Replacing CU320 with CU320-2 DP: Motor Module and F1650 Procedure

Overview: Migrating SINAMICS S120 from CU320 to CU320-2 DP

The SINAMICS S120 drive platform has transitioned its central Control Unit from the original CU320 (MLFB 6SL3040-0MA00-0AA0) to the higher-performance CU320-2 DP (MLFB 6SL3040-1MA00-0AA0, PROFIBUS variant) and CU320-2 PN (MLFB 6SL3040-1MA01-0AA0, PROFINET variant). This migration is common in retrofit programs for material-handling equipment such as RTG (Rubber Tyred Gantry) cranes, where legacy drive cabinets must be modernized without replacing the complete line-up.

The mechanical and DRIVE-CLiQ topology of the new CU320-2 is similar, but the firmware, parameter set, and the connected Motor Modules/Sensor Modules must be verified. Some early Motor Modules and Sensor Modules use CIB (Control Interface Board) assemblies that are not electrically compatible with the CU320-2 firmware. The most commonly reported field problem on RTG retrofits is the Motor Module 6SL3320-1TE33-8AA0 (75 kW / 400 V, booksize-format) which is incompatible with the CU320-2 when its MLFB ends in ...-8AA0 and must be replaced by a build with MLFB ending >=3 (for example 6SL3320-1TE33-8AA3 or later).

This reference consolidates the compatibility rules, the F1650 acceptance test, the SMC30 sensor module status, the CIB/CIM migration question, and the STARTER commissioning flow. It is written for field engineers executing the cabinet swap and the subsequent commissioning.

Hardware Comparison: CU320 vs CU320-2 DP

The CU320 and CU320-2 are not pin-compatible at the backplane level. Although the booksize Control Unit slot is identical, the CU320-2 is a re-engineered module with a more powerful MPC8247/8282-class controller, expanded memory, and updated DRIVE-CLiQ routing. The following table summarizes the key engineering differences.

For an RTG retrofit the fieldbus choice is dictated by the PLC: most RTGs use SIMATIC S7-300/S7-400 with PROFIBUS, so the CU320-2 DP variant is the direct replacement. If the crane is being re-cabled to PROFINET, the PN variant (6SL3040-1MA01-0AA0) is the drop-in equivalent.

Motor Module Compatibility — MLFB 6SL3320-1TE33-8AA0

The Motor Module flagged in the field is the booksize 75 kW / 400 V unit with MLFB 6SL3320-1TE33-8AA0. Siemens categorically states that this part is not compatible with the CU320-2 and the matching CU320-2 firmware. The unit must be replaced with a build that has the MLFB ending greater than or equal to 3 (i.e. 6SL3320-1TE33-8AA3 or higher).

Why the cut-off? The early Motor Modules used a CIB (Control Interface Board) that routed the DRIVE-CLiQ and 24 V power differently, and the gate-driver firmware revision was tied to the CU320 firmware generation. When a CU320-2 brings up the line-up, it interrogates the Motor Module's electronic rating plate (read via DRIVE-CLiQ) and checks the firmware compatibility table. A Motor Module ending in -8AA0 reports an incompatible version and either remains in start-up inhibit or generates an F1650-class fault on first commissioning.

For an RTG retrofit budget, the practical impact is that at least one booksize Motor Module must be procured as new for every line-up. Drive line-ups on an RTG commonly contain: hoist, trolley, and gantry Motor Modules. Verify each Motor Module's rating plate before pulling the CU320. A safe procurement pattern is to replace all three (or four, if the crane has a separate slewing drive) Motor Modules with units from the same build batch to keep the spare-parts inventory uniform.

Sensor Module SMC30 Compatibility

The SMC30 Sensor Module (MLFB 6SL3055-0AA00-5CAx) decodes HTL/TTL encoders on the motor side and is part of the standard S120 line-up. The SMC30 is fully compatible with the CU320-2 — it can be retained in the retrofit as long as its firmware is updated to a CU320-2-compatible release (typically V4.4 or later, depending on the CU320-2 firmware). The same applies to SMC10 and SMC20. The only required step is to re-insert the SMC30 in the STARTER topology, accept the new electronic rating plate, and load the parameter set.

For an RTG encoder retrofit, where the hoist is fitted with an HTL encoder fed by the crane's slip-ring assembly, the SMC30 is the standard Sensor Module and it does not need to be replaced.

CIB vs CIM: Can the Motor Module Be Upgraded by a Board Swap?

The question that frequently arises during a retrofit is whether a Motor Module's CIB (Control Interface Board, the older generation) can be replaced with a CIM (Control Interface Module, the newer generation) to make an -8AA0 Motor Module CU320-2-compatible. The short answer, based on Siemens' official guidance, is: do not perform this swap in the field.

