What it means
Encoder 3 reports that the speed it delivers is changing faster than the monitoring permits. The manuals word the message as Speed change not plausible
and as Speed difference per sampling rate exceeded
: for an HTL/TTL encoder, the alarm is raised when the speed change exceeds the value in p0492 — one entry describes the excess over several sampling cycles, the other as the difference between two sampling cycles. The change of the averaged speed actual value, if applicable, is monitored in the current controller sampling time. Depending on the drive configuration, the same condition can also be issued as a fault or as a message without reaction.
Why it appears
- For the HTL/TTL encoder connected on Encoder 3, the speed change exceeded the value in p0492 between sampling cycles.
- The monitoring also covers the change of the averaged speed actual value, if applicable, in the current controller sampling time.
What to check
- Check the tachometer feeder cable for interruptions.
- Check the grounding of the tachometer shielding.
- If required, increase the setting of p0492.
Reading the message value
- The drive stores an alarm value in r2124, to be interpreted as a decimal number.
- According to the manual, this alarm value serves only for internal Siemens troubleshooting; no further decoding is given.
Parameters the manual names
- p0492 — square-wave encoder maximum velocity difference per sampling cycle: for this code it is the threshold that the speed on Encoder 3 must not exceed; the remedy may be to increase its setting.
- r2124 — alarm value: holds the message value of this alarm, interpreted as a decimal number; for internal Siemens troubleshooting only.
Acknowledging and restarting
As an alarm, this message needs no acknowledgment and the drive does not trip because of it — it signals that the speed change on Encoder 3 exceeded p0492 at that moment. If the drive is configured to issue the same condition as a fault, the fault must be acknowledged IMMEDIATELY before the drive can run again; in the no-reaction variant, neither a reaction nor an acknowledgment applies.
The same on every family
Every manual that describes A33418 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. 3156 |
| G130, G150 | NONE | NONE | Actual position/speed value incorrect or not available (11) | Encoder 3 | SINAMICS G130, G150 List Manual · p. 1828 |
The drives this code lives on
A33418 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 A33418 mean on a SINAMICS drive?
Encoder 3 reports that the speed of the connected HTL/TTL encoder changed by more than the value in p0492 between sampling cycles. The change of the averaged speed actual value is monitored in the current controller sampling time.
Does A33418 stop the drive, and must it be acknowledged?
No. As an alarm the drive takes no automatic action and no acknowledgment is required. If the same condition is configured as a fault, it must be acknowledged IMMEDIATELY before the drive restarts.
How do I fix alarm A33418?
Check the tachometer feeder cable for interruptions and check the grounding of the tachometer shielding. If the signal path is sound, increase the setting of p0492.
What is the alarm value of A33418 in r2124?
The drive stores an alarm value in r2124, to be interpreted as a decimal number. The manual states that this value is only for internal Siemens troubleshooting.
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