KUKA Robot codes
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KUKA Robot Controller

Communication · Basic

Alarm KRC0212

KUKA Robot KRC0212 - ACKN BUS VOLTAGE CHARGING UNIT IS DEFECTIVE <KPS number>

This alarm indicates a failure in the ACKN (acknowledge) bus voltage charging unit, specifically that the optocoupler circuit on the KPS (KUKA Power Supply) module is not detecting current flow through the charging circuit. This typically occurs during the power-up sequence when the controller attempts to verify proper charging unit functionality before enabling the main servo drives.

KUKA RobotCommunicationBasic

KRC0212

KUKA Robot KRC0212 - ACKN BUS VOLTAGE CHARGING UNIT IS DEFECTIVE <KPS number>

ACKN BUS VOLTAGE CHARGING UNIT IS DEFECTIVE <KPS number>

This alarm indicates a failure in the ACKN (acknowledge) bus voltage charging unit, specifically that the optocoupler circuit on the KPS (KUKA Power Supply) module is not detecting current flow through the charging circuit. This typically occurs during the power-up sequence when the controller attempts to verify proper charging unit functionality before enabling the main servo drives.

Common Causes

  • Defective optocoupler component on the KPS circuit board
  • Broken or disconnected wiring between the charging unit and KPS optocoupler input
  • Faulty charging unit relay or contactor preventing current flow
  • Insufficient or unstable input voltage to the charging circuit
  • Failed power supply module or corrupted KPS firmware

Troubleshooting Steps

  1. 1Power cycle the KRC controller completely and attempt a warm restart to rule out transient faults
  2. 2Visually inspect the KPS module and all charging unit connections for loose connectors, burnt components, or visible damage
  3. 3Verify main AC input voltage and stability at the controller using a multimeter; confirm it meets KUKA specifications
  4. 4Check the charging unit contactor coil voltage and relay operation using diagnostic voltage measurements
  5. 5Use KUKA diagnostic software to read detailed error logs and monitor real-time KPS sensor values during startup sequence
  6. 6If voltage and connections are confirmed good, the KPS circuit board requires replacement; contact KUKA service for component availability and installation

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