F34950 — VSM: Internal software error

F34950 is raised when the Voltage Sensing Module (VSM) detects an internal software error. The drive coasts down (OFF2), and the fault is only cleared at power up — the converter will not restart until it has been switched off and on again. The manual gives no customer-level detail about what failed inside the module: the fault value identifies the fault source, but the manual states it is Only for internal Siemens troubleshooting.

• An internal software error has occurred inside the Voltage Sensing Module (VSM).

1. If the fault occurs, check whether a later firmware version is available for the Voltage Sensing Module (VSM) and upgrade the module's firmware if necessary.
2. If the error persists, contact Technical Support and quote the fault value from r0949, interpreted as a decimal number — the manual designates this information for internal Siemens troubleshooting, so it is the support engineer who can evaluate it.

• The drive stores information about the fault source in r0949; the manual instructs to interpret the value as a decimal number.
• No bit or value decoding is printed for this code — the content is intended only for internal Siemens troubleshooting, so there is no self-help reading of the value.

• r0949 — read the fault value of F34950 here; for this code it holds the fault source as a decimal number and is only meaningful to Siemens Technical Support.

This fault belongs to the POWER ON acknowledge class: it cannot be cleared with an ordinary acknowledge, only by switching the converter power supply off and on again. After the power-up reset the drive can be restarted. If F34950 returns, follow the remedy above — upgrade the VSM firmware if a later version exists, otherwise contact Technical Support.