What it means
Encoder 3 is checked every time its zero pulse is passed: the drive compares the incremental position at the mark with the reference it took earlier. The first zero mark passed supplies the reference point for all subsequent checks. With equidistant zero marks, every further mark must lie at n times the distance referred to that first mark; with distance-coded zero marks, the first zero mark pair is the reference and every further pair must keep the expected distance to it. When a mark is passed and the incremental position deviates from this pattern, the drive raises A33431. Depending on the drive's configuration, the same condition can also be issued as a fault or with no reaction.
Why it appears
- When the encoder's zero pulse is passed, the incremental position read from Encoder 3 deviates from the reference pattern established by the first zero mark.
- Encoder cables that are not routed in compliance with EMC can disturb the encoder signals.
- A plug connection in the encoder signal path is faulty.
- The encoder or the encoder cable is defective.
- The coding disk is dirty, or strong magnetic fields are acting on the encoder.
What to check
- Check that the encoder cables are routed in compliance with EMC.
- Check the plug connections.
- Replace the encoder or the encoder cable.
- Clean the coding disk or remove strong magnetic fields.
Reading the message value
- The drive writes the alarm value into r2124; interpret it as a decimal number.
- The value is the deviation in quadrants, where 1 pulse = 4 quadrants.
Parameters the manual names
- r2124 — alarm value: read off how large the position deviation is; interpret the number as a decimal and as quadrants (1 pulse = 4 quadrants).
Acknowledging and restarting
A33431 appears as an alarm; depending on the drive's configuration, the same condition can also be issued as a fault or with no reaction. As an alarm it needs no acknowledgment — remedy the encoder signal path so that the zero marks again match the reference taken from the first mark passed. If the drive raises the condition as a fault, that fault must be acknowledged immediately.
The same on every family
Every manual that describes A33431 gives it the same reaction, acknowledgement and message class.
| Drive family | Reaction | Acknowledge | Message class | Component | Manual |
|---|---|---|---|---|---|
| S120, S150 | NONE | NONE | Actual position/speed value incorrect or not available (11) | Encoder 3 | SINAMICS S120, S150 List Manual · p. 3159 |
| G130, G150 | NONE | NONE | Actual position/speed value incorrect or not available (11) | Encoder 3 | SINAMICS G130, G150 List Manual · p. 1831 |
The drives this code lives on
A33431 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 A33431 mean on a SINAMICS drive?
It is an Encoder 3 message: when the encoder's zero pulse is passed, the drive detected a deviation in the incremental position. The zero marks no longer match the reference point taken from the first mark that was passed.
How do I read the alarm value of A33431?
The alarm value is stored in r2124 and is interpreted as a decimal number. It indicates the deviation in quadrants, with 1 pulse corresponding to 4 quadrants.
What should I check when A33431 appears?
Check that the encoder cables are routed in compliance with EMC and check the plug connections. If the alarm persists, replace the encoder or the encoder cable, and clean the coding disk or remove strong magnetic fields.
Does A33431 have to be acknowledged?
As an alarm, no acknowledgment is required. If the drive is configured to issue the same condition as a fault, that fault must be acknowledged immediately.
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 A33xxx group · SINAMICS manuals · Siemens manuals