LOGO! 8.3 SD Card Load Fails Fixing LSC 8.4 Program Compatibility

Problem Overview: SD Card Transfer Restarts But the Program Never Updates

Engineers working with the Siemens LOGO! 8 generation (0BA8) frequently encounter a confusing behavior when transferring a program from a micro-SD card to a physical LOGO! 8.3 base module. The device restarts the moment the operator selects the "Load program from SD card" entry from the LOGO! onboard menu, yet the new program never appears in the device's program memory. Re-running the same transfer over Ethernet from LOGO!SoftComfort (LSC) succeeds without issue, and the operator is left believing the SD card itself is faulty.

This symptom is not a card failure and is not a hardware defect on the LOGO! 8.3 module. It is a firmware-metadata mismatch between the version of LOGO!SoftComfort used to author the project and the firmware running on the target LOGO! base module. The exact combination that triggers the issue is:

• LOGO!SoftComfort 8.4 (or newer) is used to author or last-save the project.
• The target device selected in the LSC project header is "LOGO! 8.4 (0BA8.04)" or higher.
• The physical LOGO! base module is a LOGO! 8.3 (0BA8.03) or earlier 0BA8 device.
• Program transfer is attempted via micro-SD card rather than Ethernet.

Root Cause: Firmware Version Metadata Embedded in LSC Projects

Every .lsc and .lgo file written by LOGO!SoftComfort contains a small header block that records the target hardware (0BAx) and target firmware revision (8.0, 8.1, 8.2, 8.3, 8.4). This block is invisible in the LSC editor and is not exposed to the user, but the LOGO! bootloader reads it before it accepts the program into flash memory.

Behavior matrix when the header target is newer than the device firmware:

When the LOGO! 8.3 bootloader sees a header it does not recognize, it does not display an error code. It simply refuses the program, the internal flash remains empty (or contains the prior project), and the device performs a normal restart. The operator sees a green LED, a brief boot screen, and is returned to the main menu exactly as before — the classic signature of a silently rejected SD card transfer.

Identifying Your LOGO! 8.x Hardware and Firmware

Before applying any fix, confirm the exact generation and firmware revision of both the LSC project and the physical device. Mismatches at the <0.1> level are still real mismatches and will produce this symptom.

Reading the Order Number (MLFB)

The Siemens order number printed on the front of every LOGO! 8 base module encodes the hardware generation in the suffix:

Common 0BA8 part numbers for reference:

• 6ED1052-1CC08-0BA1 — LOGO! 12/24 RCE (relay out, Ethernet)
• 6ED1052-1MD08-0BA1 — LOGO! 24CE (transistor out, Ethernet)
• 6ED1052-2CC08-0BA1 — LOGO! 230 RCE (relay out, mains-powered)
• 6ED1052-1HB08-0BA1 — LOGO! 24 RCEo (no display)
• 6ED1052-2FB08-0BA1 — LOGO! DM8 230 R expansion

Reading Firmware on the LOGO! Onboard Display

1. With the LOGO! powered and in run/stop, navigate: Menu → Diagnostics → Product Information (or System → FW Version depending on LSC version).
2. Record the values of FW Version, HW Version, and Boot Loader.
3. Cross-check against the printed part number on the right side of the module.

Reading the Project Target in LOGO!SoftComfort

1. Open the project in LSC 8.x.
2. From the menu bar choose Tools → Select Hardware (or File → Properties → Hardware).
3. Note the selection: 0BA8 Standard, 0BA8.FS02, 0BA8.FS03, 0BA8.FS04.
4. The selection shown here is the value embedded in the SD card header. If it is newer than the device firmware, the SD card transfer will fail as described.

SD Card Boot Behavior and Memory Loading Sequence

Understanding the loading sequence clarifies why the LOGO! appears to "restart every time" you select the menu entry and why the program never persists.

Key behavioral rules of the LOGO! 8.3 SD card path:

1. One-shot copy on first boot. When an SD card containing a valid .bin (or .lgo) is inserted and the LOGO! is power-cycled, the bootloader copies the file into internal program memory exactly once. The green LED blinks during the copy and becomes solid when complete.
2. Card-resident restart loop. If the project flag "Copy program to LOGO! memory and run it from there" is not set, the LOGO! will re-read the card on every power-up. This is by design: it is the field-replacement mode for a fleet of identical machines. If the card is the only valid source, the device will only ever boot from the card.
3. Bootloader rejection is silent. The LOGO! 8.3 bootloader does not log or display a "wrong firmware target" error. It simply discards the file, boots from the existing internal program, and the operator sees only the restart.
4. Card removal after first copy is safe. Once the program is in internal flash, you can remove the SD card and the LOGO! will continue to run from internal memory on subsequent restarts.

