Siemens SINAMICS G150: Resolving "Fatal Error in Drive: AOP Stopped"

The Siemens SINAMICS G150 cabinet drive is a high-power, air-cooled AC drive family widely deployed in pumps, fans, compressors, mills, and extruders. Although mechanically robust, G150 systems depend on a healthy control platform consisting of a CU320-2 (or CU320) Control Unit, an AOP30 Advanced Operator Panel, and a CompactFlash (CF) card loaded with firmware, parameters, and option licensing. When the CF card develops bad sectors, the CU320-2 enters an unrecoverable state and raises the alarm "Fatal error in drive: AOP stopped" on the AOP30, which then locks and prevents normal operation. This reference explains the root cause, the diagnostic verification path, the field-proven fix (CF card replacement with part 6SL3054-1CE00-1AA0), and the recommissioning workflow that restores a 250 kW G150 cabinet to service.

1. Affected Product Range and Hardware Stack

The "Fatal error in drive: AOP stopped" message is observed on SINAMICS G150 chassis (order code 6SL3710-1LE4x-xxxx, 6SL3710-2LE4x-xxxx, 6SL3710-1LG4x-xxxx) populated with the following components:

The compact drive described in the field case is rated at 250 kW, which corresponds to a 6SL3710-1LE41-0AA0 chassis (400 V, 50/60 Hz, 460 A nominal). At this power class the G150 ships with a CU320-2 DP control unit, a type-30 AOP30 operator panel, and a single 6SL3054-1CE00-1AA0 CompactFlash card pre-imaged with the matching firmware build (typically V4.6, V4.7, or V5.x depending on commissioning era).

2. The "Fatal Error in Drive: AOP Stopped" Message: What It Means

The string "Fatal error in drive: AOP stopped" is generated by the CU320-2 firmware's boot-time exception handler when one of the following conditions occurs before the runtime firmware is fully initialized:

• The CF card returns a read or seek error during firmware load, preventing the operating image from being copied to volatile memory.
• The CF card's file system structure is corrupted to the point that the boot loader cannot locate fwu/ firmware images or the user/ parameter directory.
• The license signature blob on the CF card fails cryptographic verification, leaving the drive in a fail-secure state.
• The CU320-2 has an internal memory fault (much rarer) and references the CF card as the boot media of last resort.

When any of these conditions occur, the firmware aborts the boot sequence, halts the internal RT scheduler, and reports a single non-acknowledgeable fault to the AOP30. Because the AOP30 talks to the CU320-2 over a serial RS-232 PPI link, the AOP itself shows "AOP stopped" as a secondary indicator that the control unit is no longer transmitting heartbeats. The drive's main contactor (line contactor, K1) will not pull in, and the display will not respond to the RUN, STOP, or FAULT-ACK keys.

3. Root Cause: CompactFlash Card Degradation

In the reported field case, the root cause was conclusively traced to a faulty CompactFlash card, order number 6SL3054-1CE00-1AA0. CF cards used in industrial cabinets from the early 2010s onward are typically consumer-grade industrial-temperature SLC or pSLC NAND modules in a CFA-compliant form factor. They share a wear-leveling issue: while the average read/write duty of a CU320-2 is low (parameters are written primarily during commissioning and on parameter set save), the following stressors accelerate wear:

• Cabinet ambient temperature above 40 °C, with the CF card slot located close to the rectifier heat sink.
• Frequent parameter save/load cycles (e.g., recipe handling via p0804/p0805 on a process line).
• Uncontrolled power-downs that leave the FAT directory in an inconsistent state.
• High humidity / dust that contaminates the card-edge connector.
• Age: most industrial CF cards begin to develop read-disturb and bit-rot defects after 8-10 years in service.

When the CF card reaches end-of-life, the CU320-2 boot loader, which expects to read fwu/ and user/ partition images in a specific sequence, fails on the first read. The CU's internal watchdog triggers a fatal exception, and the user-visible message is produced.

3.1 Confirming the CF Card as the Suspect

Before replacing the card, perform these confirmatory steps. They save time when a less common cause is involved:

1. Power-cycle the cabinet with the line supply removed for at least 30 s. The CF card slot is hot-pluggable on the CU320-2, but for safety always remove the supply. Power-up again. If the same message returns, the fault is persistent (not a transient glitch).
2. Inspect the CF card by ejecting the ejector button on the CU320-2 front panel. Examine the card-edge connector for oxidation, dust, or bent pins. Reinsert firmly. Power up. If the fault returns, proceed to replacement.
3. Check the CU320-2 LEDs: RDY (green) should be steady on; COM (yellow) blinks on DRIVE-CLiQ traffic; OPT (red) is the option-fault LED. If RDY is off or flashing red, the CU is in fault - confirms the AOP message originates in the CU, not the panel.
4. Read the diagnostic buffer via STARTER or SIMOTION SCOUT if the project is still on a PG/PC. Connect via Ethernet (PROFINET) or PROFIBUS to X126 / X136. Read r0947 (fault code) and r0949 (fault value). Common codes associated with this scenario are F01000 (internal software error), F01002 (internal software error - boot), and F01300 (invalid firmware on the CF card).
5. Substitute the CF card with a known-good 6SL3054-1CE00-1AA0 from a healthy sister drive. If the drive boots, the original card is the confirmed root cause.

