Resolving SIMOTION D445-1 F1910 Profibus Setpoint Timeout Errors

1. Problem Summary

A SIMOTION D445-1 motion controller paired with a SINAMICS S120 (CU320) drive line starts the machine, runs for roughly 30 seconds, then drops with:

• F1910 — PROFIBUS: Setpoint timeout on the SINAMICS S120
• F1912 — Sign-of-life failure in clock-synchronous operation on the SINAMICS S120
• The D445-1 transitions to STOP operating mode

The two S120 faults are not independent. F1912 is the isochronous bus sign-of-life counter mechanism detecting a missing PROFIdrive telegram. F1910 is the supervisory message indicating that valid process data (PZD) has stopped arriving. Both faults are typically a downstream symptom of the SIMOTION D445-1 going to STOP, losing its connection to the drive, or having a broken isochronous PROFIBUS link.

2. Affected Hardware and Firmware

Check the active firmware of both devices in SCOUT online (Target system > Accessible nodes > Device diagnostics). Mismatched firmware between D445-1 and CU320, especially around the PROFIdrive V3/V4 conformance level, has historically caused intermittent sign-of-life faults after controller restarts.

3. Error Code Definitions and Decoding

F1910 — PROFIBUS Setpoint Timeout

Parameter reference: r2050[0..15] (PZD receive words) and the time defined in p2040 (PROFIBUS monitoring time) and p2042 (PROFIdrive PZD mapping). When no new setpoint telegram arrives within the configured monitor window, S120 raises F1910 with default reaction OFF2 (fast ramp to zero, pulse inhibit).

F1912 — Sign-of-Life Failure, Clock-Synchronous

S120 expects the SIMOTION master to set the four-bit sign-of-life counter (STW1 bits 12–15) in the PZD telegram. The counter must increment by 1 in every isochronous cycle Tdp. Two consecutive failures → F1912 with default reaction OFF3.

Both faults are visible in the S120 alarm history and are mirrored into the SIMOTION technology object alarm buffer when configured.

4. Architecture: How the D445-1 Talks to the S120

The D445-1 acts as PROFIBUS DP master (or PROFINET IO controller on newer variants). The S120 CU320 is configured as a DP slave on isochronous slot. The relevant PROFIdrive telegrams for axis control on a D445-1 typically are:

The D445-1 must be configured in isochronous (equidistant) mode for the axis to operate. The isochronous cycle time Tdp must match the SIMOTION IPO/Servo synchronization (e.g., Tdp = 1 ms, Tmapc = 2 ms, Servo_fast = 1 ms). Mismatched Tdp between controller and drive is a common cause of F1912.

5. Root Cause Analysis Matrix

6. Diagnostic Procedure (Step-by-Step)

1. Go online to the D445-1 in SCOUT. Right-click the SIMOTION device → Connect to target system. Use the SIMOTION Ethernet or PROFIBUS interface.
2. Open the Diagnostic Buffer. Right-click the SIMOTION device → Diagnostics → Diagnostic Buffer (or Target system → Diagnostic Buffer).
3. Read timestamps in chronological order. The buffer shows operating state transitions, system events, application events, and incoming S120 alarms forwarded through the device. Compare the timestamp of the STOP transition against the timestamp of F1910/F1912.
4. Identify the stop trigger. Common entries:
   • Operating mode transition RUN → STOP (reason: Task watchdog) — MotionTask or BackgroundTask overran.
   • STOP (reason: Configuration error) — project / topology fault, axis or TO failure.
   • STOP (reason: Technology object alarm) — encoder fault, axis state error.
   • STOP (reason: User program) — explicit _stop() call or STW write.
5. Inspect the Technology Object alarms. Right-click the affected axis (e.g., Kettbaum_7) → Alarm history. Encoder faults, drive faults, and follow-up errors are stored here.
6. Check the topology. In SCOUT open the project navigator → D445-1 → Topology. The DRIVE-CLiQ port view shows the physical components. Any red or yellow node indicates a fault or missing part. If Motor 7 / its Sensor Module is physically absent or its encoder is faulty, the topology still expects it.
7. Cross-check with the S120 alarm history. Open the online S120 device → Diagnostics → Alarms. Note the order: drive faults first, then SIMOTION STOP, or vice versa. This is the most reliable evidence of which event triggered the chain.

7. Topology Verification and Axis Deactivation

If a motor or its encoder is faulty (as with Kettbaum_7 in the field case), the SIMOTION project can be configured to either keep the axis in the topology with a suppressed fault or remove it. The two approaches behave differently.