Step-by-Step Diagnostic Procedure

Run this sequence before applying any fix. Each step isolates one variable so the root cause is confirmed rather than assumed.

1. Confirm the device firmware version. Read it from the LOGO! onboard display under Diagnostics → Product Information or via LSC menu Tools → Connect → Identify LOGO!. Record FW, HW, and order number.
2. Confirm the project target. In LSC, open Tools → Select Hardware and note the value (0BA8 Standard, 0BA8.FS03, 0BA8.FS04, etc.). Compare with the device firmware from step 1.
3. Confirm the SD card file. Power off the LOGO!, remove the SD card, insert it into a PC. Look for a folder named /LOGO/ containing a single .bin (and optionally a .lsc). The .bin is what the LOGO! 8.3 bootloader actually reads.
4. Test the same project over Ethernet. Use LSC Tools → Transfer → PC → LOGO!. If this succeeds but the SD card path does not, the firmware-mismatch root cause is confirmed.
5. Test with a known-good SD card program. Save a program that was authored in LSC 8.3 (or with the target explicitly set to 0BA8.FS03) to a separate SD card and attempt the load. If this works, the hardware and SD card are good; the original project is the issue.
6. Verify SD card file system and size. LOGO! 8.3 supports FAT16 and FAT32. Maximum supported card size is 32 GB. Cards larger than 32 GB are silently ignored by the bootloader. Reformat the card as FAT32 with 32 KB cluster size if in doubt.

Resolution 1: Rebuild the Project Against the Correct Target

The cleanest fix is to make the LSC project match the physical device.

1. Open the project in LOGO!SoftComfort.
2. Go to Tools → Select Hardware and choose the device target that exactly matches the physical LOGO!. For a LOGO! 8.3 base module, select 0BA8 Standard (which is a forward-compatible 0BA8 target) or the explicit 0BA8.FS03 entry if your LSC version exposes it.
3. Avoid features that did not exist in the older firmware (see the compatibility table below).
4. Recompile (F7 or File → Compile).
5. Transfer to SD card: Tools → Transfer → PC → SD Card. The card must be inserted in the PC's SD slot or a USB reader.
6. Move the SD card to the LOGO!, power cycle, wait for the green LED to become solid (~5 to 15 seconds), then remove the card.
7. Verify with Tools → Connect → Identify LOGO! in LSC, or read the program name on the LOGO! onboard display.

Resolution 2: Save As "LOGO! 8 Standard" for Downward Compatibility

If the LSC version installed on the engineering workstation is 8.4 or newer and you must support a fleet of 8.3 devices, configure the project to compile against the 0BA8 Standard target. The 0BA8 Standard target is recognized by every LOGO! 8.x bootloader, so the resulting .bin is portable across the entire 0BA8 hardware family.

1. Open the project, then File → Save As.
2. Choose LOGO! Project (*.lsc) and confirm.
3. Immediately re-select the hardware: Tools → Select Hardware → LOGO! 8 (0BA8 Standard).
4. Compile. If LSC flags a feature that is not supported on 0BA8 Standard, the FBD will mark the unsupported block in red. Remove or replace the unsupported feature.
5. Save, transfer to SD card, and deploy.

Resolution 3: Transfer via Ethernet First, Then Maintain With SD Card

For facilities that standardize on SD card cloning for fleet maintenance, you can still leverage the Ethernet path's negotiation to perform the initial transfer, then use the SD card only for the cloning use case.

1. Connect the LOGO! 8.3 directly to the engineering PC with a standard Ethernet patch cable (auto-MDIX supported on 0BA8).
2. Set the LOGO! IP to a known value via the onboard menu (Network → IP Address) or via DHCP reservation.
3. In LSC, Tools → Transfer → PC → LOGO!. The transfer succeeds because the LSC PC-side runtime negotiates the firmware target downward.
4. From the LOGO!, Card → Copy program to SD card. This creates a card-resident copy of the program that the device's own firmware has already verified.
5. Use the resulting SD card image for cloning to other LOGO! 8.3 devices.

This workflow is also the safest for first-time commissioning of a new cabinet where an Ethernet-connected laptop is available: the program is loaded via Ethernet, verified in run mode, and the SD card is produced as a maintenance backup from the running device rather than authored in LSC and pushed in.

Resolution 4: Power-Cycle and Remove the SD Card After Initial Boot

If the SD card path must be used and the project is already known-good, force a clean internal-memory copy and then physically remove the card.

1. Insert the SD card into the powered-off LOGO!.
2. Apply power. The LOGO! reads the card and copies the program to internal flash. The green LED blinks during copy and becomes solid when complete.
3. Power off the LOGO!.
4. Remove the SD card from the slot.
5. Apply power again. The LOGO! boots from internal flash. Verify the program name and that all I/O behaves as expected.

