Resolving P0601 Illegal Parameter Value on SINAMICS S120 PT1000

Resolving P0601 Illegal Parameter Value on SINAMICS S120 When Reconfiguring Motor Temperature Sensor from KTY84 to PT1000

1. Problem Statement: P0601 Illegal Parameter Value on SINAMICS S120

When a SINAMICS S120 drive (CU310-2 or CU320-2 Control Unit) is delivered with the default motor temperature sensor configured as KTY84, and the actual motor is wound with a PT1000 RTD, the commissioning engineer will typically attempt to change p0601 from 2 (KTY84) to 6 (PT1000). On older firmware versions the drive rejects this write attempt with one of the following symptoms:

• STARTER / Startdrive commissioning tool reports: "Illegal parameter value" or "Value cannot be accepted".
• BOP / IOP operator panel shows alarm A07910 (drive: motor overtemperature warning) on the next power-up.
• The parameter index write is silently rejected; p0601 reverts to its previous value.
• Higher-level controller reports F08501 (PROFINET / PROFIBUS sign-of-life failure) when the parameter write is initiated from a PLC and the drive holds the slot in a fault state for the bus cycle.

The drive's sensor evaluation logic on the SMC20 / SMC30 is firmware-dependent. The PT1000 enumerator value 6 was introduced to the SINAMICS S120 firmware roadmap in V4.5 SPx and is fully validated from V4.7 onward. Drive objects delivered with V4.3, V4.4, or early V4.5 builds do not know the PT1000 encoding and refuse the write with the illegal-value response.

2. Affected Hardware and Firmware Versions

Component	Order Number (MLFB)	Minimum Firmware for p0601 = 6	Notes
CU310-2 PN	6SL3040-1LA01-0AA0	V4.7 (4.7.x)	Control Unit; PT1000 supported from V4.5 SP3, validated in V4.7
CU310-2 DP	6SL3040-1LA00-0AA0	V4.7	Same firmware family as PN variant
CU320-2 PN	6SL3040-1MA01-0AA0	V4.7	Most common CU in S120 booksize cabinet
CU320-2 DP	6SL3040-1MA00-0AA0	V4.7	PROFIBUS variant
SMC20	6SL3055-0AA00-5AB1	Ships with CU firmware (V4.7)	Sensor Module Cabinet-Mounted; resolver / incremental encoder interface with two temperature channels
SMC30	6SL3055-0AA00-5CA2	Ships with CU firmware (V4.7)	Encoder interface with TTL/HTL and two temperature channels

3. Root Cause: Sensor Type Encoding and Firmware Dependency

Parameter p0601 is a coded enumerator. The SINAMICS parameter list defines the sensor types as follows:

p0601 Value	Sensor Type	Cold Resistance (25 °C, approx.)	Hot Resistance (200 °C, approx.)	Curve
0	No sensor	-	-	Temperature monitoring disabled
1	PTC thermistor (DIN 44081 / 44082)	150 - 300 Ω	≥ 2000 Ω	Switching characteristic; trip at fixed resistance threshold
2	KTY84	~ 500 Ω	~ 2600 Ω	Linear PTC silicon sensor
4	PT100 (RTD)	100 Ω @ 0 °C	~ 175 Ω	Platinum RTD, 3850 ppm/K (IEC 60751)
5	PT1000 (legacy encoding, V4.5 SP1)	1000 Ω @ 0 °C	~ 1750 Ω	Platinum RTD, 3850 ppm/K
6	PT1000 (current encoding)	~ 1090 Ω	~ 1750 Ω	Platinum RTD, 3850 ppm/K

The "Illegal parameter value" response occurs when the firmware on the active drive object does not contain the enumerator entry 6 (or 5, depending on firmware generation) for PT1000. The firmware's parameter validation table only enumerates the sensor types known at compile time. Older V4.3 / V4.4 / V4.5 builds know the set {0, 1, 2, 4}; only V4.5 SP3 and V4.7+ know the full set {0, 1, 2, 4, 5, 6}. When the commissioning PC writes p0601 = 6, the drive cross-checks the requested value against the firmware's enum table. If 6 is not present, the value is rejected and a parameter fault is raised locally on the drive object. The p0003 access level must also be set to 2 (Expert) or 3 (Service) for the write to be accepted once the firmware supports the value. The condition has nothing to do with:

• Hardware damage on the SMC20 / SMC30.
• Wrong wiring of the sensor (although wiring errors produce different faults - see Section 8).
• Encoder type selection in p0400.
• Closed-loop control structure (servo / vector / U/f).
• Motor data set selection (p013x).