The reasons are practical:

• The CIB is soldered into the Motor Module's gate-driver stage; the connector pin-out, current-sense resistor values, and gate-driver timing are different between CIB and CIM generations. A field swap voids the type-test certification.
• The CIM requires a different gate-driver firmware loader, and the calibration data stored on the CIB's EEPROM cannot be transferred to the CIM by board swap — the Motor Module's IGBT characteristics have to be re-gauged at the factory.
• Siemens Service explicitly treats the Motor Module as a service part: a CIB-equipped unit is returned to a service center for a CIB-to-CIM exchange, or scrapped in favour of a new module.

Therefore, the field-recommended action is to purchase a new Motor Module with the appropriate MLFB ending (>=3). The 6SL3320-1TE33-8AA3 is a direct slot-in replacement and is electrically and mechanically identical to the -8AA0 from the line-side and motor-side terminals.

Fault F1650 — Acceptance Test Status

Fault F1650 is raised by the SINAMICS S120 firmware when the drive detects that a mandatory acceptance test has not been executed or has been invalidated by a parameter change. On the S120 platform, the most common F1650 triggers are:

For a CU320 to CU320-2 migration in an RTG, F1650 typically appears in the power-stack acceptance sub-condition because the Motor Module was physically replaced. The drive will not release the enable signals until the acceptance test is performed and signed off.

Acceptance Test Procedure for F1650

1. Open the SINAMICS S120 project in STARTER (V5.x or higher, matching the CU320-2 firmware).
2. Go online with the drive. Confirm that the CU320-2, the new Motor Module, and the SMC30 are all in RUN state with green RDY LED.
3. In the navigation tree, right-click the drive (e.g. Drive_1 → Hoist) and choose Commissioning → Safety Integrated → Acceptance test. If the Safety Integrated functions are not in use (e.g. STO via terminal only, no SS1/SLS), the acceptance path used is the power-stack acceptance under Commissioning → Power unit → Acceptance test.
4. STARTER will step through a wizard. For each axis, confirm the following acceptance points:
   • Motor type and motor code match the rating plate on the new Motor Module.
   • DRIVE-CLiQ wiring order matches the topology view (no port swaps).
   • Encoder assignment and direction are correct (use p0410 = 1 to read the encoder, then run a short test move in jog mode p1120 / p1121).
   • Current limit and torque limit are within the RTG hoisting envelope (e.g. hoist current limit p0640 ≤ Motor Module rated current).
5. When the wizard reports Acceptance test successful, STARTER writes the test signature to r3926 (acceptance test status) and clears F1650. Save the project to the PG/PC and then RAM → ROM the CU320-2 CompactFlash card.
6. Re-energise the line-up and verify that F1650 is no longer in the fault buffer. Use the operator panel or r0947[0..63] to inspect the buffer.
7. Document the acceptance test in the crane's safety file. The signature r3926.0 = 1 is mandatory evidence for the crane safety log book.

Commissioning Flow: CU320-2 DP on an RTG

The following step-by-step procedure assumes the original CU320 is removed, the new CU320-2 DP is inserted, and the Motor Modules have been upgraded to MLFB ending >=3.

Prerequisites

• STARTER V5.1 SP3 or higher installed on the PG/PC. (For CU320-2 firmware V5.2 or higher, Startdrive V15.1 or TIA Portal V16 can be used as alternatives.)
• The CU320-2 CompactFlash card with the matching firmware version (typically V4.7 SPx or V5.2, depending on the STARTER version used for the original project).
• Original STARTER project backup, taken from the CU320 before the swap.
• PROFIBUS DP master address configured and matched between the PLC and the CU320-2 (default 7, changeable via p0918).
• All DRIVE-CLiQ cables re-seated. Use only Siemens DRIVE-CLiQ cables; aftermarket cables frequently cause intermittent faults that are difficult to diagnose.

Step-by-Step Commissioning

1. Insert the CompactFlash card with the original project's firmware in the CU320-2 slot. Power up the cabinet. The CU320-2 will boot, read the rating plates of the connected Motor Modules and Sensor Modules, and build a new topology.
2. Open STARTER and load the original CU320 project. The project will be detected as incompatible with the new CU320-2 hardware. Follow the wizard — this is the exact workflow shown in SIOS 90277154.
3. Accept the device change from CU320 to CU320-2 DP. STARTER migrates the parameter set, adjusting parameter numbers that have been re-organized in the new firmware (e.g. p1070 remains the same, but several safety parameters have moved to a new p96xx range).
4. Re-insert the new Motor Module in the topology view. Drop it into the same DRIVE-CLiQ port that the original used. If the topology does not auto-detect, manually set the Motor Module's component number (p0121, p0131).
5. Re-insert the SMC30 in the topology view. If the encoder interface was on the same SMC30 in the old line-up, no further parameter work is needed. If the encoder was moved to a different SMC port, rewire physically and re-assign in STARTER (p0400, p0420).
6. Go online — load the project to the drive. STARTER will report mismatches. Resolve each mismatch by clicking ‘Accept’. The most common mismatch is the firmware version of the SMC30. Allow STARTER to upgrade the SMC30 firmware (this takes about 60–90 s per SMC30).
7. Run the automatic motor identification. With the motor uncoupled (or in no-load condition), issue p1910 = 1 and p1960 = 1 for the rotating identification. The drive will inject test pulses, calculate the motor equivalent circuit, and write the results to p1910 = 0.
8. Run the encoder test. Issue p1990 = 1 to start the encoder test. STARTER will prompt to rotate the motor by a few degrees and then accept the encoder direction.
9. Execute the F1650 acceptance test per the procedure described above.
10. Save to ROM. In STARTER, click Copy RAM to ROM to commit all parameters to the CU320-2 CompactFlash card.
11. Functional test with the PLC. Run the hoist, trolley, and gantry axes in manual mode, then in automatic, and verify that the PROFIBUS DP cyclic data exchange is healthy. Use the PLC's diagnostic buffer (STEP 7 → PLC → Diagnostic buffer) to confirm no diagnostic interrupts.
12. Update the crane's electrical documentation with the new MLFBs, firmware versions, and acceptance test date.

