SIMOTION D425 Not Ready: Resolving F364 B284 and F01912 Faults

1. Symptom Summary

A SIMOTION D425 controller reports a persistent red "Ready" LED after the machine was running in production. The user program stops executing and the seven-segment display on the CU320-2 / integrated front panel shows a steady "6" with a flashing decimal point. The SIMOTION diagnostic buffer logs event ID 16#F364:B284, a PROFIBUS Integrated alarm class entry. Online with the SINAMICS Integrated drive object the system reports a 30xxx-class ground / I²t fault, the SIMOTION runtime eventually drops into STOP with event 16#F360:BE06 (missing TaskExecutionFaultTask) and 16#F360:BF8D (floating-point exception in user program at line 0x21). On the first manual motion command after recovery, SINAMICS raises F01912 — sign-of-life failure for PROFIBUS clock-synchronous operation — and, in later sequences, F01910.

This article documents the field procedure used to recover the unit: connect to the SINAMICS Integrated over a routed online connection, isolate the failing power module, replace it, re-identify the DRIVE-CLiQ topology, restore the SINAMICS parameters (p10, p640, p948), reload the SIMOTION user program, and clear the F01912 / F01910 bus cycle fault. The procedure applies to SIMOTION D425 DP (6AU1425-0A...0AA0) and D425 PN (6AU1425-1A...0AA0), control unit firmware V4.3 / V4.4 / V4.5, with SCOUT 4.3.1 / 4.4 / 4.4 SP1 / 4.5 or TIA Portal V14 SP1 / V15 / V15.1 with the SIMOTION HSP (HSP0303 / HSP0304).

2. Hardware Architecture: SIMOTION D425 and SINAMICS Integrated

The SIMOTION D425 combines a SIMOTION runtime with a SINAMICS S120 drive line-up on a single SIMOTION D4x5-2 DP/PN control unit. The integrated drive objects run on the same CU320-2 and are accessed internally via PROFIBUS Integrated (D4x5 DP) or PROFINET Integrated (D4x5-2 PN). Key catalog numbers that you will encounter during the recovery:

Two PROFIBUS segments coexist on the D425 DP: the external DP master interface (X136) and the internal PROFIBUS Integrated bus that links SIMOTION to SINAMICS Integrated. Both share the same PROFIBUS chip but use different subnet IDs in HW Config. Loss of the internal bus sign-of-life is what later triggers F01912; loss of the external bus drives X136-specific alarms. DRIVE-CLiQ ports (X200–X203 on a Motor Module, X100–X103 on a CU320-2) carry deterministic point-to-point traffic at 100 Mbit/s and run isochronously with the SIMOTION Tmapc. Cable length changes of more than 0.5 m without a topology re-acknowledge are a frequent cause of residual F01912 because the propagation delay shifts.

Reference documentation: SIMOTION D4x5-2 Manual (109750209) and SINAMICS S120 Commissioning Manual (109757263).

3. Decoding the Front-Panel Indicators

The CX32 / CU320-2 integrated display uses a single-digit seven-segment plus a status LED pair. The patterns encountered on the failing system are:

The "Ready" LED turning solid red corresponds to SINAMICS status "Commissioning / fault present", which the SIMOTION runtime also reflects in the system variable driveStates.actualState showing FAULT or STARTUP_LOCKED. The diagnostic buffer event 16#F364:B284 belongs to the PROFIBUS Integrated alarm class. The 0xB284 sub-code maps to "DP integrated bus, sign-of-life counter not equal to 1" — the PROFIBUS Integrated telegram is missing a master sign-of-life, which is consistent with the SINAMICS Integrated sitting in a faulted state that prevents it from answering correctly. It is a symptom of the underlying drive problem, not the root cause.

4. Diagnostic Buffer and Event ID Interpretation

Open the SIMOTION diagnostic buffer via SCOUT / TIA Portal: right-click the D425 → "Target system" → "Connect to target system" → "Diagnostics" → "Diagnostic buffer". Translate the 16# IDs using the SIMOTION System Functions and Error Messages List (109757178) and the SINAMICS S120/S150 List Manual (109757265). Two complementary event streams are encountered in this failure mode:

Pay attention to the timestamp on the diagnostic buffer entries. If the buffer shows year 1994 and the system clock reads 2016, the SIMOTION has lost its real-time clock — the CR2032 battery is dead or the CF card was re-initialised. The faults themselves are still valid; only the time stamp is wrong. Replace the CR2032 buffer battery on the D4x5-2 (3.0 V Li, Siemens part A5E00236943) and reload the time via the time-of-day synchronisation interface (HMI time-of-day, NTP over Ethernet, or SCOUT "Set time on target").

