Hi @milad, is the STO input linked to 0xC7 in the UART? I've done the below and it doesn't seem to toggle when applying 5V at the STO input.

Added this to SOLOMotorControllersUart.py

    #@brief  This command reads the values of the Drive Enable register 
    #          .The method refers to the Uart command: 0xC7
    def get_drive_enable(self) -> list:
        cmd = [self._address, ConstantUart.ReadDriveEnable,
               0x00, 0x00, 0x00, 0x00]
        result, error = self.__exec_cmd(cmd)
        if (result):
            data = get_data(cmd)
            return convert_from_data(data, DATA_TYPE.UINT32), ERROR.NO_ERROR_DETECTED
        else:
            return -1, error

Added this to ConstantUart.py

ReadDriveEnable = 0xC7

And this is my test code:

import SoloPy as solo

# set up comms and control parameters
mySolo = solo.SoloMotorControllerUart("COM3")
mySolo.set_motor_direction(solo.DIRECTION.COUNTERCLOCKWISE)
mySolo.set_control_mode(solo.CONTROL_MODE.TORQUE_MODE)

# initialise commands and recording 
set_torque_ref = 0
mySolo.set_torque_reference_iq(set_torque_ref)

while True:
    drive_state, error = mySolo.get_drive_enable()
    print(drive_state)

The test code just outputs 1 regardless of what STO is up to.