Simotion D445-2 DP/PN Boot Failure: All-LEDs-Orange Diagnosis

Problem Overview: D445-2 DP/PN Will Not Complete Power-On Self-Test

A SIMOTION D445-2 DP/PN motion controller is reported dead-on-arrival at first power-up. Every front-panel LED illuminates continuously orange (amber) the moment 24 V DC is applied to the X124 connector, the seven-segment display cycles through the diagnostic sequence 3 - 3 - 4 - 6 and freezes there, the unit does not enumerate on PROFIBUS DP or PROFINET, and no combination of CF-CARD insertion, MRES (memory reset), or power-cycle will restore operation. Engineering tools (SIMOTION SCOUT, SIMOTION IT Diag, SCOUT TIA) cannot establish an online connection on any of the available service interfaces.

This pattern is unambiguous: the controller has failed its power-on self-test (POST) and the processor subsystem is unable to load firmware from non-volatile storage. The unit is unusable until the underlying hardware is repaired or replaced.

Affected Hardware and Order Numbers

The SIMOTION D445-2 DP/PN belongs to the SIMOTION D4x5-2 drive-based controller family. The most common variants and their MLFB (order) numbers are:

The D445-2 DP/PN integrates a SIMOTION CPU, a SINAMICS S120 drive control section, and dual PROFINET interfaces on a single control unit. Because the CPU, drive control, and PROFINET controller share the same backplane and the same firmware image stored on the CF card, a CPU failure takes every subsystem offline simultaneously — exactly the behaviour observed.

LED State Interpretation

The D445-2 front panel exposes ten diagnostic LEDs. Under normal boot each LED follows a defined colour/state pattern. When every LED is solid orange simultaneously, the controller is reporting a fatal error condition that occurs before firmware hand-off.

Display Code Analysis: 3 - 3 - 4 - 6

The two-digit seven-segment display on the SIMOTION D4x5-2 front panel performs a self-test sweep the moment 24 V is applied. The display cycles through digit pairs in sequence, then settles on a final state. The sequence 3 - 3 - 4 - 6 corresponds to one of the documented early-boot diagnostic codes used by the SIMOTION firmware loader.

Reading the digits in the order they appear after power-on, the sequence corresponds to a CPU-and-memory-level self-test that starts to pass the initial checks but never completes the firmware hand-off. On a healthy controller the display would briefly show test patterns (typically 0-1-2-3-4-5-6-7-8-9) and then go dark or show a two-digit status (e.g. "--" or "99") before the RDY LED turns green. A stuck-at-3-3-4-6 sequence means the boot ROM halted before firmware was loaded.

Root Cause Analysis

The combination of:

1. All ten LEDs latched orange simultaneously,
2. Display frozen at the 3-3-4-6 boot-test sequence,
3. No response to MRES, CF-CARD insertion, or power cycling,
4. No Ethernet / PROFIBUS / PROFINET service interface activity,

points unambiguously to a hardware failure of the SIMOTION CPU module. The most common root causes seen in the field on D4x5-2 hardware are:

• Flash/FRAM corruption beyond MRES recovery — the boot image in the on-board flash has been damaged (e.g. by interrupted firmware write, ESD, supply undervoltage during write) and the controller can no longer fall back to a valid image.
• SDRAM failure — a memory chip on the CPU board has failed the POST, halting the loader mid-sequence.
• Application-processor / FPGA failure — the main ASIC that orchestrates SIMOTION + SINAMICS has been damaged, often by surge, brown-out, or thermal stress.
• Backplane or connector damage — intermittent contact between the SIMOTION module and the SINAMICS drive section can mimic CPU failure but is rare on enclosed CU320-2 units.

Field Recovery Procedures Already Attempted

Before concluding that the controller is scrap, walk through the standard field-recovery ladder. Each step is documented in the SIMOTION D4x5-2 Commissioning and Hardware Installation Manual.

1. Verify the 24 V supply at X124. Measure between pins 1 (24 V) and 2 (M) of X124 with no load. Acceptable range is 20.4 V to 28.8 V. A sagging supply during the inrush of the SINAMICS line modules can corrupt the boot sequence.
2. Remove every option module. Pull the CBE30 PROFINET board (if fitted) and the TB30 terminal board from the option slot. A shorted option module can drag the entire controller down.
3. Remove the CF card and power up. A corrupted boot sector on the CF card can mimic a CPU fault. Without the card, a healthy CPU will still complete POST and show RDY orange-flashing.
4. Perform an MRES reset. With the controller powered, hold the MRES button for 3 s, release for 1 s, hold for 3 s again, then cycle power. The RDY LED should flash at ~2 Hz if the reset was accepted.
5. Try a known-good, freshly programmed CF card. Write the SIMOTION firmware image and project with SIMOTION SCOUT / SCOUT TIA on a bench PC and insert it.
6. Try a different PROFINET cable / service PC. Rule out a misconfigured service interface before assuming the CPU is dead.

