Reassigning Motor Axes on SIMOTION D425 with S120 Double Motor

Overview: SINAMICS S120 Double Motor Module X1/X2 Reassignment

The SINAMICS S120 Double Motor Module with order code 6SL3120-2TE21-0AD0 is a Booksize Compact format drive that integrates two independent motor inverters into a single physical module. When paired with a SIMOTION D425-2DP/PN controller in SINAMICS Integrated topology, both motor terminals (X1 and X2) are addressed as separate drive objects (Drive 1 and Drive 2) within the same drive unit. Reassigning Motor 1 from X1 to X2 (and Motor 2 from X2 to X1) is a routine field procedure, but it requires coordinated changes to three layers:

1. Power wiring at the X1 and X2 motor terminals (U / V / W and PE).
2. DRIVE-CLiQ encoder wiring for motors that carry an integrated DRIVE-CLiQ encoder, or the corresponding SMC/SME module wiring for third-party motors.
3. SIMOTION Scout axis-to-drive assignment inside the technology object configuration so that each TO follows the new physical location.

Hardware Identification: 6SL3120-2TE21-0AD0 Specifications

Verify the actual rating by reading the nameplate on the front of the module before commissioning. The "AD0" suffix in the MLFB identifies a pre-engineered variant; the digit "1" in the rating block (2TE21) indicates the 2 × 9 A power stage. Reference: SINAMICS S120 / S150 List Manual.

SINAMICS Integrated Topology with SIMOTION D425-2DP/PN

The SIMOTION D425-2DP/PN is a motion controller with SINAMICS Integrated. The drive control software (SINAMICS S120 firmware) runs on the same hardware as the SIMOTION runtime, with the drive parameters stored under the same project. The D425 exposes drive objects (DO) directly:

• DO Drive 1 — corresponds to power stage on X1 of the Double Motor Module.
• DO Drive 2 — corresponds to power stage on X2 of the Double Motor Module.
• DO Control Unit — the SIMOTION D425 itself.
• DO Supply — the Line Module feeding the DC link.

When a technology object (TO_SpeedAxis, TO_SynchronousAxis, TO_PositioningAxis, TO_Cam) is created in Scout, it is bound to one of these drive objects through the axis wizard. The physical motor on X1 versus X2 is therefore a function of which DO the TO references, not which Scout variable name you use.

PROFINET IO and PROFIBUS DP on the D425-2DP/PN are used to connect:

• SIMATIC ET200 I/O stations
• Operator panels (SIMATIC HMI, TIA Portal)
• External SINAMICS drives (S120 CU320-2, S210, G120 with CU250S)

They do not carry the cyclic setpoint traffic for the integrated Double Motor Module. See the SIMOTION D4x5 System Manual for the topology diagram of the integrated DRIVE-CLiQ ring.

Prerequisites for the Motor Reassignment

Before opening the cabinet, confirm the following items are available and documented:

1. Project archive of the current Scout project (.zip) downloaded from the D425-2DP/PN.
2. Original commissioning printout including motor nameplate data, encoder type, and drive parameter sheet (r0001 – r3999 backup).
3. Spare DRIVE-CLiQ cables (6FX2002-series) of the correct length if re-routing is required. Maximum DRIVE-CLiQ cable length is 70 m between two nodes; 15 m is typical for cabinet-internal runs.
4. Terminal torque tool for the X1/X2 spring or screw terminals (typically 2.5 Nm for the 9 A variant).
5. PG / PC with SIMOTION Scout V4.4 SP1 or later and the matching STARTER add-in. The user must have the project offline copy and the matching firmware of the D425.
6. Valid PROFIsafe / Safety Integrated license if extended safety functions (STO, SS1, SS2, SOS, SLS) are in use. Re-mapping a motor may affect the safety slot assignment.
7. Lockout / tagout on the line infeed; verify zero potential on the DC link with a suitable meter (DC link discharge time ≤ 5 minutes for Booksize Compact).

Physical Re-wiring Procedure

1. Stop the controller, bring the machine to a safe state, and inhibit all axes from the HMI or via the user program.
2. Open the Line Module contactor and verify the DC link is discharged (status LED off on Double Motor Module).
3. Label each motor cable at both ends (motor housing and module terminal) before disconnecting. Use heat-shrink labels or numbered cable markers. Capture which DRIVE-CLiQ port on the module each motor encoder occupies.
4. Disconnect Motor 1 power from terminal X1 (U1, V1, W1, PE, brake +/– if present). Do not disconnect Motor 2.
5. Disconnect Motor 2 power from terminal X2 (U2, V2, W2, PE, brake +/– if present).
6. Disconnect the DRIVE-CLiQ connectors from the module face (or from the SMC/SME modules if third-party encoders are used). Note which port belonged to which motor.
7. Reconnect Motor 1 power to terminal X2 (using the same phase sequence U/V/W — direction is set by parameter p1820, not by cable order). Torque to 2.5 Nm.
8. Reconnect Motor 2 power to terminal X1.
9. Reconnect the DRIVE-CLiQ cables in the same logical order — what matters for the topology is which motor encoder is plugged into which port.
10. Reconnect shields to the module grounding bar with the supplied clamp. Maximum shield loop area ≤ 40 mm² to comply with EMC directive for SINAMICS Booksize.
11. Close the cabinet, restore the line contactor, and observe the module LEDs. After DC link ramp-up, the RDY LED should turn green within 5 seconds.

