python access violation writing 0x00000000

I use two method call c interface:

c interface:

int sd_EnumDevice(char** szDevNames, ULONG *pulLen)
output:
szDevNames enum devices and return all devices name
pulLen return devices name length

my python code:

#1.
szDevNames = create_string_buffer(8)
type_p_int = create_string_buffer(10)
#2.
type_p_char = c_char_p()
type_p_long = c_ulong(0)

try:
    self.dll.sd_EnumDevice(type_p_char,type_p_long)
except Exception as e:
    print('', str(e))

Can anyone help me with this error?

exception: access violation writing 0x00000000