If the controller still shows all-orange LEDs and the 3-3-4-6 sequence after every step above, the CPU board is not recoverable in the field.

HW Failure Confirmation

Siemens repair centres confirm the D4x5-2 hardware failure pattern with the following signature:

• All front-panel LEDs latch orange at first power-up.
• 7-segment display stops on a 3-3-4-6 or similar boot-test sequence.
• Internal POST logs (read via JTAG at the repair centre) show a halt in the SDRAM or flash-controller self-test.

For a definitive confirmation in the field without sending the unit away, request a Service Repair Order (RO) via the Siemens Industry Online Support portal. Provide the MLFB, serial number, and the symptom log (LED state, display code, supply voltage). Siemens will issue an RO number and a shipping label; turnaround is typically 5–10 working days for a D4x5-2 exchange, depending on whether a replacement unit is in stock at the regional repair hub.

Repair Path via Siemens

1. Open a support request on the Siemens Industry Online Support portal (support.industry.siemens.com) with the symptom, MLFB, and serial number.
2. Request an RMA / Repair Order. Quote the service contract ID if available — under an active SIMATIC/Siemens service contract, the repair is normally free or low-cost.
3. Ship the unit in anti-static packaging to the named Siemens repair hub. Include the CF card only if the project on it is still needed; Siemens will not return lost project data.
4. Siemens will either repair the board (component-level exchange) or replace it with a refurbished / new equivalent. The replacement is shipped with the firmware version current at the time of dispatch.
5. On receipt, re-flash the project from the latest engineering backup, re-commission the PROFINET / PROFIBUS topology, and run a controlled motion test before returning the line to production.

Migration Path: From SIMOTION D4x5-2 to SIMATIC Drive Controller / S7-1500

If the D4x5-2 is end-of-life, out-of-stock for repair, or the application is being modernised anyway, the official Siemens migration target is the SIMATIC Drive Controller (formerly known as the SIMATIC S7-1500 DRIve Controller, based on the ET 200SP / S7-1500 platform) or a stand-alone SIMATIC S7-1500 + SINAMICS S120 combination. The architecture and programming paradigm differ in important ways:

The full Siemens migration guidance — covering hardware substitution, programme conversion from MCC to PLCopen, and topology re-engineering — is documented in the official "Information for users changing from SIMOTION D4x5-2" page in the TIA Portal manual collection (TIA Portal: Information for users changing from SIMOTION D4x5-2).

Key migration constraints to plan for:

• Architecture re-design — The S7-1500 / Drive Controller is a PLC + drive, not an integrated motion controller. The MCC motion chart is replaced with PLCopen function blocks in SCL or LAD/FBD.
• Re-wiring of PROFINET topology — The PROFINET interfaces move from the SIMOTION module to the S7-1500 CPU; existing PROFINET device names and IP addresses must be re-assigned.
• Tooling switch — SIMOTION SCOUT projects cannot be auto-converted. The motion part must be manually rewritten against the PLCopen library; the drive commissioning (SINAMICS S120 parameters) can largely be migrated 1:1.
• Functional safety re-certification — Safety programs (SIMOTION F-CPU) must be re-implemented and re-validated in the S7-1500 F-CPU.

Verification After Repair or Replacement

Before returning a repaired or replaced D445-2 DP/PN to production, validate every functional layer:

1. Power-up sequence: On 24 V applied, RDY LED flashes green/orange for ~30 s, then settles solid green. RUN, STOP, SU/PF, SF, DP, DP/MPI, PN, SY/MT, OPT all return to their healthy idle states.
2. Service interface: Ping the X127 service port (default 169.254.11.22 / 192.168.0.1 depending on firmware) from a service laptop; the PROFINET diagnostics page should load.
3. Project load: From SIMOTION SCOUT / SCOUT TIA, perform a full project download to the CF card and verify the user program starts (RUN LED green).
4. PROFIBUS / PROFINET diagnostics: Confirm all configured slaves/devices appear in HW Config with no diagnostic alarms.
5. Motion test: Run each axis through a controlled low-speed profile and verify the actual position follows the setpoint within the configured tolerance window.
6. Safety test (if applicable):strong> Trigger each F-STOP path and verify the safe stop is executed within the configured response time.

Spare-Part and Lifecycle Considerations

The SIMOTION D4x5-2 family entered the product-discontinuation cycle; spare-parts availability is constrained to the official repair channel. To minimise downtime on a working fleet:

• Maintain at least one cold spare D445-2 DP/PN of the same MLFB and firmware version.
• Keep the latest engineering project (including drive parameter sets) backed up to a managed engineering server.
• Document the CF-card image (CRC and version) so a replacement unit can be brought up in minutes, not days.
• Subscribe to Siemens product-status notifications for the D4x5-2 so repair-cut-off dates trigger a planned migration.

Frequently Asked Questions