Problem Overview
When commissioning or replacing a Siemens SINAMICS drive system, engineers frequently encounter a firmware version mismatch between the CU320 control unit installed in the cabinet and the project tree configured in the STARTER commissioning tool. A common field scenario is a replacement CU320 (order number 6SL3040-0MA00-0AA1) shipped from the warehouse with hardware version B and a downlevel firmware load (typically the V2.1.x line), while the existing project was built against an earlier CU320 of the same part number but hardware version G running firmware V2.6.2. STARTER refuses the download and the drive cannot be brought online.
This reference documents the root cause, identifies the three viable recovery paths, and provides a field-proven commissioning procedure that preserves the project and minimizes downtime. The material applies to the original CU320 control unit (6SL3040-0MA00-0AA1) used in SINAMICS S120, SINAMICS G130, and SINAMICS G150 cabinet systems, and references the device manuals available on the Siemens Industry Online Support portal. The hardware revision letter on the type plate (for example, hardware version G or hardware version B) reflects the PCB revision only; the loaded firmware is determined entirely by the contents of the CF card.
Affected Hardware and Part Numbers
Confirm the exact MLFB (order number) and hardware version (release letter) printed on the type plate of the control unit before applying any of the recovery paths described later in this document. The mismatch is most often reported on the part numbers listed below.
| Component | Order Number (MLFB) | Notes |
|---|---|---|
| CU320 control unit (original) | 6SL3040-0MA00-0AA1 | Legacy CU320; used in SINAMICS S120, G130, G150; firmware on CF card |
| CU320-2 control unit (PROFIBUS) | 6SL3040-1MA01-0AA0 | Successor to CU320; same footprint, higher performance; see Siemens product announcement |
| CU320-2 control unit (PROFINET) | 6SL3040-1MA02-0AA0 | Variant with PROFINET interface; firmware on CF card |
| CF card (empty, 1 GB) | 6SL3054-0AA00-1FA0 | Card without firmware; user loads the image via STARTER or the Web server |
| CF card (with firmware, license-bound) | Consult Siemens support for current MLFB | Card pre-imaged with current S120 / G130 / G150 firmware; license coupled to cabinet serial number |
| SINAMICS G150 cabinet unit | 6SL3710-1GE35-0AA0-Z | Air-cooled cabinet drive; firmware is G130/G150 specific and not interchangeable with S120 |
For the G150 drive on order number 6SL3710-1GE35-0AA0-Z, the control unit and CF card are physically the same as the S120 build, but the firmware image and license file are G150-specific and are not interchangeable with the standard S120 firmware load. This is the key reason a generic S120 firmware file pulled from the Siemens public support page will not bring a G130 or G150 online. The trailing -Z on the MLFB designates option codes that must be quoted in full when reordering a firmware card.
Root Cause: Firmware, CF Card, and STARTER Compatibility
The CU320 has no internal non-volatile storage for the device firmware. At every power-up, the boot loader reads the firmware image from the CF card inserted in the front-panel slot, validates the signature, and loads it into RAM. If the card is missing, blank, or contains an image that does not match the connected drive line-up, the control unit either halts at the boot menu or comes up with the firmware reported as "Version 0.0.0" in STARTER.
The most common failure mode is therefore not a defective CU320 at all. It is a difference in the contents of the CF card that shipped with the new unit versus the one in service before the swap. The two most frequent reasons for a download failure from a STARTER project built for a different firmware are:
- The new unit ships with a downlevel firmware image (for example, V2.1.x) on its card, while the project in STARTER references V2.6.2. STARTER compares the device firmware reported online with the project firmware and refuses to download when the major version differs.
- The project is offline and a Download to target system is attempted without first opening the correct offline project that matches the firmware on the new card. STARTER displays the message "The firmware version of the target device does not match the offline project" and aborts.
STARTER enforces two compatibility checks at the moment the user clicks Download to target system:
- Online/offline firmware match. The firmware version stamped into the offline project tree (visible at Drive → CU → Properties → Version) must equal the version reported by the online target. A mismatch triggers the "Firmware version differs" error and blocks the download.
- Project / device consistency. STARTER also checks the DO (drive object) topology and the connected components. A wrong SINAMICS type (S120, G130, G150) in the offline project against an online G150 line-up will fail with "Device configuration does not match".
Both checks can be overridden only by an explicit firmware load to the CF card followed by a power cycle. Once the firmware on the card matches the offline project, the project downloads cleanly. The two steps - load firmware to the card, then download the project - are the backbone of every recovery path.
