What it means
A34905 reports that the Control Unit attempted to write an illegal parameter value to the Voltage Sensing Module (VSM). Depending on how the drive is configured, the same condition can also be output as a fault or as a message without any automatic reaction. The alarm carries no message value, so there is no additional decoding to read.
Why it appears
- The Control Unit has sent a parameter value to the Voltage Sensing Module (VSM) that the module does not accept as a legal value.
What to check
- Check whether the firmware version of the VSM (r0158) matches the firmware version of the Control Unit (r0018). The readme.txt file on the memory card states which firmware versions match each other.
- If required, replace the Voltage Sensing Module.
Parameters the manual names
- r0158 — shows the firmware version of the Voltage Sensing Module (VSM); read it here to compare it against the Control Unit firmware version.
- r0018 — shows the firmware version of the Control Unit; read it here to compare it against the VSM firmware version.
Acknowledging and restarting
When the condition is output as an alarm, no acknowledgement is required. If it is output as a fault, acknowledge it immediately by switching the power supply off and on again (POWER ON). In every variant of this message the drive takes no automatic reaction — it does not trip or change its operating state on its own.
The same on every family
Every manual that describes A34905 gives it the same reaction, acknowledgement and message class.
| Drive family | Reaction | Acknowledge | Message class | Component | Manual |
|---|---|---|---|---|---|
| S120, S150 | NONE | NONE | Hardware/software error (1) | Voltage Sensing Module (VSM) | SINAMICS S120, S150 List Manual · p. 3195 |
| G130, G150 | NONE | NONE | Hardware/software error (1) | Voltage Sensing Module (VSM) | SINAMICS G130, G150 List Manual · p. 1864 |
The drives this code lives on
A34905 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 A34905 on a SINAMICS drive mean?
It means the Control Unit attempted to write an illegal parameter value to the Voltage Sensing Module (VSM). Depending on the drive configuration, the same condition can also appear as a fault or as a message without a reaction.
How do I fix A34905 (VSM: Parameter access)?
Compare the VSM firmware version r0158 with the Control Unit firmware version r0018; the readme.txt file on the memory card lists which versions match each other. If required, replace the Voltage Sensing Module.
Does A34905 have to be acknowledged?
As an alarm it needs no acknowledgement. If the drive outputs the condition as a fault, acknowledge it immediately by switching the power supply off and on again (POWER ON).
Which firmware versions of VSM and Control Unit match for A34905?
The manual does not print version numbers with this message; it refers to the readme.txt file on the memory card, which lists the firmware versions that match each other.
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 A34xxx group · SINAMICS manuals · Siemens manuals