4. Solution: CompactFlash Card Replacement Procedure

Replacing the CF card on a SINAMICS G150 is a field serviceable operation, but it requires a controlled power-down and a recommissioning step. The new card must be loaded with firmware and parameters before the drive will operate.

4.1 Prerequisites

• Replacement CF card: 6SL3054-1CE00-1AA0 (for firmware ≥ 4.6) or 6SL3054-1CE00-1BA0 (for older firmware). The two are not interchangeable - match the firmware branch that was in service.
• STARTER commissioning tool (current version, e.g., V5.4 SP3 or later) or Startdrive for TIA Portal (V15.1 or later).
• Backup of the existing project on a programming device (PG/PC) - if available. If the original card is unreadable, this is the only way to restore parameters.
• Firmware image files (downloadable from Siemens Product Support under entry ID 109763072 for SINAMICS S120/G150 firmware).
• Access to the CU320-2 front panel and the ability to remove cabinet doors per local EHS rules.
• Personal protective equipment rated for the cabinet's line voltage (typically 400 V or 690 V).

4.2 Replacement Steps

1. Lockout-tagout (LOTO) the main line supply. Verify absence of voltage at the line terminals with a CAT IV 1000 V tester. Wait the prescribed 5 minutes for DC bus capacitors to self-discharge. Open the cabinet front door.
2. Locate the CU320-2 module in the cabinet door, typically bottom-right. Identify the CF card slot with the orange/yellow ejector button.
3. Press the ejector button. The old CF card will partially eject. Pull it straight out - do not angle.
4. Insert the new 6SL3054-1CE00-1AA0 card with the label facing the same direction as the original. Push firmly until the ejector button clicks back into flush position.
5. Close and latch the cabinet door. Restore line supply. Power up the cabinet.
6. The CU320-2 will boot from a blank CF card into a safe state with default parameters and a "Commissioning required" prompt on the AOP30.

4.3 Loading Firmware and Parameters

Use one of the following methods to put the new card back into service.

4.3.1 Method A: Restore from PG/PC Project Backup (preferred)

1. Connect a PG/PC to the CU320-2 X127 service port or to X126 (PROFINET) on the cabinet. Set the PG to the same subnet (e.g., 169.254.11.22 with mask 255.255.0.0).
2. Open STARTER. Open the project archive (.zap) that was backed up from the original drive.
3. Go online to the CU320-2. Right-click the drive object and select Download to Target System. STARTER will push the project (parameters, BICO interconnections, fault settings) to the CU.
4. Save the parameters to non-volatile memory with p0977 = 1 (or by clicking Copy RAM to ROM). This writes the parameter set to the new CF card.
5. Cycle power one more time. The drive will boot with the restored parameters.

4.3.2 Method B: Card-to-Card Image Restore (if backup is on another identical card)

1. If a sister drive's CF card is available and is the same firmware version, remove that card and use a CF card reader/writer to clone it with a tool such as Win32 Disk Imager or dd on Linux. Write the image to the new 6SL3054-1CE00-1AA0.
2. Insert the cloned card into the G150 CU320-2. Power up. The drive will boot with the cloned parameters.
3. Verify all parameters - especially license-dependent features (e.g., Safety Integrated, performance extensions) and the AOP30 layout block (p0700, p2051, etc.).

4.3.3 Method C: Re-commission from Default Parameters

If no project backup exists, the drive must be re-commissioned from scratch. Follow the G150 operating instructions in the SINAMICS G150 Operating Instructions manual entry on Siemens Product Support.

1. Use the AOP30 to walk through quick commissioning: p0010 = 1, set motor data (p0300, p0301, p0304, p0305, p0307), encoder data if present, and application macro (p0500 or P1300). Verify with p3900 = 1 (calculate motor data and reset to factory).
2. Save with p0977 = 1.
3. Test in jog mode (p0010 = 0, then use the AOP jog key or STARTER control panel).

5. Verification Checklist After Replacement

After the new CF card is in service and parameters are restored, perform the following verification sequence before returning the drive to the process.

