SINAMICS DCM DCC Chart Won't Open in STARTER Root Cause

1. Problem Description

A SINAMICS DCM (or SINAMICS S120) drive unit equipped with a DCC (Drive Control Chart) extension is commissioned from a PC running STARTER over PROFIBUS through a CP5711 USB adapter. The connection is established, accessible nodes are found, and the drive unit is accepted into a freshly created STARTER project. The drive is uploaded to the engineering PC twice - once with the "Overwrite available DCC libraries" option ticked and once without - yet double-clicking the DCC chart in the project tree produces the error "DCC chart cannot be opened" or "No DCC source data available." The DCC option license is installed in the drive, the chart is clearly present in STARTER, but the editor refuses to display the function blocks.

This is one of the most common data-loss scenarios in SINAMICS field service: the drive is operational, the chart is running, but the engineering source is unrecoverable from the unit alone.

2. Root Cause: Source Data Was Never Archived to the Drive

DCC charts consist of two physically separate data objects on the Control Unit's non-volatile memory (CF card):

• Compiled runtime code (DCC runtime data, executable chart): Written to the drive every time a DCC chart is downloaded. This is the data the drive executes in real time.
• Engineering source (DCC source / chart description): Written only when the user explicitly enables the download options "Store additional data in the file system" and "including DCC Chart data" in STARTER before pressing Load to target system.

If the source-data options are not selected at the moment of the original download, the runtime chart is stored, but the source (.dcb / chart description) is never written to the file system of the Control Unit. A subsequent Upload to PG brings back the runtime block, but STARTER has no editable source to open - hence the message "DCC chart cannot be opened / modified." The chart can be monitored, but not edited, exported, or reverse-engineered.

3. DCC Chart Data Storage Architecture

SINAMICS stores DCC information in two distinct partitions on the CF card of the Control Unit (e.g. CU320, CU320-2, CU310, CX32, CUD on the DCM). Understanding this layout is essential for any service intervention.

The user file system path is typically /user/sinamics/data/dcc/ and is visible to STARTER through Project Navigator > Drive unit > Commissioning > Additional data. When this directory is empty after an upload, the source cannot be reconstructed.

4. Mandatory Pre-Download Options

Before any project download that includes a DCC chart, the user must explicitly enable the following options in the STARTER Load to target system dialog:

1. Open the project in STARTER.
2. Right-click the drive unit and select Target system > Load > Load CPU/drive unit to target system.
3. In the dialog that appears, click Options / Additional settings.
4. Tick "Store additional data in the file system" (= "Zusätzliche Daten im Dateisystem ablegen").
5. Tick "including DCC Chart data" (= "inklusive DCC-Chart-Daten").
6. Confirm with OK and execute the load.
7. After the load completes, perform a Copy RAM to ROM (p0977 = 1) to commit the user file system to non-volatile memory.

5. Recovery Procedure - Step by Step

The recovery path depends on whether the original engineering project (with the DCC source) is still available somewhere on the engineering network or backups.

5.1 Scenario A: Original Project Is Available

1. Open the original STARTER project that was used for the original commissioning.
2. Establish PROFIBUS / PROFINET connection to the SINAMICS drive unit.
3. Perform Target system > Load > Upload to PG with the "Overwrite DCC libraries" option disabled so the original DCC source on the PG is preserved.
4. The DCC chart can now be opened, edited, and re-downloaded with the extra-data options enabled.
5. After successful load, run Copy RAM to ROM so the user file system is committed to the CF card.

5.2 Scenario B: Original Project Is Lost, Drive Is Still Present

1. Create a new STARTER project and connect online to the drive.
2. Upload the drive unit to the PG. The chart is brought back as a runtime-only object.
3. Open the chart in monitoring mode: STARTER will display a warning that source data is missing. Monitoring still works, but editing is blocked.
4. Conclusion: The chart can be reverse-engineered only by re-creating it from the function manual, the parameter list, and the online monitoring of the runtime instance. This is rarely practical for complex DCC logic.

