Fixing S7-1200 Error 0050-133 2 2458 Hardware Download Failures

Problem Description

The TIA Portal download to a SIMATIC S7-1200 CPU terminates with the dialog "Loading the hardware configuration failed" and the structured error code (0050-133 2 2458). The error appears during the hardware-configuration write step, not the user-program compile. After the failure, the project tree in TIA Portal reports zero compile errors and zero warnings, the project compiles cleanly, and a freshly created project containing only the CPU and a single instruction in OB1 reproduces the fault on the first download. The PLC is reachable on the engineering subnet but no configuration or program block can be written to it; the on-board load memory is effectively empty from the engineering perspective.

Field reports show the failure on the following catalog numbers and firmware revisions:

The same error has also been reproduced on a duplicate, factory-fresh CPU of identical part number, ruling out a single-unit hardware defect in many cases. Two failure modes must therefore be distinguished:

1. Recoverable – the CPU responds to "Online & diagnostics" and accepts a memory-card format or factory reset.
2. Non-recoverable – the CPU reports "incompatible device" on connection or rejects "Reset to factory settings" with the dialog "Module could not be reset to factory settings". In this mode, the MAINT LED is steady-flashing, the IP address is locked, and a START command leaves the CPU in STOP.

Error Code Decomposition

Siemens download errors are returned in the form (tttt-ddd p eeee). Each segment maps to a specific phase of the TIA Portal download sequence:

The CPU signals the rejection by setting the internal "configuration invalid" flag and triggering the MAINT LED. The same internal flag is what causes the factory-reset path to return "Module could not be reset to factory settings" – the CPU is protecting a load-memory area it considers inconsistent with its current firmware personality.

Root Cause Analysis

The 0050-133 2 2458 error is generated when the SDB container written by TIA Portal cannot be interpreted by the runtime firmware on the CPU. Four distinct causes have been confirmed in the field:

Cause 1 – Firmware/TIA Portal version mismatch

When a project created in TIA Portal V11 or V11 SP2 is downloaded to a CPU whose firmware is V3.0.1, the SDB structure generated by the older HSP set is not accepted by the newer firmware's loader. Siemens released a firmware update (V3.0.2) specifically fixing the load handshake for V11-generated HWCNFIG blocks. Reference: Operating System Update for SIMATIC S7-1200 CPU Firmware V3.

Cause 2 – Corrupted load memory after interrupted update

An aborted firmware update or a power-loss during a previous download can leave the internal flash file system in a state where the SDB region is unreadable. The CPU is then unable to read its own system data, blocks both new downloads and factory reset, and locks the IP stack. This is the failure mode that produces the persistent MAINT-flash behavior.

Cause 3 – MLFB / catalog-number mismatch

If the project hardware configuration uses a different catalog number than the physically connected CPU, the firmware personality block in the SDB is rejected. This is most common when a project is moved from one engineering station to another with a different HSP set, or when the engineering tool was upgraded but the project was not re-detected.

Cause 4 – SIMATIC memory card issue

On S7-1200 CPUs, all program and configuration data is stored on the external SIMATIC MC (or in internal load memory for cardless operation). A card with a corrupted file system or a card that was last programmed by a different firmware generation will produce a SDB-write reject identical to 2458.

Pre-Diagnostic Procedure

Before applying any recovery action, capture the following data. The values are required to differentiate between a firmware-mismatch recovery and a hardware RMA.

1. Open TIA Portal and select Online → Accessible devices.
2. Note the detected CPU's MLFB, firmware version, and IP address.
3. Right-click the device and select Online & diagnostics.
4. Open Diagnostics buffer and export the full event list as a text file.
5. Open Diagnostics → Cycle time / Memory and record the load memory and work memory used versus available.
6. Compare the detected MLFB exactly to the MLFB in the project tree's Device view.
7. Verify the PG/PC interface IP is in the same subnet as the CPU. Use ping <CPU IP> to confirm reachability.

Resolution Path A – SIMATIC Memory Card Format

This is the fastest recovery for Cause 2 and Cause 4. It requires the CPU to still respond to "Online & diagnostics", which means the loader is partially functional and the SDB region can be rewritten from the engineering tool.

1. In TIA Portal, click Go online with the configured CPU as the target.
2. Open Project tree → the CPU → Online & diagnostics.
3. Select Functions → Format memory card.
4. Confirm the prompt. The CPU will perform a logical format of the SIMATIC MC and reset the load memory to a clean state.
5. Power-cycle the CPU (off, 5 s, on). Wait until the RUN/STOP, MAINT, and LINK LEDs complete their startup sequence.
6. Click Go offline, then Download to device. Select Hardware and software (only changes) on the first attempt.

Resolution Path B – Factory Reset

Use this path when the project is stored in internal load memory, when no SMC is present, or when the format function is unavailable.

