Fixing Sinumerik 802D SL Sinamics S120 SERVO Status 31 Lockout

When a Sinumerik 802D SL controller commands a Sinamics S120 line-up but the SERVO drive object (DO) reports status word ZSW1 = 0x0231 / 0x0331 (status 31 - "Commissioning mode active, pulses suppressed, no ON command") while the CU_I is at status 10, the system is functioning correctly from a topology standpoint. The fault is a control-word routing and parameter-lockout problem. The drive receives the OFF/OFF2/OFF3 enable stack, but the master ON/OFF1 (p0840) signal is either unresolved, low, or the parameter write-protection (BICO lockout under p0922/p0300/p0400 dependency) is preventing the engineer from forcing it.

This reference covers the exact field scenario: an 1FG1102-1QD44-4AA2-Z SIMOTICS planetary geared servo motor, a PM340 (6SL3210-…) power module, a CUA31 Control Unit Adapter, and an 802D SL PCU with PP72/48 DIO module, where the engineer reports p0300=2, p0400[0..1]=0, no encoder, and a planned swap to CUA32 + AB incremental encoder. STARTER V5.4 SP3 is the canonical commissioning tool, selected for Windows 7 compatibility.

System Topology and Signal Flow

The 802D SL talks to the S120 in a fixed chain. Understanding the data path is essential before touching parameters.

Why SERVO Sits at Status 31

SINAMICS S120 drive objects report their state through ZSW1 (status word 1, r899/standard mapping at r2089[0]). Status 31 is the "closed-loop control ready, but no enable stack" condition. The drive has booted, run its power-on self test, and is sitting idle waiting for the bit pattern from the controller.

The engineer's MDA "Start" button drives DB31,..DBX6.0 (traversing key plus) on the PLC side, which the NCK converts into the axis enable stack DB31,..DBX2.1 and the channel-specific feed hold. These PLC bits are then mapped into the SINAMICS telegram bits that the SERVO expects to see at p0840, p0844, p0852.

The p0840 Lockout Chain (p0922, p0300, p0400)

The parameter lockout is correct behavior. SINAMICS protects motor, encoder, and power module matching by refusing BICO writes while a "drive object configuration" is in an inconsistent state.

p0922 - Drive Object Configuration

p0922 selects the functional drive object type. With p0922=0 the DO is undefined and BICO write protection is active on every parameter that depends on the DO type. The drive object is selected at first commissioning only – changing it requires the standard commissioning sequence (online → drive configuration → wizard).

p0300 / p0301 - Motor Type and Code

The drive checks the motor type/code combination against the power unit. The original engineer's p0300=2 (rotary servo motor) is correct for the 1FG, but p0301 (motor code number) is missing. The 1FG1xxx motors are not in the STARTER online motor list (they are catalog motors), so a 1FK-equivalent must be selected. The 1FG1102-1QD44-4AA2-Z is dimensionally close to a 1FK7060 or 1FK7061 in the SINAMICS parameter set.

p0400[0..1] - Encoder Type

With p0400[0]=0 and p0400[1]=0 the drive has no encoder configured on either channel. This triggers a write-protection cascade because BICO parameters that reference encoder signals (e.g., p0840 with feedback) become "unresolved". The engineer must set p0400[0]=1 (no encoder = simulation mode) explicitly to lift the lockout for the simulation path. To run the motor in real closed-loop, set p0400[0] to the matching encoder type (e.g., 9999 = user-defined incremental, then enter p0420 resolution).

Reading the Hexagonal p0840 Connection Strings

The field engineer observed the following BICO interconnections when tracing signals. These are the result of a STARTER "Standard telegram 116" macro download on the SERVO object. The long hex strings are normal – they are BICO source identifiers in the format 0xAABBCCDD where:

• 0xAA = drive object number (08 = SERVO on DO #8)
• 0xBB = parameter number high byte
• 0xCC = parameter number low byte
• 0xDD = bit index

The 0x2AFC parameter is the standard mapping of CU_STW1 (control word from the higher-level controller) into the SERVO. This is a 16-bit word transferred via telegram 116. The bit positions match the PROFIdrive profile AC1/AC4 standard.

Why p0840 Reports "Locked"

The drive refuses to overwrite p0840 with a static "1" because that breaks the PROFIdrive state machine. The drive expects to receive a clean control word from the NCK/PLC. Manually forcing p0840 to a constant 1 will work for a few seconds, but as soon as the NCK starts a new telegram cycle, it will overwrite p0840 again via BICO. The correct approach is to ensure the NCK is sending the ON bit (bit 0 of CU_STW1) – not to bypass the BICO.

