17.
1 DLMS/COSEM
Introduction
IEC 62056 is a set of standards for electricity metering data exchange by theInternational Electrotechnical
Commission.
The IEC 62056 standards are the international standard versions of the DLMS/COSEM specification.
DLMS or Device Language Message Specification (originally Distribution Line Message Specification),[1] is the
suite of standards developed and maintained by the DLMS User Association (DLMS UA) and has been adopted by the
IEC TC13 WG14 into the IEC 62056 series of standards. The DLMS User Association maintains a D Type liaison with IEC
TC13 WG14 responsible for international standards for meter data exchange and establishing the IEC 62056 series. In
this role, the DLMS UA provides maintenance, registration and compliance certification services for IEC 62056
DLMS/COSEM.
COSEM or Companion Specification for Energy Metering, includes a set of specifications that defines
the transport and application layers of the DLMS protocol. The DLMS User Association defines the protocols into a set of
four specification documents namely Green Book, Yellow Book, Blue Book and White Book. The Blue Book describes the
COSEM meter object model and the OBIS object identification system, the Green Book describes the architecture and
protocols, the Yellow Book treats all the questions concerning conformance testing, and the White Book contains the
glossary of terms. If a product passes the conformance test specified in the Yellow Book, then a certification of
DLMS/COSEM compliance is issued by the DLMS UA.
The IEC TC13 WG14 groups the DLMS specifications under the common heading: "Electricity metering data exchange -
The DLMS/COSEM suite". DLMS/COSEM protocol is not specific to electricity metering, it is also used for gas, water and
heat metering.
Source: https://en.wikipedia.org/wiki/IEC_62056
DLMS Master
Overview
DLMS (Device Language Message Specification) is a suite of standards developed and maintained by the DLMS User
Association. COSEM (Companion Specification for Energy Metering) includes a set of specifications that define the
transport and application layers of the DLMS protocol.
In DLMS/COSEM all the data in electronic utility meters and devices are represented using mapping them to
appropriate classes and related attribute values.
Objects are identified with the help of OBIS (Object Identification System) codes (as per IEC 62056-61).
The DLMS driver allows only for readout and displaying only numeric values of DLMS object data fields. Connection via
TCP (HDLC or WRAPPER) or serial (RS232/RS485) ports are supported.
The setup of the DLMS driver consists of communication and tag configuration. Protocol-specific parameters (except
for DLMS/IEC handshake mode) apply for both serial and IP connections.
Configuration
Devices section
serial_number, physical_address and logical_address define the meter addressing parameters. Either
serial_number (meter serial number) or a combination of physical_address and logical_address is used. If a serial
number is provided, physical and logical server addresses are ignored.
Before configuring the Device section it is best to first check the connection parameters with a 3rd party DLMS
utility.
client_address is defined in hex and usually depends on the authentication used. Most meters support hex 11 for no
authentication.
type defines the object referencing. SN should be used for short name referencing and LN for logical name
referencing.
mode defines the communications mode. If IEC is used along with comms settings for serial readout, the connection is
initiated as per IEC 62056-21, at the default initial baud rate (300 7E1). DLMS-HDLC shall be used for HDLC
connections via IP. DLMS-WRAPPER is also supported for IP connections. The default setting is DLMS-HDLC.
timeout_ms defines the reply timeout for telegrams both via serial and TCP.
auth and password define the authentication mode and password. This can be set to None, or other authentication
variant (see table below), depending on the mode configured and supported by the particular meter.
ip and port define the IP address and TCP port for DLMS communication via IP.
Connection parameters are device-specific and can differ between makes, models and utility companies. For
initial connection settings please refer to the configuration of the particular meter.
When ip and port are configured, any serial port settings are ignored and the connection is initiated only via IP.
