import logging
import re
from ctypes import c_ushort
from dsmr_parser.objects import MBusObject, CosemObject, ProfileGenericObject
from dsmr_parser.exceptions import ParseError, InvalidChecksumError
logger = logging.getLogger(__name__)
class TelegramParser(object):
def __init__(self, telegram_specification, apply_checksum_validation=True):
"""
:param telegram_specification: determines how the telegram is parsed
:param apply_checksum_validation: validate checksum if applicable for
telegram DSMR version (v4 and up).
:type telegram_specification: dict
"""
self.telegram_specification = telegram_specification
self.apply_checksum_validation = apply_checksum_validation
def parse(self, telegram_data):
"""
Parse telegram from string to dict.
The telegram str type makes python 2.x integration easier.
:param str telegram_data: full telegram from start ('/') to checksum
('!ABCD') including line endings in between the telegram's lines
:rtype: dict
:returns: Shortened example:
{
..
r'\d-\d:96\.1\.1.+?\r\n': <CosemObject>, # EQUIPMENT_IDENTIFIER
r'\d-\d:1\.8\.1.+?\r\n': <CosemObject>, # ELECTRICITY_USED_TARIFF_1
r'\d-\d:24\.3\.0.+?\r\n.+?\r\n': <MBusObject>, # GAS_METER_READING
..
}
:raises ParseError:
:raises InvalidChecksumError:
"""
if self.apply_checksum_validation \
and self.telegram_specification['checksum_support']:
self.validate_checksum(telegram_data)
telegram = {}
for signature, parser in self.telegram_specification['objects'].items():
match = re.search(signature, telegram_data, re.DOTALL)
# Some signatures are optional and may not be present,
# so only parse lines that match
if match:
telegram[signature] = parser.parse(match.group(0))
return telegram
@staticmethod
def validate_checksum(telegram):
"""
:param str telegram:
:raises ParseError:
:raises InvalidChecksumError:
"""
# Extract the part for which the checksum applies.
checksum_contents = re.search(r'\/.+\!', telegram, re.DOTALL)
# Extract the hexadecimal checksum value itself.
# The line ending '\r\n' for the checksum line can be ignored.
checksum_hex = re.search(r'((?<=\!)[0-9A-Z]{4})+', telegram)
if not checksum_contents or not checksum_hex:
raise ParseError(
'Failed to perform CRC validation because the telegram is '
'incomplete. The checksum and/or content values are missing.'
)
calculated_crc = TelegramParser.crc16(checksum_contents.group(0))
expected_crc = int(checksum_hex.group(0), base=16)
if calculated_crc != expected_crc:
raise InvalidChecksumError(
"Invalid telegram. The CRC checksum '{}' does not match the "
"expected '{}'".format(
calculated_crc,
expected_crc
)
)
@staticmethod
def crc16(telegram):
crc16_tab = []
for i in range(0, 256):
crc = c_ushort(i).value
for j in range(0, 8):
if (crc & 0x0001):
crc = c_ushort(crc >> 1).value ^ 0xA001
else:
crc = c_ushort(crc >> 1).value
crc16_tab.append(hex(crc))
crcValue = 0x0000
for c in telegram:
d = ord(c)
tmp = crcValue ^ d
rotated = c_ushort(crcValue >> 8).value
crcValue = rotated ^ int(crc16_tab[(tmp & 0x00ff)], 0)
return crcValue
class DSMRObjectParser(object):
"""
Parses an object (can also be see as a 'line') from a telegram.
"""
def __init__(self, *value_formats):
self.value_formats = value_formats
def _is_line_wellformed(self, line, values):
# allows overriding by child class
return (values and (len(values) == len(self.value_formats)))
def _parse_values(self, values):
# allows overriding by child class
return [self.value_formats[i].parse(value)
for i, value in enumerate(values)]
def _parse(self, line):
# Match value groups, but exclude the parentheses
pattern = re.compile(r'((?<=\()[0-9a-zA-Z\.\*\-\:]{0,}(?=\)))')
values = re.findall(pattern, line)
if not self._is_line_wellformed(line, values):
raise ParseError("Invalid '%s' line for '%s'", line, self)
# Convert empty value groups to None for clarity.
values = [None if value == '' else value for value in values]
return self._parse_values(values)
class MBusParser(DSMRObjectParser):
"""
Gas meter value parser.
These are lines with a timestamp and gas meter value.
Line format:
'ID (TST) (Mv1*U1)'
1 2 3 4
1) OBIS Reduced ID-code
2) Time Stamp (TST) of capture time of measurement value
3) Measurement value 1 (most recent entry of buffer attribute without unit)
4) Unit of measurement values (Unit of capture objects attribute)
"""
def parse(self, line):
return MBusObject(self._parse(line))
class CosemParser(DSMRObjectParser):
"""
Cosem object parser.
These are data objects with a single value that optionally have a unit of
measurement.
Line format:
ID (Mv*U)
1 23 45
1) OBIS Reduced ID-code
2) Separator "(", ASCII 28h
3) COSEM object attribute value
4) Unit of measurement values (Unit of capture objects attribute) - only if
applicable
5) Separator ")", ASCII 29h
"""
def parse(self, line):
return CosemObject(self._parse(line))
class ProfileGenericParser(DSMRObjectParser):
"""
Power failure log parser.
These are data objects with multiple repeating groups of values.
Line format:
ID (z) (ID1) (TST) (Bv1*U1) (TST) (Bvz*Uz)
1 2 3 4 5 6 7 8 9
1) OBIS Reduced ID-code
2) Number of values z (max 10).
3) Identifications of buffer values (OBIS Reduced ID codes of capture objects attribute)
4) Time Stamp (TST) of power failure end time
5) Buffer value 1 (most recent entry of buffer attribute without unit)
6) Unit of buffer values (Unit of capture objects attribute)
7) Time Stamp (TST) of power failure end time
8) Buffer value 2 (oldest entry of buffer attribute without unit)
9) Unit of buffer values (Unit of capture objects attribute)
"""
def __init__(self, buffer_types, head_parsers, parsers_for_unidentified):
self.value_formats = head_parsers
self.buffer_types = buffer_types
self.parsers_for_unidentified = parsers_for_unidentified
def _is_line_wellformed(self, line, values):
if values and (len(values) >= 2) and (values[0].isdigit()):
buffer_length = int(values[0])
return (buffer_length <= 10) and (len(values) == (buffer_length * 2 + 2))
else:
return False
def _parse_values(self, values):
buffer_length = int(values[0])
buffer_value_obis_ID = values[1]
if (buffer_length > 0):
if buffer_value_obis_ID in self.buffer_types:
bufferValueParsers = self.buffer_types[buffer_value_obis_ID]
else:
bufferValueParsers = self.parsers_for_unidentified
# add the parsers for the encountered value type z times
for _ in range(buffer_length):
self.value_formats.extend(bufferValueParsers)
return [self.value_formats[i].parse(value) for i, value in enumerate(values)]
def parse(self, line):
return ProfileGenericObject(self._parse(line))
class ValueParser(object):
"""
Parses a single value from DSMRObject's.
Example with coerce_type being int:
(002*A) becomes {'value': 1, 'unit': 'A'}
Example with coerce_type being str:
(42) becomes {'value': '42', 'unit': None}
"""
def __init__(self, coerce_type):
self.coerce_type = coerce_type
def parse(self, value):
unit_of_measurement = None
if value and '*' in value:
value, unit_of_measurement = value.split('*')
# A value group is not required to have a value, and then coercing does
# not apply.
value = self.coerce_type(value) if value is not None else value
return {
'value': value,
'unit': unit_of_measurement
}
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