1. Open Online & diagnostics for the online CPU.
2. Navigate to Functions → Reset to factory settings.
3. Select Delete IP address if the CPU is on a non-standard subnet and you need to re-detect it.
4. Click Reset and confirm the prompt.
5. Wait for the CPU to return a success message. If the dialog reports "Module could not be reset to factory settings", stop and proceed to Path C – the load-memory region that holds the firmware personality is corrupted and the CPU will not accept a user-level reset.

On a clean factory reset, the CPU:

• Clears the load memory and work memory.
• Resets the IP address to 0.0.0.0 (if the option was selected).
• Removes the password protection.
• Returns all I/O to their default state.

After a successful reset, configure a new IP address via Online & diagnostics → Functions → Assign IP address or via the SIMATIC Automation Tool, then re-attempt the full download.

Resolution Path C – Firmware Update to V3.0.2 or Later

Apply this path when both A and B have failed, or when the diagnostic buffer shows firmware-related events preceding the 2458 error. The Siemens firmware update package for S7-1200 V3 includes the SDB-loader fix that resolves the original 0050-133 2 2458 condition.

1. Download the firmware update package from Siemens support entry 64789124. The package contains S7_1200_CPU_FW_V302.update or later.
2. Prepare a SIMATIC memory card (min. 4 MB) by copying the .update file to the card root. The card must be empty of project data.
3. Insert the card into the powered-off CPU.
4. Power on the CPU. The firmware update runs automatically; the MAINT LED will flash rapidly during the update.
5. Wait for the update to complete (typically 30 to 90 s). The CPU will restart automatically.
6. Remove the card and re-insert a project card (or leave the CPU in internal-load mode).
7. Re-attempt the project download.

Resolution Path D – RMA / Hardware Replacement

Field experience shows that on a small fraction of CPUs the 2458 condition is not recoverable at the engineering layer. Symptoms that force this path:

• CPU reports "incompatible device" the moment a connection is attempted.
• "Reset to factory settings" returns "Module could not be reset to factory settings".
• MAINT LED is steady-flashing, IP cannot be reset, START command is ignored, CPU stays in STOP.
• Diagnostic buffer shows a hardware-fault entry (event ID 0x03xx / 0x05xx) preceding the 2458.

Procedure:

1. Capture the diagnostic buffer export, the screenshot of the error, and the project snapshot.
2. Open a support request via Siemens Industry Online Support with the captured data and the order number.
3. Request an RMA. Siemens will replace the unit if the failure falls inside the warranty window and the diagnostic buffer confirms a hardware fault.

MAINT LED Recovery Procedure

The MAINT LED is the fastest on-machine indicator of the 2458 state. Interpretation table:

Verification Steps

After any resolution path, run the following checks before declaring the CPU recovered.

1. Online connectivity: Use Online → Accessible devices and confirm the CPU appears with the correct MLFB and firmware.
2. Diagnostic buffer clear: Open the diagnostic buffer and confirm no new "SDB write rejected" or "configuration invalid" events are appended.
3. Project download: Perform a full download (hardware + software). The transfer dialog should complete without the 0050-133 2 2458 error.
4. Online compare: Use Online → Compare offline/online and confirm 100% match on the CPU configuration and all loaded blocks.
5. Operating mode: Switch the CPU to RUN via Online & diagnostics → Functions → Start CPU and verify it remains in RUN for at least 5 minutes with the user program executing.
6. MAINT LED state: Confirm the MAINT LED is off or in the slow-flash maintenance state, not the fast-flash load-memory error state.
7. Memory card integrity (if used): Remove the SMC and read it on a PC with a Siemens card reader to confirm the project directory is intact.

Preventive Measures

The 2458 condition is rarely a one-time event. Apply the following controls on machines already recovered:

• Pin the TIA Portal version used for commissioning in the project documentation. Do not allow the engineering station to auto-update TIA Portal independently of the firmware revision on the controlled fleet.
• Maintain a version matrix of TIA Portal SP ↔ CPU firmware ↔ HSP set. The matrix must be approved before any project is downloaded to a production CPU.
• Always perform a controlled power-down (CPU in STOP, wait for the MAINT LED to settle) before removing a SIMATIC memory card.
• Store at least two spare, blank, Siemens-branded SIMATIC MCs on site. Field experience shows the recovery time drops from hours to minutes when a clean card is available.
• Use the S7-1200 programming manual download procedure to confirm memory-capacity compatibility before any download. A load that exceeds the CPU's available load memory produces a different error (typically 0050-133 1 xxxx) but is often confused with the 2458 condition.

Cross-Reference with Related S7-1200 Download Errors

Engineers often confuse 0050-133 2 2458 with adjacent codes. The differentiation matrix:

FAQ