrator so that the firewall rule and the USB driver register correctly.

The browser-related references — Mozilla's Firefox antivirus interference KB, Google's Chrome HTTP download block thread, and Microsoft's Edge "save as" dialog KB — cover the installer fetch, not the LOGO! transfer itself. They are listed here because operators frequently confuse the two failures during the upgrade cycle.

Common Pitfalls and Edge Cases

Several recurring conditions trip up field engineers working with LOGO! 8.x. Each is documented below with the canonical fix.

Mixing LOGO! generations in a project. If you have several LOGO! devices in service — some LOGO! 7 (0BA7), some LOGO! 8.0 FS04, and some LOGO! 8.1 FS06 — you must maintain a separate LSC project for each. LSC will refuse to load a project whose hardware selection does not match the catalog, and will refuse to download it to a different FS even if the I/O pattern looks compatible.

Firmware downgrades. Once a LOGO! 8.1 FS06 device has been flashed with a V8.2+ LSC project, you cannot revert the LOGO! to V8.0 program images. The LSC V8.0 catalog does not include FS06. Keep a backup of the running LSC V8.2+ project on a network share so that recovery does not require a second upgrade cycle.

Subnet drift after direct connection. The default Siemens LOGO! 8.x IP is 192.168.0.5/24. If your PC connects to a corporate network with DHCP and ends up on a 10.x or 172.16.x subnet, the LSC browser cannot see the LOGO!. Set the PC to a static 192.168.0.x address for the duration of the transfer, or add a route in the Windows routing table.

USB Ethernet adapter MAC randomness. Some USB-Ethernet adapters randomize their MAC on every cold boot, which causes ARP cache flapping on the LOGO!. Use the on-board Ethernet port of the laptop for the engineering connection whenever possible.

Old project re-opened after LSC upgrade. A project created in LSC V8.0 retains its V8.0 hardware selection when opened in LSC V8.2. The catalog is preserved in the project file. You must explicitly reselect the FS in File → Properties → Hardware before downloading, even after the LSC upgrade. This is the silent second trap that catches operators after they complete the upgrade and assume the issue is fixed.

Demo version block on upgrade. Demo versions of LSC cannot be upgraded in place. If the case study PC had been running a demo, the installer would have refused. Confirm the license status in Help → About before starting the upgrade.

Frequently Asked Questions