Telegram 116 and Why Other Telegrams Fail

Telegram 116 is the Siemens-specific extended PROFIdrive telegram for the 802D SL ↔ S120 interface. It carries:

• Setpoints: NSOLL, encoder 1 actual value, encoder 2 actual value, additional setpoint (4 words = 8 bytes payload)
• Actual values: NIST, encoder actual values, status, additional actual value
• Process data: NCK↔drive control/status words (CU_STW1/CU_ZSW1) and torque/speed limits

Telegram 116 is the only Siemens 802D SL telegram that supports the dual-encoder configuration the 1FG planetary motor needs (one encoder on the motor, one on the load-side resolver, or both incremental). All DSC telegrams are excluded because the 802D SL does not implement the dynamic servo control extension.

STARTER 5.4 SP3 - The Only Supported Tooling

On a Windows 7 machine, only STARTER V5.4 SP3 (or V5.4 with HF11) provides the SINAMICS S120 drive object library that supports the 1FG motor via the "equivalent motor" function. Newer STARTER versions (V5.5, V5.6) require Windows 10 and may not load the older GSD for the CUA31.

Download and install in this order:

1. Install Drive ES Basic V5.4 SP3 from the Siemens support portal (this includes STARTER).
2. Apply HF11 from the same package.
3. Install the option package "SINAMICS S120 1FG Motor Support" – it provides the substitute motor list for 1FG1, 1FG2 series.
4. Connect via Ethernet (TCP/IP, port 135) to the CUA31. Default IP: 169.254.11.22 (set by SVC/SCOUT default).
5. Upload the actual parameter set to STARTER ("Load to PG"). Do not trust the parameter file from the previous engineer – it may be from a different motor.

On first upload, STARTER will display the topology view. Verify:

• CU_I (DO 0) appears with the correct firmware version (e.g., 4.5.x or 4.6.x for CUA31, 4.7+ for CUA32)
• SERVO (DO 1) appears with the correct motor type code (matching p0300=2, p0301 = selected equivalent)
• If p0975 reports a BICO error, the topology is broken – check the DRIVE-CLiQ cables and the chain order

Step-by-Step Commissioning Procedure

Follow this sequence exactly. Do not skip the p0922 step – it is the foundation of all other parameters.

Step 1 - Drive Configuration Reset (if necessary)

If the previous engineer's parameter set is corrupted, restore factory defaults:

1. Set p0010 = 30 (factory reset)
2. Set p9761 = 1 (password; or use the STARTER GUI)
3. Set p0970 = 1 (start reset)
4. Wait for the drive to complete the reset (the BOP will show "---")
5. Cycle the 24V control power on the CUA31

Step 2 - Drive Object Selection (p0922)

For the SERVO object that will drive the 1FG:

1. Set p0922 = 1 (servo drive object) on DO 1 (the SERVO). This is the first parameter that must be set after a factory reset.
2. Save with p0977 = 1 (RAM to ROM).

Step 3 - Power Unit Auto-Detection

The PM340 reports itself via DRIVE-CLiQ to the CUA31. Verify:

1. r0200 = PM340 power code (e.g., 6SL3210-1SE31-5AA0 = 15 kW). Cross-check the rating plate.
2. If r0200 = 0, the DRIVE-CLiQ link between the CUA31 and the PM340 is broken – check the CUA31 port assignment. CUA31 port X100 connects to the next DRIVE-CLiQ device (PM340), X200-X202 are free for additional drives.

Step 4 - Motor Selection (p0300, p0301)

The 1FG1102-1QD44-4AA2-Z is an 8-pole planetary geared servo motor in the SIMOTICS S-series family. The order code decodes as:

• 1FG1 - SIMOTICS planetary geared servo, square housing
• 102 - frame size 100, length 2 (medium)
• 1QD44 - shaft height, winding, options (here: standard shaft, incremental encoder prepared, holding brake, with key)
• 4AA2-Z - mechanical variant and Z options

Because the 1FG is not directly in the STARTER motor list, use the 1FK7060-2AF71-1AG1 as the equivalent (same 100 mm flange, similar torque, 8-pole rotor). In STARTER:

1. Open the SERVO drive object configuration
2. Click "Motor" → "Select another motor" → "1FK7" → "1FK7060"
3. Accept the substitute and let STARTER auto-populate p0300, p0301, p0304-p0311, p0314, p0320-p0335 from the substitute

The substitute values populate p0307 (rated power), p0308 (rated power factor / 0.71 typical for 1FK), p0311 (rated speed), p0314 (pole pair number = 4 for 8-pole), p0335 (motor cooling = 1 = natural convection). After the substitute write, the lockout at p0300 is lifted and p0300=2 (rotary servo) is set.

