Resolving SINAMICS S210 Servo Drive Screaming Noise During

1. Problem Description

A SINAMICS S210 servo drive system installed in a delta robot application exhibits loud, high-frequency screaming or squealing noise during jogging, manual move commands, and automated motion profiles. The audible noise presents as a sustained high-pitched tone that is clearly distinguishable from normal motor commutation sound. The phenomenon appears intermittently and is reproducible during low-speed jog operations, manual MOVE_JOG axis commands issued from the SIMATIC S7-1511T Technology CPU, and during One Button Tuning (OBT) execution itself.

2. Affected System Configuration

The reported fault topology consists of the following Siemens components:

• Servo drive: SINAMICS S210 (PROFINET variant, 6SL3xxx series)
• Servo motor: SIMOTICS S-1FK2 (high-dynamic, planetary gearbox coupled)
• Controller: SIMATIC S7-1511T (Technology CPU with motion control firmware V2.x or later)
• Communication: PROFINET IRT, 1 ms position controller cycle, 250 µs current controller cycle
• Communication telegram: Standard Telegram 105 (PZD-5/9 with Dynamic Servo Control)
• Mechanical load: Delta robot parallel linkage (three-axis parallel kinematic structure)

Refer to the SINAMICS S210 Servo Drive System Operating Instructions for the canonical hardware configuration matrix, wiring diagrams, and commissioning checklist applicable to the S210 + 1FK2 combination.

3. Root Cause Analysis

Audible high-frequency noise from a SINAMICS S210 drive is the acoustic signature of velocity-loop instability. In servo systems, the velocity controller (typically a PI structure with the bandwidth set by proportional gain p and integral action time n) regulates motor speed against the load. When the controller bandwidth exceeds the mechanical resonance frequency of the load, or when the integral component accumulates error at a rate that exceeds the system's ability to dissipate it, the loop self-oscillates. The oscillation frequency often falls within the audible band (2 kHz to 16 kHz), producing the reported "screaming" characteristic.

3.1 One Button Tuning Behavior

Siemens One Button Tuning (OBT) is an automatic commissioning routine that drives the motor through a sequence of motion profiles and identifies the moment of inertia, friction, and optimal speed/current controller gains. The S210 firmware offers multiple OBT dynamic-response levels:

When OBT is executed in Conservative mode on a parallel kinematic structure such as a delta robot, the routine's internal mechanical-model assumption (rigid, single-axis coupling) does not match the actual load. The identified moment of inertia is therefore incorrect, and the resulting PI gains are too high for the actual coupled system. The factory default in OBT Conservative mode enables torque pre-control (feedforward), which compounds the issue by injecting a torque command proportional to the desired acceleration profile. If the identified inertia is wrong, the feedforward torque is wrong, and the feedback loop must work harder to correct the error — producing oscillation.

3.2 Torque Pre-Control (P5271.4)

Parameter p5271 in the S210 parameter list configures the speed controller's torque pre-control (feedforward) behavior. The relevant bit assignments are documented in the S210 List Manual (LHM) and are summarized as follows:

In OBT Conservative mode, Bit 4 is set to YES by default. This means the drive engages torque pre-control automatically when the OBT routine completes. For highly compliant or non-linear mechanical loads — such as the carbon-fiber or aluminum arms of a delta robot — the pre-control torque computed from the OBT-identified inertia is inaccurate, and the resulting disturbance appears as audible oscillation.

3.3 Communication Cycle and Telegram 105

Telegram 105 is the standard Siemens PROFIdrive telegram for high-performance servo applications. It supports Dynamic Servo Control (DSC), where the position controller runs on the SIMATIC S7-1500T CPU and the velocity controller runs on the SINAMICS drive, with the position error sent as a velocity feedforward to the drive on each PROFINET IRT cycle. The telegram structure for Telegram 105 is:

The 1 ms PROFINET IRT cycle is the default for S7-1500T motion control. Telegram 105 is the correct choice for delta-robot kinematics because it provides DSC, offloading position-loop computation to the Technology CPU where the inverse-kinematics transformation is already executed. Telegram selection itself does not cause the noise, but it does affect how aggressively the velocity controller must respond to position errors propagated through the linkage.

4. Diagnostic Procedure

Before applying the resolution, confirm the noise origin with the following sequence:

1. Capture the noise: Record an audio/video clip of the noise during a jog command. Compare the pitch to known mechanical frequencies (gearbox mesh, bearing race, encoder ring).
2. Read fault and warning buffers: In Startdrive (TIA Portal V16+) or SINAMICS Startdrive V15.1, connect online to the S210 and read r0945 (fault code) and r2122 (alarm code). The presence of F07900 (motor overspeed) or A07910 (drive overtemperature) indicates active protection intervention but is downstream of the noise.
3. Trace the velocity loop: Use the S210 trace function to record n_set (speed setpoint), n_act (actual speed), and M_set (torque setpoint) at the controller cycle rate. Audible noise correlates with high-frequency oscillation visible in the trace between n_set and n_act.
4. Check OBT log: Review p5271 and the OBT result parameters. Note whether torque pre-control (Bit 4) is active.
5. Inspect mechanical coupling: Verify that the motor-to-linkage coupling is rigid and free of backlash. Delta robot parallel arms transmit reaction forces back to the motor; any compliance amplifies controller instability.

5. Resolution

Two complementary solutions resolve the issue. Solution A is preferred when the OBT results are otherwise acceptable; Solution B is the definitive recovery path when OBT results are unreliable for the mechanical system.