DRIVE-CLiQ Topology Considerations

DRIVE-CLiQ enforces a strict ring topology. Each node has two ports (port 0 / port 1), and the system watches the ring for break detection via the topology comparison (p9906, p9907, p9908). When you swap motors at X1 / X2 but keep the same physical DRIVE-CLiQ cables plugged into the same ports, the topology is unchanged and Scout will not raise a topology error.

If you also physically move the encoder cables to follow the motors, the topology will detect a swap. The controller compares the live topology to the commissioned topology; if the components move between ports, fault F01340 (Topology: Component moved) is raised. Clear it by either:

• Accepting the new topology with "Accept topology change from PG/PC" in STARTER / Scout, or
• Manually swapping the drive assignment (p120[0] ↔ p120[1] alias mapping) so the Scout axis that was bound to DO Drive 1 now binds to DO Drive 2.

For details, refer to SINAMICS S120 List Manual — fault and alarm chapter.

SIMOTION Scout Software Reconfiguration

The Scout project owns the binding between technology objects (TOs) and drive objects (DOs). The motor swap has to be reflected in this binding.

1. Open the project offline in SIMOTION Scout. Connect online to the D425-2DP/PN in "Download project to target" mode only after the offline edits compile cleanly.
2. Inspect the project tree under Axes > Drive 1 and Axes > Drive 2. Each TO references a drive (e.g. Drive_1, Drive_2) plus a configured encoder (encoder_1, encoder_2).
3. Open Axis 1 configuration and navigate to the Drive assignment page. Note the current drive selection (likely Drive_1).
4. Open Axis 2 configuration and note the current drive selection (likely Drive_2).
5. Swap the references:
   • Set Axis 1 drive assignment to Drive_2.
   • Set Axis 2 drive assignment to Drive_1.
6. Swap the encoder references in the same axis configuration dialog so that encoder_2 follows Axis 1 and encoder_1 follows Axis 2.
7. Save the project, compile, and correct any axis names referenced from the user program (the _getAxisNumber() or symbolic names like Axis_Motor1).
8. Search and replace in the MCC charts and ST sources for any direct references to Axis_Motor1, Axis_Motor2, or the underlying TO_ID. The TO_ID is assigned at compile time and will change if you rename the TO.
9. Re-compile the project. Resolve any "Axis not assigned" warnings.
10. Download to the target with the controller in STOP state. Restart the SIMOTION runtime.

Commissioning and Verification

1. Power up the line module and confirm the DC link reaches nominal 600 V DC within the configured ramp time.
2. Check drive object status on Scout: r0002 for Drive 1 and Drive 2 should show "Operation enabled (r0899 = 1)" after the controller run-up.
3. Verify encoder direction: With each axis released and a small jog command, the position actual value (r0483 or the TO's actual position field) must increment in the expected sense. If negative, swap p0410 bit 1 for that drive or invert the motor cable phase sequence (only one of the two — never both).
4. Verify axis-to-motor binding: From Scout's axis control panel, issue a small velocity setpoint to Axis 1. Physically observe Motor 2 (which is now on X1) spinning, and vice versa. This is the quickest sanity check that the software swap matches the physical swap.
5. Check the holding brake on each motor if equipped (parameter p1215). The brake is released through DO output; confirm the brake release timing is correct after the swap.
6. Run the safety acceptance test if SS1, SLS, or STO is configured. The Safety Integrated slot on the D425-2DP/PN expects a logical-to-physical axis mapping that may need to be re-acknowledged.
7. Archive the modified project via Project > Archive in Scout and store on a backup medium (SIMATIC memory card, USB, or TIA Portal project server).

Troubleshooting Matrix

Field-Proven Notes and Edge Cases

• Identical motors: If the two motors are the same type with the same encoder, the parameter set is interchangeable and no drive re-commissioning is required — only the Scout binding changes.
• Heterogeneous motors: If the motors differ in rated power, rated current, encoder resolution, or winding inductance, copy the source drive parameter set onto the target drive object in STARTER before issuing any motion commands. Otherwise current controller instability (F07802) is likely.
• Third-party motors without DRIVE-CLiQ: Use an SMC20 (incremental sin/cos) or SME25 (EnDat 2.1) Sensor Module. The DRIVE-CLiQ topology will show the SMC/SME as a node, and swapping them physically requires the same topology acceptance step.
• Safety Integrated extended functions: The safety slot number is bound to the DO, not the TO. After the swap, the safety view in Scout will show the SLS limits for Drive_2 now supervising the motor on X1. Re-run the acceptance test.
• Hot-plug vs. cold-plug: Booksize Compact modules are not hot-pluggable in this configuration. Only the Line Module and Motor Modules of the S120 family support DRIVE-CLiQ hot-plug during operation; the Double Motor Module is a peripheral slot.
• Mechanical direction check: After the swap, jog each axis with a small velocity. The direction of motion must match the program's expectation. If reversed, fix it in software (encoder invert bit) rather than re-wiring the motor — this avoids disturbing the EMC-compliant shield termination.
• Brake release: When the holding brake cable is moved with the motor, the brake release is still commanded by the drive object that owns the new axis. Confirm p1215 (motor holding brake configuration) was migrated to the new drive.
• Commissioning data retention: Save the parameter set to the SIMATIC memory card via p0977 = 1 after the swap so a cold restart reloads the new binding.

Related Siemens Documentation

• SIMOTION D4x5 System Manual — Topology, interfaces, SINAMICS Integrated configuration.
• SINAMICS S120 / S150 List Manual — Parameter list, fault and alarm reference, DRIVE-CLiQ rules.
• SINAMICS S120 Commissioning Manual — Motor data identification, encoder commissioning, brake setup.