121
LV1-Trip (Low voltage supply undervoltage)
Kuka · KR C2 Robot Controller
What does 121 mean?
This fault indicates an undervoltage condition in the low voltage supply for the KPS-600. This means the control power supply voltage is below the operational threshold, which can affect control unit stability and lead to unexpected shutdowns or erratic behavior.
Repair Steps
- 1
Measure the control voltage supply (e.g., 24VDC) at the designated control input terminals.
- 2
Verify the output voltage of the external control power supply.
- 3
Inspect the control wiring for excessive voltage drop due to long cable runs or undersized wire gauge.
Verified technical data. Last updated: March 2026
Source: Kuka KR C2 Robot Controller