Siemens · SINAMICS G120
The drive has failed to receive setpoint values via the USS (Universal Serial Interface) communication protocol within the configured telegram off time. This suggests a problem with the USS master device or the communication settings, causing the drive to lose its operational commands and halt controlled operation.
Click steps to track your progress.
1. Inspect RS485 wiring on terminals X300 (A/B/common) for correct polarity, secure connections, and shield grounding.
2. Confirm that drive parameters P2010 (Baud rate), P2011 (USS address), and P2013 (Telegram off time) precisely match the USS master settings.
3. Use a multimeter to check for correct RS485 bus voltage levels (differential signal) at the drive terminals when the master is transmitting.
4. Increase the drive's P2013 (USS telegram off time) to 250ms to account for potential communication delays and retest.
5. Verify that RS485 bus termination (P2015 bit 0 for internal termination) is correctly configured, typically active at both physical ends of the bus.