Recovering SIMODRIVE 611U from E-A001: Firmware Update Procedure

1. Overview

The Siemens SIMODRIVE 611 universal (611U) closed-loop control unit is used in conjunction with the SIMODRIVE 611 modular drive system for speed, torque, and positioning applications on machine tools and production machinery. Control units in the 6SN1118 family host the firmware card that determines the drive's functional behavior, safety logic, and feedback evaluation.

Order number 6SN1118-0NJ01-0AA0 is the resolver feedback (NJ) variant of the 611U control module. The closely related 6SN1118-0NH01-0AA0 is the encoder feedback (NH) variant. Mixing the two variants will cause immediate alarm conditions on first power-up, which is why the firmware card A5E00228755 (Version A) and the UFW file shipped with the matching control variant must be loaded together.

This document covers the recovery procedure when the 611U reports alarm E-A001 at power-up, the canonical cause being a corrupt or missing control firmware on the firmware card (A5E00228755 or compatible). The procedure walks through the use of:

• SimoCom U commissioning tool (V14.x or higher)
• 611U Toolbox V07.02.04 (toolbox_070204.exe)
• Firmware image 611u.ufw extracted from 611u_0702xx.exe (V07.02.06)
• POSMO SI/CD/CA package (posmo_070206.exe) where applicable

2. SIMODRIVE 611U Architecture and Card Identification

The 611U control unit is a two-slot module that pairs with a SIMODRIVE 611 power section. The control board contains a removable firmware memory card (CF/PCMCIA-style) carrying the executable firmware image. The full ordering structure for the 6SN1118 family is documented in the Siemens product manual for the 611 digital and universal control modules (see the Siemens Industry Online Support entry SIMODRIVE 611 digital and universal control modules with new order numbers).

For the part numbers referenced in this article:

3. Alarm E-A001: Meaning and Root Cause

Alarm E-A001 displayed at power-up indicates that the control unit cannot load a valid firmware image from the firmware card, or that the loaded image is incompatible with the hardware variant.

Common root causes:

1. Empty or corrupted firmware card — A5E00228755 was not flashed, or its content was corrupted by a previous interrupted download.
2. Cross-variant mismatch — A resolver-variant card was flashed with an encoder (NH) image, or vice versa.
3. Toolbox/SimoCom version mismatch — An attempt to load a newer firmware was aborted mid-write because the version on the firmware card is older than the minimum required by SimoCom U.
4. Stuck RS-232 download — A previous SimoCom U download was interrupted by a power loss, leaving the control unit in boot-loader mode with no valid application firmware.

4. Prerequisites

Before starting the recovery procedure, gather the following hardware and software components:

4.1 Hardware

• SIMODRIVE 611U control unit (6SN1118-0NJ01-0AA0) installed in the drive line-up, or bench-supplied through a controlled 24 V / power-section DC bus.
• Firmware card A5E00228755 (Version A) seated in the control unit.
• RS-232 null-modem cable (Siemens 6SX7005-0AB00 or equivalent) connected to a free COM port on the PG/PC.
• PG/PC running Windows XP SP3, Windows 7, or Windows 10 with a real RS-232 port. USB-to-serial adapters are not recommended for first-time recovery.

4.2 Software

5. Software Package Contents Explained

Each executable listed in section 4.2 is a self-extracting installer. Download only the components you need:

• documentation_a0703.exe — Contains the printed manual (PDF) for the 611U control and the corresponding release notes that list every bug fix from V07.01.00 onwards. Open this first to confirm that V07.02.06 resolves E-A001 for your hardware revision.
• simocomu_070206.exe — The full SimoCom U installation. After installation, the firmware download wizard is available from Start → Programs → SIMODRIVE 611U → SimoCom U → Firmware Download.
• toolbox_070204.exe — Generates 611u.ufw (control firmware) and 611u_p.ufw (power-section firmware) when the version on the firmware card is lower than the version SimoCom U is requesting.
• 611u_0702xx.exe — Self-extracting archive containing the binary 611u.ufw. Extract this on a clean FAT32 USB stick and copy the UFW to the PG/PC, do not extract directly on a Windows 7 / Windows 10 system drive because the legacy cabinet extractor occasionally corrupts filenames with long Unicode paths.
• posmo_070206.exe — Required only when commissioning POSMO SI, POSMO CD, or POSMO CA distributed servo drives on the same firmware train.

