Python-сообщество

 import crcmod
#
def crc16_calc(chunk): # считает crc16
    crc16 = crcmod.mkCrcFun(0x18005, initCrc=0xFFFF, rev=True, xorOut=0x0000)
    crc_int = crc16(chunk)
    high_byte = crc_int >> 8
    low_byte = crc_int & 0xff
    out_hex = '{:02X}{:02X}'.format(low_byte, high_byte)
    return bytes.fromhex(out_hex)
#
def create_package(addr, f, l, mask_ch, id) -> bytes: # собирает пакет
    hex_chunk = '{:08d}{:02X}{:02X}{:<08}{:02X}'.format(addr, f, l, '{:02X}'.format(mask_ch), id)
    chunk = bytes.fromhex(hex_chunk)
    data = chunk + crc16_calc(chunk)
    return data
#
addr = 12345678 # - сетевой адрес устройства (4байта) в формате BCD, старшим байтом вперёд
f = 1 # - код функции запроса (1 байт) чтение текущих показаний
l = 14 # - общая длина пакета (1 байт) 
mask_ch = 2 # – битовая маска запрашиваемых каналов (4 байта) (чтение второго канала)
id = 24228 # - идентификатор запроса (любые 2 байта)
#
data = create_package(addr, f, l, mask_ch, id) # отправить теплосчетчику,
#
print(data) #b'\x124Vx\x01\x0e\x02\x00\x00\x00^\xa4Ac'

  
>>> def get_data():
...     text = '085616180112a3e8103c0000000001005fab'
...     out = bytes.fromhex(text)
...     return out
... 
>>> def parse_data(data):
...     addr = data[:4]
...     func = data[4:5]
...     code = data[5:6]
...     payload = data[6:-4]
...     ident = data[-4:-2]
...     crc = data[-2:]
...     out = (
...         addr,
...         func,
...         code,
...         payload,
...         ident,
...         crc
...     )
...     return out
... 
>>> data = get_data()
>>> 
>>> data_parsed = parse_data(data)
>>> print(data_parsed)
(b'\x08V\x16\x18', b'\x01', b'\x12', b'\xa3\xe8\x10<\x00\x00\x00\x00', b'\x01\x00', b'_\xab')
>>> 
>>> print(list(data_parsed[0]))
[8, 86, 22, 24]
>>> print(list(data_parsed[1]))
[1]
>>> print(list(data_parsed[2]))
[18]
>>> print(list(data_parsed[3]))
[163, 232, 16, 60, 0, 0, 0, 0]
>>> print(list(data_parsed[4]))
[1, 0]
>>> print(list(data_parsed[5]))
[95, 171]
>>>

  
>>> def get_data():
...     text = '085616180112a3e8103c0000000001005fab'
...     out = bytes.fromhex(text)
...     return out
... 
>>> def parse_data(data):
...     addr = data[:4]
...     func = data[4:5]
...     code = data[5:6]
...     payload = data[6:-4]
...     ident = data[-4:-2]
...     crc16 = data[-2:]
...     out = {
...         'address': addr,
...         'function': func,
...         'code': code,
...         'payload': payload,
...         'id': ident,
...         'crc': crc16
...     }
...     return out
... 
>>> data = get_data()
>>> 
>>> data_parsed = parse_data(data)
>>> print(data_parsed)
{'address': b'\x08V\x16\x18', 'function': b'\x01', 'code': b'\x12', 'payload': b'\xa3\xe8\x10<\x00\x00\x00\x00', 'id': b'\x01\x00', 'crc': b'_\xab'}
>>> 
>>> print(list(data_parsed['address']))
[8, 86, 22, 24]
>>> print(list(data_parsed['function']))
[1]
>>> print(list(data_parsed['code']))
[18]
>>> print(list(data_parsed['payload']))
[163, 232, 16, 60, 0, 0, 0, 0]
>>> print(list(data_parsed['id']))
[1, 0]
>>> print(list(data_parsed['crc']))
[95, 171]
>>>

  
>>> class Data:
...     def __init__(self, addr, func, code,
...                  payload, ident, crc16):
...         self._addr = addr
...         self._func = func
...         self._code = code
...         self._payload = payload
...         self._ident = ident
...         self._crc16 = crc16
...     def __str__(self):
...         t = (self._addr, self._func, self._code,
...              self._payload, self._ident, self._crc16)
...         return '{}{}'.format(__class__.__name__, t)
...     def addr(self):
...         return self._addr
...     def func(self):
...         return self._func
...     def code(self):
...         return self._code
...     def payload(self):
...         return self._payload
...     def ident(self):
...         return self._ident
...     def crc16(self):
...         return self._crc16
... 
>>> def get_data():
...     text = '085616180112a3e8103c0000000001005fab'
...     out = bytes.fromhex(text)
...     return out
... 
>>> def parse_data(data):
...     addr = data[:4]
...     func = data[4:5]
...     code = data[5:6]
...     payload = data[6:-4]
...     ident = data[-4:-2]
...     crc16 = data[-2:]
...     out = Data(
...         addr,
...         func,
...         code,
...         payload,
...         ident,
...         crc16
...     )
...     return out
... 
>>> data = get_data()
>>> 
>>> data_parsed = parse_data(data)
>>> print(data_parsed)
Data(b'\x08V\x16\x18', b'\x01', b'\x12', b'\xa3\xe8\x10<\x00\x00\x00\x00', b'\x01\x00', b'_\xab')
>>> 
>>> print(list(data_parsed.addr()))
[8, 86, 22, 24]
>>> print(list(data_parsed.func()))
[1]
>>> print(list(data_parsed.code()))
[18]
>>> print(list(data_parsed.payload()))
[163, 232, 16, 60, 0, 0, 0, 0]
>>> print(list(data_parsed.ident()))
[1, 0]
>>> print(list(data_parsed.crc16()))
[95, 171]
>>>

  
>>> data = bytes([0x01, 0x02, 0x03])
>>> data
b'\x01\x02\x03'
>>> 
>>> data[1]
2
>>> 
>>> data[1] = 4
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'bytes' object does not support item assignment
>>>

  
>>> data = bytearray([0x01, 0x02, 0x03])
>>> data
bytearray(b'\x01\x02\x03')
>>> 
>>> data[1]
2
>>> 
>>> data[1] = 4
>>> data
bytearray(b'\x01\x04\x03')
>>> 
>>> data[1]
4
>>>

  
import struct
 
def calculate_crc16_modbus(data):
    crc = 0xFFFF
    for byte in data:
        crc ^= byte
        for _ in range(8):
            if (crc & 0x0001):
                crc = (crc >> 1) ^ 0xA001
            else:
                crc >>= 1
    return crc.to_bytes(2, byteorder='little')
 
def parse(data):
    hex_data = bytes.fromhex(data)
    addr = hex_data[:4]
    f = hex_data[4]
    l = hex_data[5]
    ch = hex_data[6:-4]
    id = hex_data[-4:-2]
    crc = hex_data[-2:]
    if crc != calculate_crc16_modbus(hex_data[:-2]):
        print('bad data')
        return None
 
    out = {}
    out['addr'] = ''.join(f'{byte >> 4}{byte & 0x0F}' for byte in addr)
    out['func'] = int(f)
    out['len'] = int(l)
    out['value'] = out['func'] == 1 and struct.unpack('ff', ch)[0] or None
    out['id'] = id.hex()
    return out
 
data = parse('085616180112a3e8103c0000000001005fab')
print(f"addr: {data['addr']}")
print(f"func_num: {data['func']}")
print(f"byte_received: {data['len']}")
print(f"value: {data['value']}")
print(f"id: {data['id']}")