ABB A121 fault code meaning
ABB / A121
Series: DCS500B
Ext.Overvolt.Alarm
DC drive
Meaning:
Possible causes
Source: DCS500B Operation Manual Chinese edition (official site)
Series: DCS550
AutotuneFail
DC drive
Meaning: Autotuning failed
Possible causes
Source: DCS550 Manual (EN, official site)