4. Sensor Resistance Characteristics and Compatibility

The KTY84 and PT1000 are both PTC sensors, but their resistance curves are not interchangeable. The drive's temperature evaluation circuit must be configured for the specific curve. For the KTY84 the cold-state resistance at 25 °C is approximately 500 Ω. At the motor's typical insulation class F limit of 155 °C the resistance rises to roughly 2200 Ω; at class H limit of 180 °C the resistance approaches 2600 Ω. The curve is documented in the KTY84 datasheet and approximated piecewise-linearly in the SINAMICS firmware. For the PT1000 the cold-state resistance at 25 °C is approximately 1090 Ω. At 155 °C the resistance is roughly 1580 Ω; at 200 °C it reaches approximately 1750 Ω. The curve follows the IEC 60751 platinum standard with a temperature coefficient of 3850 ppm/K, and the drive's firmware computes the equivalent temperature using a piecewise-linear approximation of the standard. The SINAMICS S120 internal evaluation uses two thresholds:

• Motor temperature warning threshold - default p0604 = 130 °C (class F).
• Motor temperature fault threshold - default p0605 = 150 °C (class F).

The firmware's temperature model coefficients are unique per enumerator value and cannot be mixed. If the drive is wired and configured for KTY84 but the actual motor sensor is PT1000, the drive will interpret the PT1000's 1090 Ω cold-state reading as approximately 75 °C and will raise a motor overtemperature warning on first power-up. This is a strong indicator that p0601 must be changed.

5. Wiring the PT1000 to SMC20 / SMC30

The PT1000 is wired to the encoder module's temperature sensor input, not to the encoder signal pins. The pinout differs between SMC20 and SMC30.

SMC20 Terminal Assignment

Pin	Signal	Function
X520 pin 1	+TEMP1	Positive temperature sensor input, channel 1
X520 pin 2	-TEMP1	Negative temperature sensor input, channel 1
X520 pin 13	+TEMP2 / +TEMP (motor)	Positive temperature sensor input, channel 2 (motor)
X520 pin 25	-TEMP2 / -TEMP (motor)	Negative temperature sensor input, channel 2 (motor)

For a standard S120 drive-cliq topology with the motor's PT1000 routed through the power cable's brake and temperature conductors, connect the PT1000 to X520 pin 13 (+TEMP) and X520 pin 25 (-TEMP). Use a shielded, twisted pair and ground the shield at the cabinet end only to avoid common-mode noise pickup on the high-impedance RTD measurement circuit.

SMC30 Terminal Assignment

Terminal	Signal	Function
X520.1	1TP1 / +Temp	Positive temperature sensor input, channel 1
X520.2	1TP2 / -Temp	Negative temperature sensor input, channel 1
X520.3	2TP1 / +Temp2	Positive temperature sensor input, channel 2
X520.4	2TP2 / -Temp2	Negative temperature sensor input, channel 2

For a single-channel PT1000 connection, use X520.1 and X520.2 on the SMC30. The cable shield should be landed on the encoder module's shield clamp and bonded to the cabinet PE bus.

6. Step-by-Step Resolution: Firmware Update Procedure

The illegal-value response on p0601 is resolved by upgrading the Control Unit firmware to V4.7 or later. The following procedure is the validated path for CU310-2 and CU320-2, as documented in the Siemens Industry Online Support portal.

1. Identify the active Control Unit on the S120 drive. In STARTER or Startdrive, open the project, expand the drive navigator, and note the MLFB and current firmware version under "Control Unit" -> "Properties" -> "Diagnostics" -> "Firmware version".
2. Download the latest SINAMICS S120 firmware package from the Siemens Industry Online Support portal. The article 109483388 contains the V4.7 firmware and the update instructions.
3. Extract the ZIP archive. The package contains a folder "FW_S120" with the binary files for the Control Unit, SMC20, SMC30, and any connected TM (Terminal Module) or Motor Module.
4. Copy the firmware files to a Siemens-compatible CF card (for CU310-2 / CU320-2 the supported card is a 6SL3054-0xx00-1BA0 or any industrial CF card ≤ 8 GB formatted as FAT32).
5. Insert the CF card into the CU320-2 / CU310-2. Power-cycle the drive system. The CU reads the firmware images from the CF card and updates itself, then automatically cascades the update to the connected SMC20 / SMC30 over the DRIVE-CLiQ link.
6. Wait for the Control Unit to display "RUN" on its 7-segment display. The full update cycle typically takes 3 - 8 minutes; do not remove power during this interval.
7. After the update, re-import the project into STARTER / Startdrive. The commissioning tool will detect the new firmware and may request a project upgrade. Confirm the upgrade.
8. Reconnect online to the drive and re-attempt the parameter write p0601 = 6. The drive will accept the value once the firmware supports the enumerator.