5. Root Cause Analysis: Ground Fault and I²t

The 30xxx-class alarm originates in the power module. Two scenarios are common on a "suddenly" failing machine:

1. Motor insulation breakdown. Megger the phase-to-phase and phase-to-PE insulation of the motor at 500 V. A healthy insulation reads > 100 MΩ. Anything < 1 MΩ is a hard short and points at the cable, the connector, or the motor windings. Check the DRIVE-CLiQ motor encoder cable as well — a shorted SMC/SME/SMI 24 V feed to the resolver windings will produce F30011 and a red Ready LED even if the power module is healthy.
2. I²t trip on a stuck axis. Mechanical binding (a ballscrew jam, a bearing seizing, a coupling slip) drives the IGBT current up. The I²t model of the new power module — 9 A instead of the original 5 A — is sized for the larger motor, so any pre-existing mechanical problem becomes more visible as a current warning rather than a fault. The 5 A module masked it; the 9 A unit cannot.

In the present case the cabling tested clean and the motor was healthy, isolating the failure to the 5 A Smart Line / Motor Module itself. Replacing the module cured the 30xxx alarm, but the F01912 surface fault remained because the new module had not been integrated into the DRIVE-CLiQ topology and the SIMOTION project did not have its original SINAMICS parameters loaded.

6. Drive Replacement Procedure and DRIVE-CLiQ Topology Recognition

The SINAMICS S120 line-up is a topology-driven system. Each DRIVE-CLiQ port (X200–X203 on a Motor Module, X100–X103 on a CU320-2) has a fixed expected neighbour; the system raises F01315 / F01317 if a neighbour is missing or has a different catalog number than the stored topology. After swapping a 5 A module for a 9 A module you must re-record the topology. Field-procedure:

1. De-energise the line voltage, wait 5 minutes for DC-link discharge, verify with a Cat III 600 V meter on the DC bus terminals (DCP / DCN at the Smart / Active Line Module).
2. Replace the Motor Module. Use an identical DRIVE-CLiQ cable length; mismatched lengths are a frequent cause of F01912 because the propagation delay shifts.
3. Power up. The CU320-2 will detect the new module and raise F01315 ("Topology comparison").
4. In SCOUT / TIA Portal, navigate to the SINAMICS Integrated drive unit → "Topology" → "Commissioning" → "Acknowledge topology change" (equivalent to p9904 = 1, p9905 = 1 from Starter; SCOUT exposes it as a button on the topology editor).
5. With the new module selected, run "Identify" so that p0101 / p0107 / p0108 / p0110 / p0111 / p0112 / p0114 / p0115 are read from the electronic rating plate stored in the DRIVE-CLiQ interface (DQI). This is the "automatic commissioning" that p948 = 3 invokes.
6. Perform "RAM → ROM" (p0977 = 1) so the topology is saved to the CF card. Repeat for the CU if you changed the catalog variant (p0977 = 1 on the control unit object as well).
7. Drive warm restart: p0972 = 1 (parameter reset to factory then reload from non-volatile), or p0009 = 0 and p0972 = 0 for a soft restart that retains the new parameters.

DRIVE-CLiQ rules that affect this procedure: maximum 16 nodes per line, maximum 8 nodes in series, maximum 100 m of total cable per line, max 8 m between nodes, max 5 m on the secondary port of an Active Line Module. DQI is a one-time read at startup; if you want to re-read it (for example, after a re-flash) you must re-issue p948 = 3 or p9910 = 1 ("Save DQI").

7. Parameter Recovery: p10, p640, p948

The three parameters that almost always need attention after a drive replacement are p10, p640, and p948. In this case, all three had to be re-issued in sequence:

Procedure executed in the present case:

1. p948 = 3 → automatic drive identification (DQI read, parameters re-scaled).
2. p640 manually adjusted to match the 9 A module's thermal model (otherwise the I²t alarm persists).
3. p10 = 0 to leave the commissioning state.
4. p0977 = 1 to write parameters to ROM (this writes to the SINAMICS backup file on the CF card as well).
5. p10 of the CU_003 (control unit) was changed from 30 (factory) to 0 (ready) because the new module had been factory-reset and the CU still expected the old parameters.

From the SCOUT HMI the equivalent dialog is "Online → Drive unit → Commissioning → Quick commissioning", which exposes p10, p640, p948, p0977 in a wizard form. Always accept at the end of the wizard with the "Save RAM to ROM" button.

8. Program Reload and STOP Cause Investigation

Once the SINAMICS side is healthy, the SIMOTION runtime may still be in STOP because the program on the CF card was overwritten during the rescue procedure, or because the project on the PG was older than the running one. The two STOP-related events are:

• 16#F360:BE06 — "STOP caused by missing TaskExecutionFaultTask". Every project should contain a TaskExecutionFaultTask that the runtime calls when a MotionTask or BackgroundTask raises an exception. Its absence causes SIMOTION to drop into STOP for safety.
• 16#F360:BF8D — "Floating-Point exception in user program". The diagnostic detail names the MCC / ST source file (gstnst, line 0x21) and the system error 11130. A divide-by-zero, a denormalised float, a corrupted input cast, or a 32-bit register overflow when the project is recompiled with a newer compiler can cause this.