Step 5 - Encoder Configuration (p0400)

For the simulation path (no encoder connected):

1. Set p0400[0] = 1 (no encoder, simulation)
2. Set p0400[1] = 1 (no encoder on second channel)
3. If you want to test with the actual motor without encoder (open-loop VF control), use p1300 = 20 (open-loop torque control without encoder) – this is not recommended for a servo, but it lifts the lockout for commissioning checks

For the eventual encoder (after CUA32 swap and AB incremental connection):

1. Set p0400[0] = 9999 (user-defined encoder)
2. Set p0420 = 2048 (increments per revolution, for a typical 11-bit AB encoder; adjust to the actual encoder resolution from its plate)
3. Set p0421 = 1 (TTL, 5 V, AB with index pulse, 2048 ppr typical)
4. Set p0423 = 14 (HTL/TTL, 5 V or 24 V depending on the encoder; use 14 for 24 V HTL differential, 6 for 5 V TTL)
5. Set p0425[0] = 4 (fine resolution × 4)
6. Run automatic encoder calibration: p1990 = 1 then pulse enable briefly (the drive will measure the offset and store in p0431)

Step 6 - BICO Standard Telegram (p0015 macro)

The engineer's reading p0015 = 150001 is the macro for telegram 116 with CU_STW1/CU_ZSW1 control. This is correct for the 802D SL. If p0015 does not match the chosen telegram, the BICO wiring will not be loaded and p0840 will not resolve.

Step 7 - NCK Axis Machine Data

In the 802D SL, the axis machine data must agree with the SINAMICS configuration. The critical MDs are:

Why Motor Temperature Reads 200 °C

The engineer's screenshot showed a motor temperature of 200 °C. This is a classic symptom of a motor that has been modeled with a temperature model (KTY84 sensor) but has no actual sensor connected. The drive falls back to the winding temperature model with a default initial value of 200 °C and waits for the sensor data to update. Once p0300/p0301 are correctly set to the substitute motor, the temperature model parameters (p0601, p0604, p0605) are populated and the 200 °C reading disappears within a few minutes of operation.

If the 200 °C reading persists, the temperature sensor channel is incorrectly configured:

1. Set p0601 = 0 (no temperature sensor, use model) for testing, OR
2. Set p0601 = 1 (KTY84 sensor) and verify the wiring at the motor terminal box
3. Set p0604 = 130 (warning threshold) and p0605 = 155 (fault threshold) for the 1FG class B insulation

Tracing the "Waiting for Drive" State

On the NCK side, the alarm chain that produces the "Waiting for drive" message is:

1. NCK checks DB31,..DBX93.5 (drive ready) – if 0, alarm 25020 "Axis %1 drive %2 not ready"
2. NCK checks DB31,..DBX93.7 (pulses enabled) – if 0, alarm 25010 "Axis %1 hardware fault, no encoder signal" or similar
3. NCK checks the ZSW1 bit "Operation enabled" (bit 2 of CU_ZSW1 in telegram 116) – if 0, NCK displays "Waiting for drive" indefinitely in MDA/JOG

To trace, in STARTER open the trace recorder, select the SERVO object, add r899 (state word), r2089[0] (ZSW1), r47[0..2] (status word from CU), and trigger on a rising edge of r47.0 (drive ready). The trace will show exactly which bit is missing.

PP72/48 DIO Address Configuration

The PP72/48 connects to the PCU via PROFIBUS DP. The DIP switches on the back of the PP72/48 set the PROFIBUS station address. Common values for 802D SL are 9, 10, 11, 12 (X20, X21, X22, X23). The PCU reads these as digital inputs and outputs.

The engineer's question about X20 input driving p0840 is interesting. The X20 connector on a 802D SL PP72/48 corresponds to digital inputs I32.0-I35.7 in the PLC I/O image. The PLC program can read these and write to DB31,..DBX2.1 (axis enable), which then propagates to the drive as the ON bit in CU_STW1.

