DL/T645

Main implementation of DL/T645 protocol and utilities

Usage:

import serial
import dlt645


ser = serial.Serial(
    "/dev/ttyUSB0",
    baudrate=1200,
    bytesize=serial.EIGHTBITS,
    parity=serial.PARITY_EVEN,
    stopbits=serial.STOPBITS_ONE,
    timeout=1
)

station_addr = dlt645.get_addr(ser)

# requesting active energy
frame = dlt645.Frame(station_addr)
frame.data = "00000000"
ser.write(frame.dump())
framedata = dlt645.read_frame(dlt645.iogen(ser))
# the data will be the full payload (energy valu and data identification)
print(framedata.data)

# shorthand function to directly get the active energy value
dlt645.get_active_energy(station_addr, ser)
dlt645.iogen(flo)

Simple data generator for a file-like object, returns bytes one by one.

Parameters

flo – a file-like object instance

dlt645.read_frame(readgen)

Read a frame from a data generator, return a Frame instance.

Parameters

readgen (generator) – a generator returning data one byte at a time

dlt645.write_frame(flo, frame, awaken=True)

Write a frame to byte form to be written on a data line

Parameters

  • flo – a file-like object instance

  • frame (dlt645.Frame) – a Frame instance

  • awaken (bool) – whether to prefix the message with wake up bytes

class dlt645.Frame(addr=None, control=None)

DL/T645 frame representation with mechanisms to load/dump a frame from/into a data byte string.

Parameters

  • addr (str) – station address

  • control (dict) – a constrol code representation

compat

Protocol compatibitilty

frame

Raw frame data

data

data portion of a frame

addr

Station address

control

Structure representing the control code portion of a frame in a more human readable way

load(framedata)

Load a payload into a frame.

Parameters

framedata (bytearray) – a byte-like object holding a payload

dump()

Dump a frame as a byte-like object.

property checksum

Frame checksum

is_valid(cs=None)

Checksum validation

Parameters

cs – checksum byte

dlt645.checksum(data)

Return the checksum of a byte-like object

Parameters

data (bytearray) – a byte-like object containing data to use for the checksum

dlt645.bytetostr(bdata)

Convert a byte-like object to a string

Parameters

bdata (bytearray) – a byte-like payload

dlt645.load_addr(data)

Read an address from a byte-like object, return a byte-like object representing the address.

Parameters

data (bytearray) – a byte-like payload

dlt645.dump_addr(addr)

Dump an address to a byte-like object.

Parameters

addr (str) – a station address

dlt645.load_ctrl(data)

Read control code information, return a dict structure representing the different control code parts.

Parameters

data (bytearray) – a byte-like payload

dlt645.dump_ctrl(control)

Dump a control code representation to a byte-like object.

Parameters

control (dict) – a control code representation

dlt645.load_data(data)

Read data information, return a byte-like structure representing the data.

Parameters

data (bytearray) – a byte-like payload

dlt645.dump_data(data)

Dump a data payload to a byte-like object.

Parameters

data (str) – a data payload

dlt645.get_addr(flo, r_flo=None)

Utility function to read a station’s address, returns the address.

Parameters

  • flo – a file-like object instance for write

  • r_flo – a file-like object instance for read

dlt645.get_active_energy(addr, flo, r_flo=None)

Utility function to directly read active energy field, returns the energy value in kWh.

A file-like object is required for the communication, if ‘r_flo’ is None then ‘flo’ will be used for both read and write. This is useful when using a socketserver.StreamRequestHandler that provides different file-like objects for read and write.

Parameters

  • addr (str) – a station address

  • flo – a file-like object instance for write

  • r_flo – a file-like object instance for read