A35999 — TM: Unknown alarm

SINAMICS reports A35999 (TM: Unknown alarm) when a Terminal Module (TM) has issued an alarm that the firmware of the Control Unit (CU) cannot interpret — the CU simply does not know this alarm. The manual states that this can occur if the firmware on the Terminal Module is more recent than the firmware on the Control Unit, because newer component firmware can report alarms the older CU firmware has never seen. Depending on how the drive is configured, the same condition can also be output as a fault (F35999) or as a message without any reaction.

• A Terminal Module has issued an alarm that the Control Unit firmware cannot interpret.
• The firmware on the Terminal Module is more recent than the firmware on the Control Unit, so this new alarm is unknown to the CU.

1. Identify the unknown alarm: the drive stores its alarm number in r2124, to be interpreted as a decimal value. The message text itself is composed as 'New message: %1'.
2. If required, the significance of this new alarm can be read about in a more recent description of the Control Unit.
3. Close the firmware gap in one of two ways: replace the firmware on the Terminal Module by an older firmware version (r0158).
4. Alternatively, upgrade the firmware on the Control Unit (r0018) so the CU firmware matches the component again.

• Message value: 'New message: %1'.
• Alarm value (r2124, interpret decimal): alarm number — the number of the alarm that the Terminal Module has raised and that the Control Unit firmware could not interpret.

• r2124 (alarm value): here the drive stores the alarm number of the unknown TM message; interpret the value as a decimal to see which new alarm arrived.
• r0158 (listed in the parameter chapter as Voltage Sensing Module firmware version / VSM FW version): the remedy references this parameter when the Terminal Module firmware is to be replaced by an older version.
• r0018 (Control Unit firmware version): the remedy references this parameter when the Control Unit firmware is to be upgraded.

As an alarm, A35999 requires no acknowledgement and the drive takes no automatic action in response to it. If the drive configuration raises the same condition as a fault instead, that fault is acknowledged immediately — a POWER ON is sufficient. As long as the Terminal Module runs firmware newer than that of the Control Unit, alarms unknown to the CU can keep arriving, so the firmware downgrade on the TM or the upgrade of the CU is the actual remedy.