The CU320 front panel exposes two status LEDs that give the first hint of the failure mode:
- RDY (Ready). Green steady = OK; green flashing = boot; orange steady = warning; red steady = fault (typically card read error or missing firmware). See the SINAMICS S120 Control Units and Additional System Components manual for the full blink-code table.
- COM (Communication). Yellow = PROFIBUS / PROFINET activity; off = no host connection or wrong address.
Recovery Path A: Direct CF Card Transfer (S120, G130, G150)
The cleanest path when the original control unit is still available and functional is to move its CF card into the replacement unit. The replacement unit then boots with the exact firmware image, project file, and license that the old unit was running. This is the recommended Siemens field practice.
- Power down the SINAMICS line-up and wait for the DC link to discharge. Verify the charge LED on the line filter or Active Line Module is OFF before opening any cabinet door.
- On the original CU320, open the front cover and eject the CF card from the front-panel slot. Press the eject button beside the slot; do not pull on the card itself.
- Insert the ejected card into the replacement CU320 in the same orientation. The card is keyed.
- Power the line-up back up. The CU320 boots the firmware from the card and STARTER should report the expected firmware version online.
- Connect STARTER to the line-up, go online, and perform "Load to target system" only if the project has been edited offline. If the original project is still on the engineering PC, the existing online connection resumes without further action.
Recovery Path B: Firmware Update for S120 (No Original Card Available)
If the original CU320 is damaged and its CF card cannot be recovered, the firmware for an S120 line-up can be reloaded to the card manually using STARTER. The S120 firmware image and the STARTER commissioning tool are both available as public downloads on the Siemens support portal.
- Insert the new (empty or downlevel) CF card into the replacement CU320 and power the unit once to confirm the boot loader can read the card.
- Power down and remove the card. Insert the card into a PC equipped with a CF card reader. The card must be readable as a removable drive.
- Copy the contents of the S120 firmware package to the root of the card. The image is delivered as a ZIP archive containing the directories
FW2.6.2(or the matching version),USER, and the license files. - Reinsert the card into the CU320, power the line-up, and verify the firmware version reported in STARTER matches the version in the project tree.
- Go online in STARTER and run "Download to target system" to push the project onto the drive.
Alternatively, the firmware can be loaded directly through STARTER without removing the card:
- Go online with the CU320 in STARTER.
- Right-click the drive in the project tree and select "Load firmware to CF card" (or use Target system → Load firmware to CF card, depending on STARTER version).
- Select the matching firmware package on the local hard drive.
- STARTER writes the image to the card and prompts for a power cycle. Perform the cycle and re-go online.
For a step-by-step reference, see the SINAMICS S120 Control Units and Additional System Components manual on the Siemens support portal.
Recovery Path C: G130 / G150 Firmware Procurement (Vendor Only)
The G130 and G150 firmware is not published on the Siemens public support page. Siemens restricts the G150 firmware image to authorized service channels because the license file and cabinet options are tightly coupled to the serial number of the line-up. If the original CF card is lost or unreadable, the only legitimate procurement path is:
- Record the MLFB of the G150 cabinet (for example, 6SL3710-1GE35-0AA0-Z), the serial number on the type plate, and the full -Z option list.
- Contact the local Siemens sales representative or the regional Siemens Service department. Provide the MLFB, serial number, and the firmware version that must be reloaded.
- Siemens issues a service ticket and supplies a CF card pre-imaged with the correct G150 firmware and license, matched to the serial number of the line-up.
- Insert the card, power the line-up, verify the firmware version in STARTER, and download the project.
Cabinet Topology and Recovery Decision Tree
The diagram below shows the physical placement of the CU320 in a typical SINAMICS S120 / G150 line-up and the location of the CF card that holds the firmware.
The flowchart below codifies the decision logic for selecting the correct recovery path before opening the cabinet.
Step-by-Step Commissioning Procedure
The following procedure ties together the three recovery paths into a single, deterministic commissioning flow that works on S120, G130, and G150 line-ups.
- Verify safety state. Open the cabinet door only after the DC link has discharged. Confirm the line filter or Active Line Module charge LED is OFF and the cabinet ground is bonded. Lock out the main breaker per site EHS rules.
- Identify the hardware. Photograph the type plate of the CU320 and any active line or motor module. Record the MLFB, hardware release letter, and serial number into the commissioning log.
- Identify the firmware. With the cabinet powered, read the firmware version in STARTER: Target system → Device diagnostics → Version. Note both the CU firmware version and the version of every drive object in the line-up.
- Match the project. Open the project on the engineering PC and compare the offline firmware version with the online version. If they match, go directly to Load to target system. If they do not, follow Path A, B, or C to align the firmware before downloading.