5.3 Scenario C: Drive Must Be Replaced (Hardware Swap, Power Upgrade)

1. Read out the actual DCC chart by enabling online monitoring in the existing project (even without source).
2. Export the parameter set of the drive to a file (Target system > Export parameters).
3. Document the DCC topology by going online and capturing the input/output wiring of every DCC block from the project navigator.
4. Replace the hardware (Motor Module, CU, or DCM unit).
5. Open the original project, change the topology to the new hardware (e.g. p0201 = r0200 to accept the new power rating), and download with the extra-data options enabled.
6. Perform Copy RAM to ROM.

6. Factory Reset Procedure for SINAMICS S120 (CU320-2)

When swapping a Motor Module for one of a different power rating, the Control Unit must be told to accept the new component. The standard factory-reset sequence from the SINAMICS S120 List Manual is shown below. Every step is performed in the expert parameter list, in the order shown.

After step 7, the CU reboots and the new Motor Module is accepted. The DCC runtime chart, if present in the CU, is not overwritten by this procedure - it lives in the user file system, not in the parameter image.

7. RAM-to-ROM and DCC Preservation

Two parameters trigger a non-volatile save on SINAMICS drives, and engineers often confuse them.

8. Replacement Scenario: New Motor Module With Higher Power (x2)

The user case describes replacing a SINAMICS S120 Booksize Motor Module with one of double the rated power. The correct sequence is:

1. Save the DCC chart source before the swap (see Section 4 - either from the original project, or by re-downloading with extra-data options to a known-good CU).
2. Power down the drive, swap the Motor Module, leave the CU in place.
3. Power up. The CU will detect the new power unit and report a topology error.
4. Apply the factory-reset sequence from Section 6 to accept the new power code (p0201 = r0200).
5. Open the project containing the DCC source. Adjust the Motor Module part number if necessary, then perform a complete project download with both extra-data options enabled (Section 4).
6. Execute Copy RAM to ROM in STARTER, which is equivalent to p0977 = 1.
7. Verify the DCC chart opens from the project tree without warnings.

If step 1 is skipped, the chart can no longer be opened in STARTER after the swap, because the source is not on the CU and the new Motor Module brings no source with it.

9. Verification and Diagnostic Checks

After applying the recovery procedure, run the following checks to confirm the chart is fully recoverable.

1. Chart opens without error: Double-click the DCC node in the project tree. The chart editor must open, not display a "cannot open" dialog.
2. Source files present on the CU: In STARTER, go to Target system > Target system information > User file system. The path /user/sinamics/data/dcc/ must contain the chart description files (typically *.dcb and a sub-folder per chart).
3. Libraries are resolved: Open the chart. None of the blocks should display a red "unresolved block type" marker. If unresolved blocks are present, the DCC library has to be re-installed via Options > DCC libraries.
4. Online / offline compare: Target system > Compare. The result must show "identical" for the DCC chart, the libraries, and the parameters.
5. RAM-to-ROM state: Read r3996 (BOOT state) - it must report 0 (no pending save) and r0977 must equal the boot state. If r0977 = 1 and the drive reboots, the file system is in flux; wait until idle.

10. Common Pitfalls

11. Preventive Measures for the Engineering Workflow

• Add a "DCC extra-data options enabled" item to the commissioning checklist of every drive with a DCC chart.
• Archive the complete STARTER project (including *.dcc, *.dcb, library references, and the user file system) in the customer's version-controlled engineering repository after every change.
• Run a weekly automated backup of the CU's user file system to a network share using STARTER's scripting interface or the SIMATIC Automation Tool.
• Document the DCC chart with a topology drawing and a parameter cross-reference so that, in case of a complete source loss, the chart can at least be partially reconstructed from the documentation.
• When upgrading hardware, always export the parameter set (Target system > Export parameters) and the user file system (Target system > Save to file system) before powering down.

12. Frequently Asked Questions