100 lines
4.4 KiB
Python
100 lines
4.4 KiB
Python
# Декодирование UART-обмена ПМ35 с командами Modbus 03/06. Учитывается исторический ответ на
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# 128 слов с нулевым полем числа байтов; универсальный Modbus-parser без этого правила
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# потеряет границу сообщения.
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"""PM35 MODBUS 03/06, including the legacy 128-word/zero-byte-count reply."""
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from .set_uart import crc16, number
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def parse_pm35(raw, role):
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raw = bytes(raw)
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if len(raw) < 5:
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raise ValueError('Incomplete PM35 frame')
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if crc16(raw[:-2], True) != number(raw[-2:]):
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raise ValueError('PM35 CRC mismatch')
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address, function = raw[:2]
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result = dict(protocol='PM35', controller=address, function=function, raw=raw)
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if function in (0x83, 0x86):
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if len(raw) != 5 or role == 'request':
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raise ValueError('Invalid exception response')
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result['summary'] = 'PM35 node=%d exception fn=%02X code=%d' % (address, function, raw[2])
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elif function == 6 or function == 3 and role == 'request':
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if len(raw) != 8:
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raise ValueError('PM35 request/06 must contain 8 bytes')
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register, value = number(raw[2:4], 'big'), number(raw[4:6], 'big')
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if register >= 128 or function == 3 and not 1 <= value <= 128 - register:
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raise ValueError('PM35 register range outside 0..127')
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result.update(register=register, value=value)
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result['summary'] = 'PM35 node=%d %s R%d %s=%d' % (address,
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'READ' if function == 3 else 'WRITE/echo', register,
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'count' if function == 3 else 'value', value)
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if function == 6 and register == 127:
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result['summary'] += ' command_bits=%04X' % value
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elif function == 3:
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count = raw[2] or 256
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if count % 2 or len(raw) != count + 5:
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raise ValueError('Invalid PM35 response byte count')
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result['values'] = [number(raw[i:i+2], 'big') for i in range(3, len(raw)-2, 2)]
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result['summary'] = 'PM35 node=%d READ response %d words: %s' % (address,
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len(result['values']), ' '.join('%04X' % v for v in result['values']))
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else:
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raise ValueError('Unsupported PM35 function')
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return result
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class PM35Parser:
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def __init__(self, role):
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self.role = role
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self.buffer = []
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def flush(self):
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if not self.buffer:
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return []
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ss, es = self.buffer[0][1], self.buffer[-1][2]
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self.buffer = []
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return [(ss, es, None, 'Incomplete PM35 frame')]
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def feed(self, value, ss, es):
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self.buffer.append((value, ss, es))
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events = []
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while len(self.buffer) >= 3:
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raw = bytes(item[0] for item in self.buffer)
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fn = raw[1]
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if fn not in (3, 6, 0x83, 0x86):
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del self.buffer[0]
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continue
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role = self.role
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total = 5 if fn & 128 else 8
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if role == 'auto' and fn == 3:
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candidates = [(8, 'request'), ((raw[2] or 256) + 5, 'response')]
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found = None
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for length, candidate_role in candidates:
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if len(raw) >= length:
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try:
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found = (length, candidate_role, parse_pm35(raw[:length], candidate_role))
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break
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except ValueError:
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pass
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if found:
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length, candidate_role, result = found
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events.append((self.buffer[0][1], self.buffer[length-1][2], result, None))
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del self.buffer[:length]
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continue
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if len(raw) < max(length for length, _ in candidates):
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break
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events.append((self.buffer[0][1], self.buffer[-1][2], None, 'Invalid PM35 frame/CRC'))
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del self.buffer[0]
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continue
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if fn == 3 and role == 'response':
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total = (raw[2] or 256) + 5
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if len(raw) < total:
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break
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result, error = None, None
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try:
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result = parse_pm35(raw[:total], role)
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except ValueError as exc:
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error = str(exc)
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events.append((self.buffer[0][1], self.buffer[total-1][2], result, error))
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del self.buffer[:1 if error else total]
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return events
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