6. Step-by-Step Firmware Recovery Procedure

6.1 Pre-flight Checks

1. Verify that the control unit MLFB matches the firmware card version. 6SN1118-0NJ01-0AA0 (resolver) must use the resolver variant of the UFW image.
2. Power down the drive line-up, lock out the main contactor, and wait five minutes for the DC bus to discharge below 50 VDC.
3. Confirm the firmware card A5E00228755 is firmly seated in its slot. A partially seated card is the single most common cause of E-A001 on otherwise healthy hardware.
4. Connect the RS-232 null-modem cable between the X471 service port on the 611U and the COM1 (or COM2) port of the PG/PC.

6.2 Install SimoCom U and Toolbox

1. Run simocomu_070206.exe on the PG/PC. Accept the default install path C:\SimoComU\.
2. Run toolbox_070204.exe and install to the same root directory.
3. Restart the PG/PC and start SimoCom U. Select Online → Select Drive and confirm that the control unit responds with the current firmware version and the alarm buffer showing E-A001.

6.3 Extract the UFW Image

1. Copy 611u_0702xx.exe to a FAT32 USB stick.
2. Right-click the file on a Windows XP SP3 machine (or a Windows 7 machine booted into Safe Mode) and select Extract. The cabinet will unpack 611u.ufw, readme.txt, and a checksum file.
3. Copy the extracted 611u.ufw into C:\SimoComU\Firmware\.

6.4 Download Firmware to the Control Unit

1. Power up the drive line-up; the 611U will display E-A001 and remain in boot-loader state.
2. In SimoCom U, select Online → Firmware Download to Target System.
3. Choose the active COM port (COM1 at 19200 baud, even parity, 8 data bits, 1 stop bit is the default).
4. Browse to C:\SimoComU\Firmware\611u.ufw.
5. Click Start Download. SimoCom U will erase the firmware card, write the new image, and verify. Typical duration is 3 to 5 minutes.
6. Do not cycle power, do not close SimoCom U, and do not disconnect the RS-232 cable during the download.

6.5 Post-Download Verification

1. When the download finishes, SimoCom U reports Download OK — Please cycle 24 V on the control unit.
2. Power down the 611U, wait 10 seconds, and power up again.
3. Confirm that the seven-segment display shows 0 or the configured drive number, and that E-A001 no longer appears in the alarm buffer.
4. Re-load the project from the commissioning archive (*.par file) using SimoCom U Online → Commissioning → Download to Target.

7. Version Compatibility Matrix

8. Parameter Mapping for 6SN1118-0NJ01-0AA0

The NJ variant of the 611U uses the resolver parameters listed below. After the firmware download, verify that the commissioning values match the machine-specific backup before enabling the drive.

9. Troubleshooting Matrix

10. Field Commissioning Notes

The following field-proven tips reduce recovery time on a breakdown machine:

• Always keep a known-good firmware card in the spares cabinet. Swapping a working card is faster than a 5-minute download and immediately confirms whether the original card is electrically defective.
• Record the original resolver zero-pulse offset (P1610) and the resolver type (P1021) on the drive cover when commissioning a new machine. These two parameters are the most time-consuming to recover if the *.par archive is missing.
• Use a USB 2.0 stick formatted as FAT32 with default 32 KB allocation unit size for UFW transfers. exFAT sticks will not be recognized by SimoCom U older than V14.
• Disable Windows power management on the PG/PC before the download. Sleep or hibernation during the flash will brick the firmware card.
• After recovery, perform a controlled emergency stop test to confirm the safe-stop path is intact. The firmware download does not alter the safety wiring, but a wrongly seated card can leave the safe-torque-off (STO) path open.

11. Safety and Compliance

• Disconnect the 611U from the mains supply (line contactor open) and wait for the DC bus to discharge before touching the firmware card slot. The 611 power section maintains hazardous DC voltage for several minutes after the line is removed.
• ESD protection is mandatory. The firmware card A5E00228755 is a CMOS device and is destroyed by static discharge above 100 V. Use a grounded wrist strap when handling the card.
• The 611U must not be operated with a mismatched feedback variant. Mixing NJ (resolver) firmware with an NH (encoder) power section, or vice versa, can cause uncontrolled motion on the next enable command.

12. FAQ