The dynamixel is now working fine !

the issue was : -12V 2A supply better than 1A to make sure you cover the current consumption of the dynamixel servo motor (900mA), the Dynamixel L0 base board and Driver Shield and the Luos Gate (communication to PC)

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/eaf0b58c-0821-4d22-83d9-5ea6d68aaa85/ax-12A_setup_Hints__PyLuos_fun_or_variable_to_turn_dynamixel__.jpg

Luos_Gate_and_Dynamixel_control.ipynb

Luos_Gate_EstablishConnectionWithLaptop.py