pysml

Decoder library for SML (Smart Meter Language)

What and why

Goal of this project is to create a compact python library for decoding SML output from a electric power meter or at least for the one which I am using (the EMH ED300L).

Side goal is to improve my personal skills in python programming.

References Hardware

• Volkszaehler::Hardware
• Weidmann::IR Schreib/Lesekopf USB (Optokopf)
• German Metering OP-210

References Software

From Volkszaehler::Software

• libsml
• SMLlib

References Protocol

• Technische Richtlinie BSI TR-03109-1 - the main specification
• DLMS blue book - contains OBIS codes and measurement units
• EDI@Energy Codeliste der OBIS-Kennzahlen für den deutschen Energiemarkt
• Beschreibung SML Datenprotokoll für SMART METER

On OBIS codes from DLMS blue book

• An OBIS code consists of 6 octets A B C D E F
• section 6 / 6.3.2 / 7.2.1: general structure
• section 7.5: A = 1: Electricity
  • section 7.5.1: C = 1: Active Power +
  • section 7.5.1: C = 2: Active Power -
  • section 7.5.2.1: D = 8: Time Integral 1
  • section 7.5.3.2: E = 0: Total
  • section 7.5.3.2: E = 1: Rate 1
  • section 7.5.3.2: E = 2: Rate 2

References Protocol Analyis

• Stefan Weigert - great approach, Python script
• msxfaq.de 1
• msxfaq.de 2
• volkszaehler.org
• schatenseite.de
• kabza.de

ED300L specific Links

• EMH ED300L
• Data Sheet
• User Manual
• Produkthandbuch - section 5.3 contains list of data sets
• Another list of the parameters

Simple Test: readout data with Linux command line

After plugging, the Weidmann Lesekopf is available as /dev/ttyUSB0

First set the device to 9600 bit/s, raw mode. In particular the raw mode is important!

• stty -F /dev/ttyUSB0 9600
• stty -F /dev/ttyUSB0 raw

Now read out the data and pipe through hexdump for nice formatting

• cat /dev/ttyUSB0 | hexdump -e '16/1 "%02x " "\n"'

Or store it directly in a binary file for later analysis

• cat /dev/ttyUSB0 > edl300_raw.bin

Own software - requirements

• Python - portable between Windows/Linux/Raspberry Pi
• Simple - no full SML decoder to reduce complexity
• Robust - even if the ED300L specific format is assumed: implement saninty checks (expected values, crc)