Setting up ZKTeco ZK8500 (ZK9500) fingerprint scanner in Python

Question

I am working on a Python project that includes using Images taken by Fingerprint scanner and processing them. I am currently using ZKTeco ZK8500(ZK9500) that is provided with C SDK library. But i have very little knowledge in C/C++ and to be honest Python is not my strongest language. I am trying to use C SDK via ctypes library in Python but i have some difficulties with that. I am currently testing on Windows, installed SDK from official site. So far my code looks like:

import ctypes
from ctypes import *
import logging

logging.basicConfig(filename='app_fp.log',
                    filemode='a',
                    format='%(asctime)s - %(levelname)s - %(message)s',
                    datefmt='%d-%m-%Y %H:%M:%S',
                    level=logging.INFO)

lib_3 = CDLL('libzkfp.dll')
###############################
lib_3.ZKFPM_Init.restype = ctypes.c_int

lib_3.ZKFPM_Terminate.restype = ctypes.c_int

lib_3.ZKFPM_GetDeviceCount.restype = ctypes.c_int

lib_3.ZKFPM_OpenDevice.restype = ctypes.c_void_p
lib_3.ZKFPM_OpenDevice.argtypes = [ctypes.c_int]

lib_3.ZKFPM_CloseDevice.restype = ctypes.c_int
lib_3.ZKFPM_CloseDevice.argtypes = [ctypes.c_void_p]

lib_3.ZKFPM_GetParameters.restype = ctypes.c_int
lib_3.ZKFPM_GetParameters.argtypes = [ctypes.c_void_p,
                                      ctypes.c_int,
                                      ctypes.POINTER(ctypes.c_ubyte),
                                      ctypes.POINTER(ctypes.c_uint),
                                      ]

paramChar = c_ubyte()
paramInt = c_uint()
################################

res_init = lib_3.ZKFPM_Init()
print("Init:", res_init)

res_getDeviceCount = lib_3.ZKFPM_GetDeviceCount()
print("Dev count:", res_getDeviceCount, type(res_getDeviceCount))

dev0_handle = lib_3.ZKFPM_OpenDevice(0)
print("Dev HANDLE:", dev0_handle)

dev0_getParam = lib_3.ZKFPM_GetParameters(dev0_handle,
                                          1102,
                                          byref(paramChar),
                                          byref(paramInt))
print("Get dev name:", dev0_getParam, paramChar, sizeof(paramChar))

logging.info("DeviceHandle:" + str(dev0_handle))


res_close = lib_3.ZKFPM_CloseDevice(dev0_handle)
print("Close dev:", dev0_handle, res_close)
#
res_terminate = lib_3.ZKFPM_Terminate()
print("Terminate:", res_terminate)

Stdout looks like this:

Init: 0
Dev count: 2 <class 'int'>
Dev HANDLE: 2682398313632
Get dev name: -3 c_ubyte(0) 1
Close dev: 2682398313632 0
Terminate: 0
Check sum data is true!sum=9286, buf[val]=9286
Check sum data is true!sum=-44, buf[val]=-44
opts->Stripe_Reference_Point_X=654, opts->Stripe_Reference_Point_Y=542
Check sum data is true!sum=908, buf[val]=908
CMOS Sensor->Exposure:256, RedGain:152, GreenGain1:200, GreenGain2:187,BlueGain:112.
Main1LED:200, Main2LED:200, Side1LED:175, Side2LED:175, Anti1LED:200, Anti2LED:200.
start to set the exposure parameters

Process finished with exit code 0

Description of GetParameters function from SDK is:

5.2.7 ZKFPM_GetParameters
[Function]
int APICALL ZKFPM_GetParameters(HANDLE hDevice, int nParamCode, unsigned
char* paramValue, unsigned int* cbParamValue);
[Purpose]
This function is used to acquire fingerprint reader parameters.
[Parameter Description]
hDevice
Device operation instance handle
nParamCode
Parameter code (For details, see the parameter code list.)
paramValue [out]
Returned parameter value
cbParamValue [in/out]
[in] Memory size allocated based on nParamCode
[out]Data size of the returned parameter value
[Return Value] 
 0 Succeeded
Others Failed (See the Appendixes.)

Questions:

1. I do not understand why i can OpenDevice, can CloseDevice but get Get dev name: -3 c_ubyte(0) 1 when i try to get parameter i get -3- No device connected. Maybe something in my Python declaration or variable types?
2. How i can get image to file from fingerprint scanner? Code snippets if anybody knows?