Option A — Deactivate Axis in Topology (Online Suppression)

1. Open HW Config → D445-1 → Topology.
2. Locate the affected component (e.g., Motor Module at port DRIVE-CLiQ 3 or the Sensor Module for the encoder).
3. Set the component to disabled / not active.
4. Download the topology to the D445-1.
5. Deactivate the technology object in the project: Axis → Properties → Deactivate.

Option B — Remove Axis Completely from Project

1. Delete the technology object for the axis from the project.
2. Remove all references from MotionTasks, programs, and interlocks.
3. Remove the corresponding drive object from the S120 topology (online) or from the project.
4. Compile and download the entire project.

8. MotionTask Revert Procedure

If the error appeared immediately after a MotionTask program change:

1. Open the project and locate the modified MotionTask (Tasks → MotionTask_x → Programs).
2. Compare the current assignment against the previously running version (use version control, archive, or SCOUT project history).
3. Verify:
   • Task priority and execution level (IPO, IPO2, Servo, Servo_fast).
   • Watchdog time (_waitForCondition loops, _checkTaskTime).
   • Calls to _stop(), _stopEmergency(), or _disableAxis() introduced by mistake.
4. Restore the previous source code, recompile, download to D445-1, perform a full restart.

Even when the new project was already reverted to the previously working version, the D445-1 may still hold a residual state if the download or restart was incomplete. Always perform a full project download followed by an MRES (memory reset) of the D445-1 to clear residual alarms:

• SCOUT: Target system → Memory reset → confirm → power-cycle the D445-1.
• Alternative: Use the SIMOTION IT web server (http://<IP>/simotion) to issue a controlled restart.

9. STOP Mode Investigation on D445-1

The D445-1 is more sensitive to STOP transitions than older SIMOTION D425/D435 variants. A STOP during operation is typically caused by:

10. Resolution Procedure (Sequential)

1. Connect online to the D445-1 in SCOUT and capture the current diagnostic buffer.
2. Identify the earliest event in the fault chain (STOP, topology error, task watchdog, or TO alarm).
3. Resolve the root event first; do not chase F1910/F1912 directly.
4. Verify topology: DRIVE-CLiQ wiring, all components present and active. For Kettbaum_7: either repair the encoder/Sensor Module or fully remove the axis from project and topology.
5. Check isochronous configuration: SCOUT → PROFINET/PROFIBUS → properties of the S120 slave → Isochronous mode. Confirm Tdp, Ti, To match the S120 parameter p978[0..2] and the SIMOTION Servo task.
6. Restore the MotionTask program to the previously working version. Compile and download.
7. Full project download + MRES of the D445-1.
8. Power cycle the S120 line (Active Line Module, then Motor Modules).
9. Go online and clear all pending S120 faults via Drive → Acknowledge.
10. Run the machine for several minutes without the modified axis and verify no F1910/F1912 reappear.

11. Verification Checklist

12. Field-Commissioning Notes

• Always perform a full project download after any change to the topology. Partial downloads leave residual technology objects that can re-trigger F1910/F1912 after a warm restart.
• Avoid mixing SCOUT versions across engineering stations. A project saved in SCOUT V5.4 opened in V5.1 can cause inconsistent task timing that manifests as a sign-of-life failure only on the first restart.
• Document the S120 firmware on the project cover sheet. S120 V4.x to V5.x changes the default PROFIdrive conformance and the sign-of-life tolerance behavior.
• Keep MRES as the last resort: it clears all retentive data, axis homing positions, and recipe data.
• For PROFINET variants of the D445-1, the same F1910/F1912 behaviour is raised on PROFINET IO failure; the diagnostic path is the same, but the watchdog timing is governed by SendClock and ReductionRatio in PROFINET instead of Tdp in PROFIBUS.

13. Related Faults and Documents

When F1910/F1912 is observed, check for the following related codes that often appear in the same alarm burst:

• F08501 — PROFINET/PROFIBUS sign-of-life error on the PROFINET IO controller side.
• F07412 — Drive-side encoder fault (often the root cause when an axis is left in topology with a broken encoder).
• F30003 — Undervoltage on the S120 DC link after OFF2, typical follow-up of a forced stop.
• C08502 — Warning: life-sign failure, pre-alarm before F1912.

Refer to the official Siemens documentation for parameter and fault references:

• SIMOTION D445-1 Operating Instructions
• SIMOTION SCOUT TIA Configuration Manual
• SINAMICS S120 List Manual (F1910, F1912 references)
• SIMOTION Diagnostic Functions and Alarms Manual
• PROFIdrive Profile Drive Technology (PNO)

14. FAQ