- Load the project. With the firmware aligned, click Download to target system in STARTER. Acknowledge the safety prompts. STARTER writes the parameters to the drive and synchronizes the DO topology.
- Copy RAM to ROM. After the download, right-click the drive and select "Copy RAM to ROM" (which drives parameter p0971) to commit the parameters to the non-volatile area of the CF card. This step is critical: a power cycle without copying RAM to ROM loses any parameter changes.
- Power cycle the line-up. Power the cabinet off, wait for the DC link to discharge, and power back on. Verify that the CU320 reboots into the expected firmware version and that STARTER reconnects without errors.
- Run a no-load identification. For S120 and G150 line-ups with motor modules, perform a motor data identification at standstill (p1910) and, where supported, a rotating measurement (p1960). The identification locks the motor model into the project and prevents nuisance overcurrent trips on the first motion command.
Verification and Acceptance Test
After commissioning, run a structured acceptance test before releasing the drive to production. The test list below is the minimum required for an S120 / G150 retrofit.
| Step | Check | Expected Result |
|---|---|---|
| 1 | STARTER online connection | Online mode green, all DOs visible |
| 2 | CU firmware version | Matches the offline project version exactly |
| 3 | Drive object topology | All line-up components detected; no DOs in fault state |
| 4 | Parameter backup | Copy RAM to ROM completed without error |
| 5 | Power cycle test | Drive boots to ready state without operator intervention |
| 6 | Motor ID | p1910 and p1960 completed; motor model stored |
| 7 | Reference value test | Drive follows a small setpoint (for example 5%) in motor-potentiometer mode |
| 8 | Safety functions | STO and SS1 tested per the safety acceptance plan |
| 9 | Alarm log | No active warnings or faults in the diagnostic buffer |
| 10 | Project backup | STARTER project archive saved to the engineering server |
Key SINAMICS Parameters and Common Fault Codes
The parameter table below lists the most common CU320 / drive parameters touched during the recovery procedure. Always verify against the SINAMICS parameter documentation in the support portal for the specific firmware release in use.
| Parameter | Function | Used In |
|---|---|---|
| p0009 | Device commissioning parameter filter | Set to 0 to complete commissioning, 1 for quick commissioning |
| p0010 | Commissioning parameter filter | Set to 0 to enable parameter changes, 1 for quick commissioning |
| p0970 | Reset all parameters to factory | Use p0970 = 1 to reset drive, = 5 for safety reset |
| p0971 | Save parameters to non-volatile memory | Set p0971 = 1 to commit RAM to ROM (the "Copy RAM to ROM" function) |
| p1910 | Motor data identification at standstill | Set p1910 = 1 to run standstill ID after motor data entry |
| p1960 | Speed controller optimization (rotating) | Set p1960 = 1 for rotating measurement with no load |
| p0304 / p0305 / p0307 | Motor rated voltage / current / power | Enter nameplate values before p1910 |
The fault table below lists the SINAMICS alarms that most often appear when a CF card mismatch is the underlying cause. The full fault database is in the SINAMICS S120 List Manual on the Siemens support portal.
| Code | Meaning | Typical Cause | Action |
|---|---|---|---|
| F01000 | Internal software error | Firmware corruption on CF card | Re-image the CF card from the STARTER firmware package |
| F01015 | Internal communication error | DRIVE-CLiQ topology mismatch | Re-check DRIVE-CLiQ wiring and DO assignment |
| F01031 | Sign-of-life error from CU | CF card boot failure or blank card | Re-image the CF card, verify the card type |
| F08501 | PROFINET connection error | Wrong addressing or cable fault | Check address switches and connector |
| F30001 | Power unit overcurrent | Motor ID skipped or wrong motor data | Run p1910; verify p0304 / p0305 / p0307 |
| F30002 | DC link overvoltage | Line-side fault or regen limit | Verify line filter and Active Line Module status |
| F30004 | Inverter heat sink overtemperature | Cooling fan fault or blocked intake | Inspect fans; clean the heat sink |
| F30011 | Line phase failure | Mains phase missing or blown fuse | Check the upstream fuse and phase rotation |
Troubleshooting Matrix
The matrix below covers the failure modes most often reported after a CU320 replacement. Each row lists the symptom in STARTER, the most likely cause, and the corrective action.
