What it means
A35921 is the Terminal Module (TM) message for temperature sensor channel 1: while evaluating the sensor connected to this channel, the drive found an error. The message value carries the alarm value, which the drive stores in r2124 — read as a decimal number, it says what was wrong: 1 means wire breakage or a sensor that is not connected, 2 means the measured resistance is too low. The drive evaluates PTC thermistors, KTY84, PT100 and PT1000 sensors this way, and a TM150 applies its own resistance thresholds. Depending on how the drive is configured, the same condition can also be output as a fault or as a message with no reaction (N) instead of this alarm.
Why it appears
- The Terminal Module detected an error while evaluating the temperature sensor connected to channel 1.
- Wire breakage, or the sensor is not connected (alarm value 1 in r2124).
- The measured resistance of the sensor is too low (alarm value 2 in r2124).
What to check
- Read the alarm value in r2124, interpreting it as a decimal number: 1 means wire breakage or a sensor that is not connected, 2 means the measured resistance is too low.
- Make sure that the sensor is connected correctly.
- Compare the resistance of the connected sensor type — PTC thermistor, KTY84, PT100 or PT1000 — with the thresholds given in the alarm value decoding; a TM150 uses its own thresholds.
- Replace the sensor.
Reading the message value
- The drive writes the alarm value into r2124; interpret the value as a decimal number.
- 1 — wire breakage or sensor not connected: KTY84: R > 1630 Ohm (TM150: R > 2170 Ohm), PT100: R > 194 Ohm, PT1000: R > 1720 Ohm (TM150: R > 1944 Ohm).
- 2 — measured resistance too low: PTC thermistor: R < 20 Ohm, KTY84: R < 50 Ohm (TM150: R < 180 Ohm), PT100: R < 60 Ohm, PT1000: R < 603 Ohm.
Parameters the manual names
- r2124 — alarm value of this message; read it as a decimal number to tell whether channel 1 signalled wire breakage or a missing sensor (1) or a too-low measured resistance (2).
Acknowledging and restarting
As an alarm the message requires no acknowledgement, and the drive takes no action when it appears. If the drive is configured to output the same condition as a fault, that fault is acknowledged immediately (POWER ON); output as a message with no reaction (N), it likewise requires no acknowledgement.
The same on every family
Every manual that describes A35921 gives it the same reaction, acknowledgement and message class.
| Drive family | Reaction | Acknowledge | Message class | Component | Manual |
|---|---|---|---|---|---|
| S120, S150 | NONE | NONE | External measured value / signal state outside the permissible range (16) | Terminal Module (TM) | SINAMICS S120, S150 List Manual · p. 3244 |
| G130, G150 | NONE | NONE | External measured value / signal state outside the permissible range (16) | Terminal Module (TM) | SINAMICS G130, G150 List Manual · p. 1906 |
The drives this code lives on
A35921 is described for G130, G150, S120, S150. These are the converters of those families in our catalogue — price on request.
Questions technicians ask
What does alarm A35921 mean on a SINAMICS drive?
It is the Terminal Module message for temperature sensor channel 1: an error occurred while evaluating the sensor — either wire breakage or the sensor is not connected (alarm value 1), or the measured resistance is too low (alarm value 2).
How do I fix A35921?
Make sure that the sensor is connected correctly and, if the error persists, replace the sensor. The alarm value in r2124 tells you which of the two conditions the drive detected.
Does A35921 have to be acknowledged?
No — as an alarm it requires no acknowledgement. If the drive is configured to raise the condition as a fault, that fault is acknowledged immediately (POWER ON).
Which resistance thresholds trigger A35921?
For alarm value 1 (wire breakage / not connected): KTY84 above 1630 Ohm (TM150: 2170 Ohm), PT100 above 194 Ohm, PT1000 above 1720 Ohm (TM150: 1944 Ohm). For alarm value 2 (too low): PTC thermistor below 20 Ohm, KTY84 below 50 Ohm (TM150: 180 Ohm), PT100 below 60 Ohm, PT1000 below 603 Ohm.
Codes next to this one
Source
Written from Siemens' own List Manuals and operating instructions; every number, designation and parameter on this page is checked against them before publication.
All SINAMICS codes: fault and alarm codes · the A35xxx group · SINAMICS manuals · Siemens manuals