5.1 Solution A — Disable Torque Pre-Control

Retain the OBT-identified PI gains but switch off torque feedforward. This eliminates the inaccurate feedforward component while preserving the controller bandwidth that OBT found.

1. Connect Startdrive online to the affected S210.
2. Navigate to Parameters → Speed controller filter or enter p5271 in the parameter search.
3. Read the current value of p5271. Confirm Bit 4 is 1 (torque pre-control active).
4. Open the bit editor for p5271 and set Bit 4 to 0 (NO).
5. Click Set (RAM), then Copy RAM to ROM to persist the change.
6. Perform a controlled jog of the affected axis. Confirm the noise is eliminated and that following error remains within the configured tolerance.
7. Save the project to the TIA Portal project and download to the S7-1511T.

5.2 Solution B — Factory Reset and Manual Re-Commissioning

This is the path verified by the field report. A factory reset clears all OBT results, all user parameter changes, and all fault memory, returning the drive to its Siemens-default tuning.

1. Bring the machine to a safe state. Disable all motion enable signals.
2. Open Startdrive, connect online to the affected S210.
3. Navigate to Online & Diagnostics → Commissioning → Reset to factory settings.
4. Select All parameters (not just the safety parameters) and confirm the reset.
5. Wait for the drive to complete the reset cycle. The drive may reboot; PROFINET connection will be re-established automatically.
6. Re-run the basic commissioning: motor code, encoder type, direction of rotation, and PROFINET device name from the TIA Portal project.
7. Do not execute One Button Tuning at this stage. Commission with the default Siemens speed-controller parameters (p1460 = Kp, p1462 = Tn) shipped from the factory.
8. Verify the jog command with the default tuning. The noise should be absent.
9. Save and download the project.

The default speed-controller gains are conservative and tuned for the standard 1FK2 motor with a rigid coupling. For a delta robot, these defaults are typically acceptable because the controller bandwidth is well below the first resonance of the parallel linkage. This sacrifices dynamic performance relative to OBT, but produces stable, silent operation.

5.3 Solution C — Manual Tuning of OBT Results

If the application requires higher dynamic performance than the factory defaults can deliver, manually tune the OBT-identified values downward:

1. Record the OBT results: p1460 (speed controller Kp) and p1462 (Tn).
2. Reduce p1460 by 30% to 50%.
3. Increase p1462 by 30% to 50% (lower integral action).
4. Disable p5271.4 (torque pre-control).
5. Jog the axis and verify.
6. Iterate: if the axis response is too soft, increase p1460 in 10% steps until the noise returns, then back off 20%.

6. Verification Checklist

After applying any of the solutions above, confirm the resolution with the following checks:

7. Telegram 105 Configuration Notes

Although Telegram 105 was not the root cause in this incident, the configuration must be reviewed to ensure DSC is functioning. In the TIA Portal device configuration for the S210:

1. Open Device view → S210 → Properties → PROFINET interface → Telegram configuration.
2. Confirm the telegram is set to Standard Telegram 105 on slot 1 of the drive.
3. Verify the Isochronous mode checkbox is enabled, with the application cycle set to the Motion Control cycle of the S7-1511T (typically 1 ms).
4. Confirm that DSC is enabled in the Encoder configuration of the TO (Technology Object) on the PLC side. Without DSC, the position controller runs on the drive with a higher cycle time, which can mask velocity-loop instability and complicate diagnosis.

8. Preventive Measures for Delta Robot Applications

Delta robots present a uniquely challenging load for servo tuning because of the parallel-linkage mechanical coupling. The following practices reduce the probability of recurring noise events:

1. Avoid OBT Conservative mode as a starting point. The conservative preset in S210 firmware does not account for parallel-linkage inertia variation over the workspace. If OBT must be used, select Dynamic mode and immediately verify with the trace function before commissioning.
2. Disable torque pre-control by default for delta robots. Set p5271.4 = 0 regardless of OBT mode. The variable inertia over the workspace makes feedforward torque unreliable.
3. Use a position-controller cycle of 1 ms. This is the S7-1500T default and is mandatory for delta-robot kinematics; longer cycles reduce DSC effectiveness.
4. Mechanical verification first. Confirm that the three arms of the delta robot are balanced, the bearings are preloaded, and the encoder coupling is rigid before commissioning the controller. Many "tuning problems" are actually mechanical problems.
5. Document the working PID values. Once stable operation is achieved with the default tuning or manually tuned values, record p1460, p1462, and p5271 in the TIA Portal project documentation.
6. Use the S210 trace function during commissioning. Real-time traces of n_set, n_act, and M_set expose oscillation that is invisible in the standard commissioning screens.

9. Firmware and Version Considerations

Parameter layout, default values, and OBT algorithm behavior vary between SINAMICS S210 firmware versions. Confirm the firmware level of the affected drive via parameter r0018 before applying the resolutions above:

Refer to the SINAMICS S210 Operating Instructions for the firmware-specific parameter list and the S210 List Manual (LHM) on the Siemens Industry Online Support portal for the complete parameter documentation.

10. Escalation Path

If the noise persists after applying Solutions A, B, and C in sequence:

1. Open a Siemens Industry Online Support request with the drive's serial number, firmware version (r0018), motor article number, and the trace recordings.
2. Attach the TIA Portal project (zipped, with the user blocks redacted if confidential).
3. Include a video of the noise event with the audio track intact.
4. Reference this knowledge-base scenario in the request to expedite triage.

Siemens technical support typically escalates such cases to the SINAMICS application engineering team, who can review the OBT identification data and recommend application-specific PI tuning or filter settings (notch filters on the velocity loop are a common next step for parallel-linkage loads).