The X20 input should be wired through a PLC logic block, not directly to p0840. The BICO routing from input pin to drive parameter is a PLC responsibility on the 802D SL platform – it is not a direct wiring option.

Encoder Module Diagnosis (TPS54060 / EEPROM Issue)

The engineer's disassembly of the encoder module revealed a failed TPS54060 switching regulator. The TPS54060 is a TI 5-V/3-A step-down converter used in many third-party and Siemens encoder modules to derive the 5-V supply from the 24-V input. Symptoms of a TPS54060 failure:

• No 5 V on the encoder logic (check with oscilloscope at the TPS54060 output pin 9/10)
• EEPROM (24Cxx) VCC correct but SDA/SCL stuck low or high
• MCU clock present (crystal oscillation) but no bus traffic

After replacing the TPS54060, the engineer observed activity on the EEPROM's pin 5 (WP – write protect) but no data line transitions. This suggests the MCU is alive but the I2C bus is being held by another device, or the EEPROM has failed internally. Check:

1. Pull-up resistors on SDA/SCL (typically 4.7 kΩ to 5 V) – verify not burned open
2. Replace the EEPROM (24LC04, 24C16, or similar, depending on the encoder) with a blank part and re-initialize the encoder (manufacturer tool needed) – this is why Siemens recommends replacing the complete encoder module rather than field-repairing
3. Check the MCU's reset line (typically held high by a 10 kΩ pull-up) – if held low, the MCU is in perpetual reset

For the CUA32 swap with AB encoder: the CUA32 has onboard evaluation for HTL/TTL AB encoders via the X23 connector (15-pin D-sub). No separate Sensor Module is needed – the encoder connects directly to the CUA32. Pinout:

PLC Program Structure for 802D SL Axis Enable

The PLC program on the 802D SL (a Siemens S7-300 with a specialized firmware) needs to drive the following bits for the SERVO to receive the ON signal:

1. DB31,..DBX2.0 - Hardware limit switch plus
2. DB31,..DBX2.1 - Controller enable (this is what propagates to drive ON)
3. DB31,..DBX2.2 - Hardware limit switch minus
4. DB31,..DBX2.3 - Jog plus signal
5. DB31,..DBX2.4 - Jog minus signal
6. DB31,..DBX6.0 - Traversing key plus (from NCK) – this is what MDA "Start" drives

A minimal PLC program for the enable chain:

// FB1 - Axis enable management
// Call once per servo axis
// I 0.0 = Operator enable (PP72/48 X20 input 1)
// I 0.1 = Drive healthy (contact from infeed contactor)
// I 0.2 = Emergency stop OK

A I 0.0      // Operator enable
A I 0.1      // Drive healthy
A I 0.2      // E-stop OK
= DB31.DBX2.1 // Controller enable to NCK

A I 0.0
AN I 0.2
= DB31.DBX2.0 // Hardware limit + (use E-stop as limit)

A I 0.0
AN I 0.2
= DB31.DBX2.2 // Hardware limit - (use E-stop as limit)

Parameter Dump Procedure (Useful for Field Service)

To dump all parameters for sending to Siemens support, use STARTER:

1. Connect to the drive
2. Right-click the drive object → "Commissioning" → "Save parameter to PC"
3. Choose .par format (binary, complete) for an encrypted dump, or .txt format (text) for a human-readable dump

For a text dump of the SERVO object only, use STARTER's "Trace" function with a free trace on parameter number range 0-9999, or use the function generator on r0002 to scroll through the list.

Alternatively, on the BOP (Basic Operator Panel), use the navigator to step through parameters, but this is limited to 30 parameters at a time.

Troubleshooting Matrix

Verification Procedure (After Fix)

1. Power cycle the SINAMICS line-up (24V off for 10 seconds, then on)
2. Wait 30 seconds for DRIVE-CLiQ enumeration (CU_I ready, SERVO online)
3. Check r899[0] = 0x0231 (Ready to switch on)
4. From the NCK, jog the axis in JOG mode
5. Check r899[0] transitions: 0x0231 → 0x0331 → 0x0631 → 0x0731 (Operation enabled)
6. Observe motor movement and encoder feedback on the trace
7. Verify the S120 has no active faults: r0945 = 0, r0947 = 0, r2125 = 0
8. Back up the parameter set to STARTER and to a CF card if present

FAQ