Decoding the LED Indicators on the Sensor Module Cabinet-Mounted SMC20 for Sinamics S120 AC Drive

Sinamics S120 Family


The Siemens Sinamics S120 AC Drive system is versatile and robust. One of its key components is the Sensor Module Cabinet-Mounted SMC20. This module evaluates encoder signals and transmits the speed, actual position value, rotor position, and, if necessary, the motor temperature via DRIVE-CLiQ to the Control Unit. Understanding the LED indicators on the SMC20 can help you monitor the module's status and troubleshoot any issues that may arise.

LED Indicators and Their Meanings:

The SMC20 has several LED indicators, each with different colors and statuses. Here's what each LED indicator means:


  • Off: The electronics power supply is missing or outside the permissible tolerance range.
  • Green (Continuous light): The component is ready for operation. Cyclic DRIVE-CLiQ communication is taking place.
  • Orange (Continuous light): DRIVE-CLiQ communication is being established.
  • Red (Continuous light): This component has at least one fault. Note: The LED is activated irrespective of whether the corresponding messages have been reconfigured. To remedy this, remove and acknowledge the fault.
  • Green/Red (0.5 Hz flashing light): Firmware is being downloaded.
  • Green/Red (2 Hz flashing light): Firmware download is complete. The system waits for POWER ON. To remedy this, carry out a POWER ON.
  • Green/Orange or Red/Orange (Flashing light): Component recognition via LED is activated. Note: Both options depend on the LED status when component recognition is activated.

Understanding the LED indicators on the Sensor Module Cabinet-Mounted SMC20 is crucial for efficiently operating and maintaining your Sinamics S120 AC Drive system. With this knowledge, you can quickly identify and rectify any issues, ensuring your drive system operates smoothly and effectively.

For more detailed information about the cause of faults and how they can be rectified, refer to the SINAMICS S120 Commissioning Manual (IH1) and the SINAMICS S120/S150 List Manual (LH1).