What it means
F31899 Encoder 1: Unknown fault is raised when a fault occurred on the Sensor Module for encoder 1 that the firmware on the Control Unit (CU) cannot interpret. The manual names one typical situation for this: the firmware on the Sensor Module is more recent than the firmware on the Control Unit, so the Control Unit does not know the fault that was reported. The number of the unknown fault is stored in r0949. Depending on how the drive is configured, the same condition can also be issued as an alarm or with no reaction at all.
Why it appears
- A fault occurred on the Sensor Module for encoder 1 that cannot be interpreted by the firmware on the Control Unit.
- The manual names a firmware version mismatch as the trigger: the Sensor Module runs a firmware that is more recent than the firmware on the Control Unit.
What to check
- Read the fault value in r0949, interpreting it as a decimal number — it contains the fault number that the Sensor Module reported.
- If you need to know what this new fault number means, look it up in a more recent description of the Control Unit.
- Compare the firmware version of the Sensor Module (r0148) with the firmware version of the Control Unit (r0018).
- Replace the firmware on the Sensor Module by an older firmware version, or upgrade the firmware on the Control Unit — one of the two measures resolves the version mismatch behind this fault.
Reading the message value
- Fault value (r0949, interpret decimal): fault number — the number of the fault reported by the Sensor Module for encoder 1, which this Control Unit firmware cannot interpret.
- The manual notes:
If required, the significance of this new fault can be read about in a more recent description of the Control Unit.
Parameters the manual names
- r0949 — fault value; for this code read it as a decimal number to obtain the unknown fault number.
- r0148 — Sensor Module firmware version; read it to see which firmware is on the Sensor Module for encoder 1 before replacing it with an older version.
- r0018 — Control Unit firmware version; this is the firmware to upgrade if you choose the upgrade path.
- p0491 — motor encoder fault response (ENCODER); the note on this fault points to this parameter for the configured response to encoder faults.
Acknowledging and restarting
The manual gives no reset sequence beyond the two firmware measures above. Once the Sensor Module and Control Unit firmware have been matched again — older firmware on the Sensor Module or an upgraded Control Unit — acknowledge the fault and restart the drive. The fault can be acknowledged immediately, and a POWER ON also removes it.
What differs between the drive families
Straight from the manuals' own fields — F31899 is not described identically everywhere.
| Drive family | Reaction | Acknowledge | Message class | Component | Manual |
|---|---|---|---|---|---|
| S120, S150 | Infeed: OFF2 (NONE, OFF1) Servo: ENCODER (IASC/DCBRK, NONE, OFF1, OFF2, OFF3, STOP2) Vector: ENCODER (IASC/DCBRK, NONE, OFF1, OFF2, OFF3, STOP2) Hla: ENCODER (NONE, OFF1, OFF2, OFF3, STOP2) | — | Actual position/speed value incorrect or not available (11) | Sensor Module Encoder 1 | SINAMICS S120, S150 List Manual · p. 3074 |
| G130, G150 | Vector: ENCODER (IASC/DCBRK, NONE, OFF1, OFF2, OFF3, STOP2) Infeed: OFF2 (NONE, OFF1) | IMMEDIATELY (POWER ON) | Actual position/speed value incorrect or not available (11) | Sensor Module Encoder 1 | SINAMICS G130, G150 List Manual · p. 1758 |
The drives this code lives on
F31899 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 fault F31899 (Encoder 1: Unknown fault) mean on a SINAMICS drive?
The Sensor Module for encoder 1 has reported a fault that the firmware on the Control Unit cannot interpret. The typical reason is that the Sensor Module firmware is more recent than the Control Unit firmware.
How do I fix F31899?
Read the unknown fault number in r0949 (decimal), compare the Sensor Module firmware version in r0148 with the Control Unit firmware version in r0018, and then either load older firmware onto the Sensor Module or upgrade the Control Unit firmware.
Where can I find what the unknown fault number behind F31899 means?
The manual states that the significance of this new fault can be read about in a more recent description of the Control Unit.
Can F31899 also appear as an alarm?
Yes. Depending on the drive's configuration, the same condition can also be issued as an alarm or with no reaction at all.
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 F31xxx group · SINAMICS manuals · Siemens manuals