DRIVE-CLiQ Topology and Parameter Migration

The DRIVE-CLiQ ring structure of the original line-up must be preserved. On the CU320-2 the four ports (X100 — X103) behave identically to the CU320, but the port-to-port auto-routing has been improved; if a Motor Module is detected on the wrong port, STARTER will offer a ‘swap ports’ action that re-writes the topology table without physical re-cabling.

Common parameters that engineers must hand-migrate (because the wizard does not always preserve them):

For hoist applications on RTGs, the load-holding brake control via p1215 (configuration) and p1216 (opening time) must be re-validated because the new Motor Module has a different gate-driver timing. A hoist that drops the load by a few centimetres at start is a typical symptom of a brake that was not re-commissioned.

Calculating Hoist Current Limit for RTG Sizing

When upgrading the Motor Module, the line current and apparent power for the booksize 75 kW unit can be confirmed using:

• Three-phase apparent power: kVA = sqrt(3) × V_LL × I_line / 1000
• Single-phase apparent power: kVA = V × I / 1000

For the 6SL3320-1TE33-8AA0/-8AA3 Motor Module:

• Rated output current I_n = 145 A (3-phase) at 400 V
• Maximum output current I_max = 217.5 A (1.5 × I_n)
• Apparent input power: kVA = sqrt(3) × 400 × 145 / 1000 ≈ 100 kVA (three-phase line)

Use these as the basis for the crane's transformer sizing and the line filter (e.g. Line Filter 6SL3000-0BE33-1AA0) check. If the RTG line filter is retained from the original CU320 line-up, it is electrically identical and re-usable.

Troubleshooting Matrix

Parameter Set Backup and Roll-Back

Before the swap, dump the CU320 parameter set to a PG/PC file using STARTER's Load to PG/PC action, and copy the CompactFlash card image to a folder on the PG/PC. This guarantees a roll-back path: if the new CU320-2 cannot be commissioned within the maintenance window, the original CU320 can be re-inserted and the line-up returned to service. The CompactFlash card from the original CU320 is not readable in the CU320-2 and vice-versa, so the two must be kept strictly segregated.

Field-Proven Caveats and Lessons Learned

• Some early RTG cabinets (built 2005–2010) used a CU320 with a SINUMERIK integrated firmware variant. Confirm the firmware project name in the CU320 CompactFlash before assuming the project is a standard SINAMICS S120. If it is a SINUMERIK-related variant, the CU320-2 cannot directly replace it — the entire line-up must be re-engineered.
• The DRIVE-CLiQ cables inside the cabinet have a 50,000-cycle insertion rating. Re-inserting old cables into new DRIVE-CLiQ sockets wears the gold plating. For high-vibration RTG cabinets, replace all DRIVE-CLiQ cables as part of the retrofit.
• The CU320-2 requires the CUA31 or CUA32 adapter for the older S120 line modules (e.g. SLM 6SL3130-6AE15-0AAx). On RTG retrofits where the original SLM is retained, do not forget to add the CUA32 to the line-up; otherwise the SLM will not appear in the topology.
• If the RTG is fitted with a SIMOTION D4x5 controller and the SINAMICS is in integrated mode (SINAMICS firmware loaded into SIMOTION), the migration is more involved and the CU320-2 is a longer lead-time item. Confirm the controller type before booking the spare part.
• Always re-commission the SINAMICS Safety Integrated functions after the Motor Module swap. The Motor Module's internal gate-driver timing affects the safe-torque-off (STO) response time, and the original p9650/p9850 values may exceed the SIL 3 budget with the new Motor Module.

Document the Migration

After successful commissioning, update the crane's safety file with the new CU320-2 DP MLFB, the new Motor Module MLFB, the SMC30 firmware version, the F1650 acceptance signature (r3926), and the commissioning engineer's name. The documentation is the primary evidence for the next annual crane survey and is what the inspector reads when verifying the drive's safety integrity. Keep a printed copy inside the crane's documentation cabinet; electronic-only records can be lost during a tropical rainstorm in port operations.

FAQ