import time
from serial import Serial
import colorama
import struct
from colorama import Fore, Style
from typing import Sequence, Union
from binascii import b2a_hex
DEFAULT_MB_CRC_TABLE = (
00000, 49345, 49537, 320, 49921, 960, 640, 49729, 50689, 1728, 1920,
51009, 1280, 50625, 50305, 1088, 52225, 3264, 3456, 52545, 3840, 53185,
52865, 3648, 2560, 51905, 52097, 2880, 51457, 2496, 2176, 51265, 55297,
6_336, 6528, 55617, 6912, 56257, 55937, 6720, 7680, 57025, 57217, 8000,
56577, 7616, 7296, 56385, 5120, 54465, 54657, 5440, 55041, 6080, 5760,
54849, 53761, 4800, 4992, 54081, 4352, 53697, 53377, 4160, 61441, 12480,
12672, 61761, 13056, 62401, 62081, 12864, 13824, 63169, 63361, 14144, 62721,
13760, 13440, 62529, 15360, 64705, 64897, 15680, 65281, 16320, 16000, 65089,
64001, 15040, 15232, 64321, 14592, 63937, 63617, 14400, 10240, 59585, 59777,
10560, 60161, 11200, 10880, 59969, 60929, 11968, 12160, 61249, 11520, 60865,
60545, 11328, 58369, 9408, 9600, 58689, 9984, 59329, 59009, 9792, 8704,
58049, 58241, 9024, 57601, 8640, 8320, 57409, 40961, 24768, 24960, 41281,
25344, 41921, 41601, 25152, 26112, 42689, 42881, 26432, 42241, 26048, 25728,
42049, 27648, 44225, 44417, 27968, 44801, 28608, 28288, 44609, 43521, 27328,
27520, 43841, 26880, 43457, 43137, 26688, 30720, 47297, 47489, 31040, 47873,
31680, 31360, 47681, 48641, 32448, 32640, 48961, 32000, 48577, 48257, 31808,
46081, 29888, 30080, 46401, 30464, 47041, 46721, 30272, 29184, 45761, 45953,
29504, 45313, 29120, 28800, 45121, 20480, 37057, 37249, 20800, 37633, 21440,
21120, 37441, 38401, 22208, 22400, 38721, 21760, 38337, 38017, 21568, 39937,
23744, 23936, 40257, 24320, 40897, 40577, 24128, 23040, 39617, 39809, 23360,
39169, 22976, 22656, 38977, 34817, 18624, 18816, 35137, 19200, 35777, 35457,
19008, 19968, 36545, 36737, 20288, 36097, 19904, 19584, 35905, 17408, 33985,
34177, 17728, 34561, 18368, 18048, 34369, 33281, 17088, 17280, 33601, 16640,
33217, 32897, 16448)
class NoResponseError(IOError):
pass
class ChecksumError(IOError):
pass
class MBError(IOError):
pass
class ModbusMixin():
def print_hex(self, text: str, data: bytes):
print(text, *tuple(map(lambda x: '0x{:02X}'.format(x), (i for i in data))))
class Modbus(ModbusMixin):
# MB_CRC_TABLE: Sequence[int] = DEFAULT_MB_CRC_TABLE
MB_TIMEOUT: float = 0.05
MB_CRC_TABLE: Sequence[int] = DEFAULT_MB_CRC_TABLE
MB_DEBUG: bool = False
MB_TRIES: int = 3
def __init__(self, tty: str, brate: int, address: int):
self.serial = Serial(port=tty, baudrate=brate, timeout=0.05, parity='N', xonxoff=False)
self.address = address
@classmethod
def test(cls):
print(type(cls.MB_CRC_TABLE))
@classmethod
def _crc(cls, data: bytes) -> bytes:
crc = 0xFFFF
crc_table = cls.MB_CRC_TABLE
for char in data:
crc = (crc >> 8) ^ crc_table[(crc ^ char) & 0xFF]
return crc.to_bytes(2, 'little')
def raw_communicate(self, data: bytes, predicted_length:int = -1) -> bytes:
"""Send request and return it back with checksum"""
if self.MB_DEBUG:
self.print_hex('Request:', data)
self.serial.write(data)
response_bytes = bytearray()
start_time = time.time()
while True:
b = self.serial.read(1)
if len(b):
new_byte = bytearray(b)
response_bytes.extend(new_byte)
elif time.time() - start_time > self.MB_TIMEOUT:
break
if len(response_bytes) == predicted_length:
break
if self.MB_DEBUG:
self.print_hex('Responce:', response_bytes)
return response_bytes
def communicate(self, request: bytes, predicted_length: int = -1) -> bytes:
"""Send request and return rewponse after checksum check"""
pl = predicted_length + 2 if predicted_length != -1 else -1