1. Power-up the cabinet. Confirm the AOP30 displays normal operating screen - not the "Fatal error in drive: AOP stopped" message.
2. Check the CU320-2 LEDs: RDY green steady, COM green/yellow blinking, OPT off.
3. Read the diagnostic buffer (r0945[0..7]). Confirm no F01000/F01002/F01300 entries are present after the new card boot.
4. Verify the firmware version displayed on the AOP30 startup screen matches the expected version (e.g., V5.2.3 HF1).
5. Close the line contactor from the AOP30 (press RUN or the green ON key). Verify the contactor pulls in and the drive is in "Ready to Run" state (r899.0 / r899.1 indicators).
6. Run a no-load motor test in jog mode at low frequency (5-10 Hz) for 30 s. Listen for abnormal noise; check motor rotation direction.
7. Apply a closed-loop speed reference from the process controller. Ramp from 0 to 50 Hz over 30 s. Monitor output current and DC bus voltage on the AOP30 or STARTER trace.
8. Trigger a controlled emergency stop (OFF1 / OFF3) and verify the drive decelerates and the line contactor opens as designed.
9. Re-archive the project to the PG/PC with a timestamped filename (e.g., G150_S15037_2024-04-12_postCFreplace.zap). This protects against future media failure.

6. Why This Fault Pattern Emerges in 250 kW Class Drives

The 250 kW class G150 is a common capacity point for process-line drives in cement, water, and metals handling. These installations share characteristics that accelerate CF card wear:

• Cabinet ambient of 35-45 °C with limited HVAC conditioning.
• Long mean-time-between-maintenance intervals (typically 12-24 months).
• Frequent recipe changes (p0804 / p0805 parameter set switch) on batch processes, which trigger periodic parameter saves.
• Use of a single CU320-2 with no redundant control, so the CF card is a single point of failure.

For new builds, Siemens has moved to SINAMICS G150 with CU320-2 PN and newer CF cards (6SL3054-1CE00-1AA0, 6SL3054-1CG00-2AA0) with higher-grade NAND and extended operating temperature. For existing fleets, a preventive replacement interval of 7-10 years is a reasonable benchmark.

7. Diagnostics and Fault Code Cross-Reference

The following table maps the most common fault codes that surface on the AOP30 in the "Fatal error in drive: AOP stopped" scenario, with the recommended action. All codes are read from r0947/r0949 in STARTER or the AOP30 fault history.

For the specific case documented here, the G150 returned a single non-acknowledgeable fatal entry equivalent to F01000/F01002. A known-good CF card swap confirmed the original media as defective.

8. Preventive Maintenance Recommendations

To avoid recurrence of this fault, incorporate the following items into the site's PM program:

1. Annual parameter archive: Back up the project to a managed PG/PC and to a network share. Compare r0954 (operating hours) and r0046 (missing enable signals) trend over the year to detect anomalies before they become faults.
2. Cabinet environmental monitoring: Install a small temperature/humidity logger inside the cabinet. Keep ambient below 40 °C, humidity below 85 % non-condensing.
3. Proactive CF card replacement at 7-10 years: Order a fresh 6SL3054-1CE00-1AA0 in advance. Schedule a 30-minute swap during a planned downtime window. Use the swap to verify the project archive and to re-tighten CU320-2 connections.
4. Avoid forced power-downs during parameter save: After p0977 = 1, the CU320-2 writes to the CF card for 5-30 s. A power loss in this window can corrupt the file system. Add a UPS or a programmed delay between save and shutdown.
5. Keep a spare CF card on the spares shelf, pre-imaged with the current firmware, so that a swap can be performed in <15 min without waiting on a parts order.

9. Related Components Worth Inspecting

When the CF card swap is complete, use the same maintenance window to inspect components that share the same root-cause theme (age, temperature, vibration):

• CU320-2 backup battery: if present (some variants), a CR2032 lithium cell. Replace every 5 years to retain real-time clock through power-off.
• AOP30 cable and connector: the RS-232 cable to the CU is a frequent point of intermittent fault. Inspect for kinks and pin oxidation.
• Cabinet fans: confirm airflow is nominal. A failing fan raises the CF card's local temperature and accelerates media wear.
• DRIVE-CLiQ cables: check that all connectors to TM31, SMC, and the Power Module are fully seated. A loose DRIVE-CLiQ connector can produce related but distinct symptoms (F30611).

10. Quick Reference: Part Numbers and Tools

11. Field-Proven Caveats from the Source Case

The original 250 kW G150 took several days to resolve because the "Fatal error in drive: AOP stopped" message does not appear in the standard SINAMICS G150 fault list published in the operating instructions. Service technicians and even Siemens regional support had to reason by elimination. The key learning points from that case are reproduced here for future engineers:

• The fault is not generated by the AOP30. The AOP is the messenger, not the cause. Replacing the AOP30 first wastes time and budget.
• The fault is not a parameter issue. Acknowledging the fault with the AOP or with STARTER has no effect. The CU is in a permanent halt.
• The fault is not cleared by a power-cycle. Only a media change brings the CU320-2 back to a bootable state.
• The most efficient diagnostic path is to substitute a known-good CF card as the first step. If the drive boots with a spare, the diagnosis is complete in 5 minutes.
• After the swap, treat the new card's parameter set as the only surviving copy until a project archive is re-created. Lose the archive and the next fault requires a full re-commission.

12. FAQ