| Symptom in STARTER | Likely Cause | Corrective Action |
|---|---|---|
| "Firmware version of the target device does not match the offline project" | CF card on the new CU320 carries a downlevel firmware image | Move the original CF card to the new unit, or load the matching firmware via STARTER |
| "Device configuration does not match the offline project" | S120 firmware loaded onto a G150 line-up, or vice versa | Replace the CF card with the cabinet-specific firmware image from Siemens Service |
| "License missing" or "License check failed" | License card not transferred with the firmware card | Move the license card; if lost, request a replacement from Siemens Service |
| CU320 boots, RDY LED steady red | CF card unreadable, corrupted, or empty | Re-image the card from the STARTER firmware package, or replace the card |
| CU320 boots, RDY LED blinks slowly, COM LED off | PROFIBUS or PROFINET address conflict or cable fault | Check the address switches on the CU320; verify the cable and connector |
| Drive goes online but downloads abort with "Access denied" | Access level too low; STARTER not in Expert mode | Set the access level to Expert in STARTER, re-enter the drive password if assigned |
| Project downloads, but a power cycle loses the parameters | Copy RAM to ROM was skipped | Go online and execute p0971 = 1; power cycle again to confirm persistence |
| Motor turns the wrong direction on the first run | Encoder direction or phase sequence inverted | Invert p0410 for encoders, or swap two motor phases; record the change in the project |
| Drive trips with F30001 on first enable | Motor data not entered or motor ID not run | Enter p0304 / p0305 / p0307 and run p1910 |
Spare-Part Strategy and Migration to CU320-2
Most firmware-mismatch incidents on a CU320 swap are preventable with a disciplined spare-part strategy. Three practices consistently eliminate the failure mode in production sites:
- Pre-image spare CU320s. When a spare CU320 enters the warehouse, image its CF card with the current production firmware version (for example, the same V2.6.2 the running line-up uses). Label the card with the firmware version and the date. The spare can then be deployed without an additional firmware load in front of the cabinet.
- Maintain a STARTER version on the engineering PC that matches the project. If the active production line runs V2.6.2, the engineering PC should run a current STARTER release with the matching SINAMICS support package, and the project should be archived in the engineering server with the support package locked. Mixing STARTER versions across engineering stations is the most common source of cross-version project corruption.
- Document the -Z option list of every G150 cabinet. When a G150 firmware card is requested from Siemens Service, the engineer must have the MLFB, serial number, and the full -Z option code list ready. Maintaining this list in the asset management system eliminates a service-call delay of several days.
For long-term planning, consider migrating the legacy CU320 (6SL3040-0MA00-0AA1) to the current SINAMICS CU320-2 control unit. The CU320-2 offers a higher digital-input count, additional PROFIBUS and PROFINET variants, and ongoing firmware support. The migration is a board swap inside the same footprint; the existing CF card is not reusable and the project must be re-commissioned in the current STARTER release. Consult the SINAMICS S120 Control Units and Additional System Components manual for the migration checklist before quoting the swap.
Frequently Asked Questions
Why does STARTER refuse to download a project to a replacement CU320 even though the part number matches?
The CU320 carries the firmware on its CF card, not in internal memory. A spare unit can ship with a different firmware image than the project on the engineering PC, and STARTER blocks the download on version mismatch. Move the original CF card or load the matching firmware to the card before downloading the project.
Can the same firmware file be used for a SINAMICS S120 and a SINAMICS G150?
No. The S120 firmware is a public download on the Siemens support portal; the G130/G150 firmware is cabinet-specific and bound to the serial number of the line-up. Loading S120 firmware on a G150 results in a topology error and the drive will not enter run. Order a pre-imaged card from Siemens Service for any G130 or G150 retrofit.
What is the difference between the CU320 (6SL3040-0MA00-0AA1) and the CU320-2 (6SL3040-1MA0x-0AA0)?
The CU320-2 is the successor to the original CU320. It uses the same footprint, offers more digital inputs, and supports both PROFIBUS (6SL3040-1MA01-0AA0) and PROFINET (6SL3040-1MA02-0AA0) variants. The CF card and project format are not directly interchangeable; the project must be rebuilt in the current STARTER release and a new CF card must be ordered.
How do I copy parameters to non-volatile storage so they survive a power cycle?
After every project download, right-click the drive in STARTER and select "Copy RAM to ROM". This sets parameter p0971 = 1 and writes the volatile parameters to the CF card. Without this step, any parameter change made in STARTER is lost on the next power cycle.
Where can I download the SINAMICS S120 control-unit firmware and the STARTER commissioning tool?
Both packages are published on the Siemens Industry Online Support portal. The firmware is delivered as a ZIP archive that is extracted to the root of the CF card; STARTER is a Windows installer that must be paired with the SINAMICS support package matching the project. For G130/G150 firmware, contact your local Siemens Service department; these images are not on the public portal.