response = self.raw_communicate(request + self._crc(request), pl)
if len(response) == 0:
raise NoResponseError('No response frome module')
crc_received = response[-2:]
crc_calculated = self._crc(response[:-2])
if crc_received != crc_calculated:
raise ChecksumError("CRC check dailed (got: 0x{}, calculated: 0x{})".format(
b2a_hex(crc_received).decode().upper(), b2a_hex(crc_calculated).decode().upper()))
return response
def mb_func(self, code: int, req: bytes, predicted_response_length: int = -1):
"""Call typical MB function with address and function code check,
return just response, no header and checksum included"""
error = None
for i in range(self.MB_TRIES):
try:
pl = predicted_response_length + 2 if predicted_response_length != -1 else -1
response = self.communicate(b''.join((self.address.to_bytes(1, 'big'),
code.to_bytes(1, 'big'), req)), pl)
if response[0] != self.address:
raise MBError("Modbus address mismatch in request and response ({}/{})".format(
self.address, response[0]))
elif response[1] != code:
raise MBError("Modbus function opcode mismatch in request and response ({}/{})".format(
code, response[1]))
return response[2:-2]
except (MBError, ChecksumError, NoResponseError) as e:
if self.MB_DEBUG:
print(e)
error = e
time.sleep(0.5)
raise error
def _read_registers(self, opcode: int, address: int, count: int, raw: bool = False) -> Union[Sequence[int], bytes]:
"""Read values of inpurt/holding registers from device"""
response = self.mb_func(opcode, address.to_bytes(2, 'big') + count.to_bytes(2, 'big'), 1 + 2*count)
try:
if raw:
return response[1:]
inp_count = response[0] // 2
return tuple(int.from_bytes(response[i:i + 2], 'big') for i in range(1, inp_count*2, 2))
except KeyError:
raise MBError("Incorrect response payload")
# 0x03
def read_holding_registers(self, address: int, count: int) -> Sequence[int]:
return self._read_registers(3, address, count)
def read_holding_registers_raw(self, address: int, count: int) -> bytes:
return self._read_registers(3, address, count, True)
def read_uint32_holding(self, address: int) -> int:
"""Read 32-bit integer from holding registers"""
return struct.unpack('>I', self.read_holding_registers_raw(address, 2))[0]
# 0x10
def write_holding_registers_raw(self, address:int, values: bytes):
"""Write 16-bit integers to holding registers on device"""
request = bytearray(address.to_bytes(2, 'big'))
request += (len(values) // 2).to_bytes(2, 'big')
request += len(values).to_bytes(1, 'big')
request += values
response = self.mb_func(16, bytes(request), 4)
if request[:4] != response:
raise MBError('Incorrect response payload')
#
def write_holding_register(self, address: int, value: int):
"""Write 16-bit integer to register on device"""
request = address.to_bytes(2, 'big') + value.to_bytes(2, 'big')
response = self.mb_func(6, request, len(request))
if request != response:
raise MBError('Incorrect response payload')
def write_uint32(self, address: int, value: int):
"""Write 32-bit integer to holding register"""
self.write_holding_registers_raw(address, struct.pack('>I', value))
def test_send(self, data: bytes):
while True:
self.serial.write(data)
time.sleep(1)
def send_recv(self, data, number):
self.serial.write(data)
# while True:
# self.serial.write(data)
# recv = self.serial.read_all()
# print(recv)
# print(recv.decode('utf_8'))
# time.sleep(1)
def main():
ADDR = 1
colorama.init()
dev = Modbus('COM22', 115200, ADDR)
# print(dev.read_holding_registers(0x0100, 1))
# print(dev.read_uint32_holding(0x0100))
# time.sleep(1)
if __name__ == '__main__':
main()