Resolution 5: Repair a Corrupted SD Card Image

If the SD card itself is the failure point — the card is recognized by the PC but not by the LOGO! — rebuild the card from scratch.

1. Back up any data on the card. Wipe the card with a full (not quick) format in SD Card Formatter 5.0.1 or later, set to FORMAT SIZE ADJUSTMENT ON.
2. Verify the file system. For cards up to 4 GB, FAT16 is acceptable; for 4 GB to 32 GB, FAT32 with 32 KB allocation unit size is recommended.
3. Create a top-level folder named LOGO (uppercase, no spaces).
4. Copy the project's .bin file from C:\Users\<user>\Documents\LOGO\<projectname>\ into the LOGO folder on the card. The .bin filename must be 8 characters or fewer with a 3-character extension to match the 8.3 filename convention of the LOGO! 8.3 bootloader.
5. Eject the card safely from the PC.
6. Insert the card into the LOGO! and power cycle.

LOGO! 8.x Feature and Firmware Compatibility Matrix

Use this table to decide which features must be removed or replaced when a project is targeted at a LOGO! 8.3 base module.

Verification: Confirming the Program Is Running From Internal Memory

After any of the resolutions above, run this verification sequence:

1. With the SD card removed, power-cycle the LOGO!.
2. On the onboard display, navigate to Menu → Program → Name. The displayed program name should match the deployed project.
3. Navigate to Menu → Diagnostics → Product Information and confirm the program count is incremented (LOGO! tracks internal program slots).
4. Use LSC Tools → Connect → Identify LOGO! to read back the program hash. The hash should match the LSC-side project hash.
5. Toggle an input on the LOGO! and verify the expected output behavior, including any timers or counters.
6. Power-cycle one more time. If the SD card slot is empty and the program still runs, the transfer is verified.

SD Card Best Practices for LOGO! 8.3

• Card capacity. Use cards from 512 MB to 8 GB for maximum compatibility. 16 GB and 32 GB cards from major brands (SanDisk, Kingston, Transcend) work in production but introduce longer boot times. Avoid cards larger than 32 GB.
• File system. FAT16 for cards ≤ 2 GB, FAT32 for cards > 2 GB. Always re-format in the official SD Card Formatter, never in Windows quick-format alone.
• Folder layout. Programs go in /LOGO/<NAME>.BIN and optionally /LOGO/<NAME>.LSC. Data logs go in /LOGO/<NAME>.LLD. Recipe files use /LOGO/<NAME>.LRT. Mixed root-level files confuse the bootloader.
• Filename rules. 8.3 filename convention (8 characters name, 3 characters extension). Upper or lower case is accepted. Do not use spaces or Unicode characters.
• Card brand. Industrial-grade SLC or pSLC cards (Swissbit, Apacer, Transcend H/W) are recommended for installations subject to vibration, temperature swings, or write-intensive data logging. Consumer SD cards are acceptable for static program storage.
• Write protection. The SD card slot on the LOGO! 8.3 has no write-protect lock tab in operation; the SD card must be physically write-protected (slider on the card adapter) if you need to prevent the LOGO! from overwriting your backup image.
• Hot insert/remove. The LOGO! 8.3 supports hot insert and hot remove of the SD card. The card must be re-recognized by the next power cycle if you want the LOGO! to re-read the root directory.

Common Pitfalls and Edge Cases

Three additional failure modes produce symptoms that look identical to the firmware-mismatch issue but have a different root cause. Verify these if the resolutions above do not resolve the problem.

Pitfall A: The "Load Program From SD Card" Menu Entry Re-Loads on Restart

If the SD card remains inserted and the program has the "Card → Copy program to LOGO! internal memory" flag disabled, selecting the menu entry does load the program into flash — but on the next power cycle the LOGO! reloads the same file from the card and overwrites any change. The operator concludes that the load did nothing. The fix is either to remove the SD card after loading or to enable the internal-memory flag in the LSC project and re-deploy.

Pitfall B: The Card Was Formatted ExFAT

Windows 10 and later default to exFAT for cards larger than 32 GB and often offer exFAT for smaller cards. The LOGO! 8.3 bootloader does not support exFAT. Reformat to FAT32.

Pitfall C: The Project Was Saved As "LOGO! 7" or Older

The reverse mismatch — a project saved for 0BA7 or earlier — is also rejected by the LOGO! 8.3 bootloader because the FBD block library and I/O addressing changed. The fix is to open the project in LSC 8.x and explicitly re-select 0BA8 Standard as the target, then recompile.

Pitfall D: Two .bin Files in /LOGO/

The bootloader scans /LOGO/ in alphabetical order and loads the first valid .bin it finds. If your card has a stale file from a previous project (for example, OLDPRJ.BIN and NEWPRJ.BIN), the LOGO! may load the old one. Keep exactly one .bin per card.

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