Recovery actions:

1. Upload the project from the CF card backup (or, if no backup exists, request the original program from the machine builder). The SIMOTION D425 stores both the runtime project (SIMOTION.DAT, SIMOTION.IDX) and the drive backup under \USER\SIMOTION on the CF. SCOUT target system → "Load to PG" / "Copy RAM to ROM" retrieves the active project.
2. If the card is blank, format it on the SIMOTION D-CFU tool, then load the project via SCOUT: target system → "Load to target system" → "Load to target device" (SCOUT 4.3.1 / 4.4 / 4.4 SP1 / 4.5, or TIA Portal V14 SP1 / V15 / V15.1 with HSP0303 / HSP0304). Always select "Download with transfer" so the project and the technology packages (TPcam, TPaxis, TPtemp) land on the card.
3. Recompile the project to regenerate the FPU exception site. The line 0x21 in gstnst is a stable bookmark in MCC; double-click the message in the diagnostic buffer to jump to the source.
4. Add a TaskExecutionFaultTask to the project if missing. Default behaviour is to call _TaskExecutionFault (alarm_S, logging, transition to STOP). The task must be assigned to the TaskExecutionFault system task in the project navigator (right-click the SIMOTION device → "Configure system tasks").
5. If you cannot find the original program, you can hot-restart the runtime from the CF card with p0010 = 30 on the SINAMICS side, but you will still need a valid project to operate the machine.

Reference: SIMOTION Communication Manual (109750213) and the SCOUT online help under "Connect to target system → Load / upload".

9. Profibus Sign-of-Life Fault F01912 / F01910 / F01902

F01912 / F01910 are raised when the SINAMICS Integrated does not see a valid sign-of-life counter from the SIMOTION DP master. F01902 is the same alarm for the clock-synchronous operational layer. The typical triggers and remedies are summarised below; the order matters because some of the faults mask others.

The remedy order is therefore: reload SIMOTION program → clear SIMOTION STOP → drive is back in the master sign-of-life cycle → re-acknowledge topology → reset SINAMICS faults → move the axis. Trying to clear F01912 with the SIMOTION in STOP will fail because the DP master is not emitting the global control telegram, and SINAMICS will keep raising the alarm once per Tmapc.

10. Commissioning Sequence (Field-Proven)

1. Replace Motor Module. Match DRIVE-CLiQ cable lengths to the previous wiring.
2. Power up. Note the new display "6" with flashing point.
3. Connect SCOUT to the SIMOTION over Ethernet. Configure PG/PC interface on the PROFINET / Ethernet port of the D4x5-2.
4. Open Accessible nodes. Expand the SIMOTION tree. The SINAMICS_Integrated must appear with the new module's type and firmware. If it is invisible, fix the PG/PC routing first.
5. Open HW Config, set the DP_Integrated subnet ID to the one SCOUT detected, save and compile.
6. Open the SINAMICS_Integrated online. The 30xxx / F01912 alarms should be visible. If you cannot reach the drive, go offline and double-check the PROFINET / PROFIBUS address of the SINAMICS_Integrated against the project (default 192 = bus address of the integrated CU).
7. Topology → Acknowledge change → p948 = 3 → automatic commissioning from DQI.
8. p640 = 9 A module rating. p10 = 0. p0977 = 1.
9. RAM → ROM. p0971 = 1.
10. Reload the SIMOTION project to the controller. Verify the TaskExecutionFaultTask is present in the project navigator.
11. Cold restart the controller. Wait until RUN LED is green.
12. Open SCOUT's "Control panel" for the axis, set enable, jog in inching mode (slow velocity 10 mm/s or 1 rpm depending on axis type). Verify encoder feedback and the actualPosition trace.
13. Switch language to English on the diagnostic buffer (SCOUT → Options → Language) to make the entries readable for the next operator.

Total downtime for this procedure: 30 to 60 minutes including program upload from the OEM. If you cannot obtain the original program, the machine can be commissioned in "empty project" mode with a generic axis template, but technology package data, HMI connections, and the Safety Integrated configuration are not recoverable from the controller alone.

11. Verification Checklist

• Ready LED on the D4x5-2 is green (or steady "8" if a fault is still latched).
• Seven-segment display shows a valid operating state (typically "0" or "5" depending on whether the drive is energised).
• SIMOTION diagnostic buffer contains no incoming events with class F / FX in the last 5 minutes.
• SINAMICS Integrated fault buffer is empty (r0945 = 0, r0947 = 0).
• r3996 / r9773 / r9794 (if used) are all "0" — "no fault present".
• Drive can be jogged from the SCOUT control panel at the configured velocity with no following error.
• PROFIBUS Integrated sign-of-life counter (r2050) increments once per Tmapc and does not miss a cycle.
• p9780 / p9781 = 0 (no passivation) if safety is configured.
• CU320-2 LED "RDY" green, "COM" green, "MOD" off or green.
• HMI reflects the actual machine state (operator no longer sees the red "Ready" lamp).

Troubleshooting matrix for residual issues after the procedure:

12. FAQ