7. Step-by-Step Configuration: P0600 / P0601 Settings

Once the firmware supports p0601 = 6, configure the temperature monitoring as follows.

1. Confirm access level. On the BOP, set p0003 = 2 (Expert access) or p0003 = 3 (Service access). On STARTER / Startdrive, right-click the drive and select "Expert list" to expose all parameters.
2. Activate the temperature sensor input. Set p0600 = 1 to use the motor temperature sensor on channel 1 (the default for motors with a single PT1000). If the motor has two PT1000 sensors and the second channel is wired, set p0600 = 2 instead.
3. Set p0601 = 6 for the PT1000 RTD.
4. Configure the warning and fault thresholds. For a class F motor:

   
   p0604 = 130   ; Motor temperature warning threshold (°C)
   p0605 = 150   ; Motor temperature fault threshold (°C)
   

   For a class H motor:

   
   p0604 = 150
   p0605 = 180
   

5. Set the sensor fault reaction. p0607 = 0 generates fault F07011 on sensor open-circuit / short-circuit. p0607 = 1 generates alarm A07910 only. Use p0607 = 0 for safety-relevant applications.
6. If the drive is part of a vector-controlled group, also configure p0610 = 4 to enable the motor temperature model that compensates the resistance estimate for rotor heating.
7. Copy parameters from RAM to ROM with p0971 = 1 so the change survives a power cycle.

8. Verification and Commissioning Checks

After the parameter change, perform the following verification:

Check	Expected Result	How to Read
Read back p0601	6 (PT1000)	STARTER parameter list or r0601 if exposed
Read r0035 (motor temperature)	Ambient + sensor offset (typically 20 - 40 °C cold)	STARTER control panel, "Temperature" trace
Disconnect sensor wire	Drive raises F07011 within 1 - 2 seconds	Fault buffer view
Short sensor wires	Drive raises F07011 immediately	Fault buffer view
Heat sensor with hot air gun or hand	r0035 climbs proportionally	STARTER trace; should reach 50 - 80 °C under hand
Save parameters	p0971 = 1 returns 0; drive reboots with new values	STARTER / Startdrive online dialog

If r0035 reads -200 °C (or another extreme negative value) the sensor wires are open. If r0035 reads +250 °C the wires are shorted. If r0035 reads correctly at standstill but drifts with motor current, the encoder cable shield is not properly grounded and noise is coupling into the high-impedance RTD measurement circuit. In that case re-terminate the shield at the cabinet end only and use a twisted pair for the RTD conductors.

9. Troubleshooting Matrix

Symptom	Likely Cause	Resolution
p0601 = 6 write returns "Illegal parameter value"	CU firmware older than V4.7; p0003 access level too low	Update CU firmware per Siemens KB 109483388; set p0003 = 2 or 3
p0601 = 6 write accepted but r0035 = -200 °C	Sensor open-circuit or wiring reversed	Check X520 pin 13 / 25 (SMC20) or X520.1 / X520.2 (SMC30) for continuity; verify polarity
p0601 = 6 accepted, r0035 jumps to +250 °C at power-up	Sensor wires shorted	Megger the sensor lead; check for pinched insulation
r0035 drifts with motor current (not with cooling)	Encoder cable shield not grounded; RTD measurement noise	Ground shield at cabinet end only, use twisted pair
Drive reports F08501 after parameter change from PLC	Controller timed out waiting for drive to accept write	Reduce bus cycle time, increase controller timeout, retry write
Drive reports F07011 even at cold ambient	p0601 still set to KTY84 (2) but actual sensor is PT1000; PT1000 cold resistance (1090 Ω) mis-read as ~75 °C by KTY84 curve	Change p0601 to 6 and update firmware if needed
Drive reports F07011 only during loading	Motor genuinely overheating; PT1000 correctly reading temperature but thresholds too low	Reduce load; check ventilation; verify p0604 / p0605 against motor class F vs class H limits
p0601 write OK from STARTER but rejected by PLC	PLC is using a pre-defined parameter list (e.g. S7 "WRREC" with a fixed parameter set) compiled against an older firmware	Re-compile the parameter set against V4.7 firmware in STARTER, re-import to the PLC project
r0035 reads -273 °C / -200 °C at all times	Sensor wire broken, or p0600 / p0601 set to wrong channel	Verify which channel the sensor is wired to; swap p0600 between 1 and 2 if multi-channel
SMC20 / SMC30 firmware version does not change after CU update	DRIVE-CLiQ connection interrupted during cascade update	Verify DRIVE-CLiQ LED status, reseat connectors, retry firmware update

10. Frequently Asked Questions