Move the X or Z axes of the CNC lathe machine under the Jog mode, the both AC servo drivers will be alarm for Err12 simultaneously.
Normally if one of the AC servo driver has problem, it would not caused two drivers alarm the same Err12.
1- Are the parameter setting of the AC servo motors and drivers proper?
2- Are the CNC parameter on the CNC controller correct?
3- Measure the insulting property of the two AC servo motors.
4- Check wiring of the X and Z drivers.
In this case we finally found the feedback cables of the X axis motor is in exchange with the Z axis motor, which caused the problem, correct the wiring then the alarm cleared and machine resumed.