Device configuration parameters for DLMS meters acquisition:
Required Range
Default
Parameter Type Description Value
(when not
specified)
TCP RTU Min Max
name string User-friendly name for a device Yes Yes
description string Description of a device No No
device_alias string Alphanumeric string to identify a device Yes Yes
enable boolean Enabling/disabling of a device No No 1 0 1
protocol string Protocol to be used Yes Yes DLMS
serial_number integer Meter serial number No No 0
physical_address integer Meter's physical server address No No 1600
logical_address integer Meter logical server address No No 0
address_size integer Meter address size in bytes No No 1 1 4
client_address integer Client address Yes Yes
Meter object referencing: SN - short
type string No No SN SN, LN
referencing, LN - logical referencing
DLMS-‐ IEC, DLMS, DLMS-HDLC or
mode string Initial handshake mode. No No
HDLC DLMS-WRAPPER
timeout_ms integer Timeout in milliseconds No No 2500
None, Low, High, HighMd5,
auth string Authentication. No No None HighSha1, HighSha256,
HighGmac, HighEcdsa
No No
(when (when
password string Password for authentication
auth is auth is
None) None)
ip string IP address Yes -
port integer TCP port Yes -
device Communication port - Yes PORT1 PORT2
300, 600, 1200, 2400, 4800,
baudrate integer Communication speed (bauds/s) - No 9600 9600, 19200, 38400, 57600,
115200
databits integer Data bit count for communication - No 8 6 9
stopbits integer Stop bit count for communication - No 1 1 2
parity string Communication parity option - No none none, even, odd
Communication device flow control
flowcontrol string - No none none
option.
Number of requests, before the link is
considered lost (device status signals are
retry_counter integer No No 3
changed) and reconnect attempt will be
issued
If provided and positive all reads and
scan_rate_ms integer writes will be executed within the No No 10000
timeframe in milliseconds
Defines how often (in milliseconds) the
client will try to reestablish
reconnect_time integer No No 1000
communication with the meter after an
unsuccessful attempt.
Signals section
DLMS configuration parameters creating signals:
Required Range
Default
Parameter Type Description Value
(when not
specified)
TCP RTU Min Max
signal_name string User-friendly signal name Yes Yes
device_alias string Device alias from a Devices tab Yes Yes
Unique alphanumeric name of the signal to
signal_alias string Yes Yes
be used
enable boolean Enabling/disabling of an individual signal No No 1 0 1
log boolean Enable logging in the event log No No 0 0 1
short_name integer Address of value to read (Short name). No No 0
OBIS codes can be accompanied by an
attribute index, eg.: 1.0.1.8.0.255:2.
Objects of register and extended register
obis_job string types do not require indexes and the Yes Yes
scalers are applied to values automatically
(though they can still be used if attributes
other than the value need to be read out).
Debugging the DLMS service
If the configuration for DLMS devices is set up, the handler for the protocol will start automatically. If the configuration
is missing or contains errors, the protocol will not start. It is done intentionally to decrease unnecessary memory
usage.
If DLMS does not work properly (e.g. no communication between devices, data is corrupted, etc.), a user can launch a
debug session from the command-line interface and find out why the link is not functioning properly. To launch a
debugging session, a user should stop the dlms process and run the dlms command with respective flags as in the
table shown below.
Procedure for DLMS protocol service debugging:
Step 1: Service must be stopped by entering the following command into the WCC Lite:
/etc/init.d/dlms stop
Step 2: After service is stopped it must be started with the preferred configuration file (JSON files found in
/etc/dlms folder) and a debug level 7: dlms -c /etc/dlms/dlms.json -d7 --dlms
Additional output forming options described in the table below.
Step 3: Once the problem is diagnosed normal operations can be resumed with the following
command: /etc/init.d/dlms start
DLMS command line debugging options
Option Description
-h [ –-help ] Display help information
-V [ –-version ] Show version
-p [ -–port ] Show output for one port only
-d <debug level> Set debugging level
-c [ –-config ] Config path
Revision #3
Created 26 January 2024 13:13:06 by Gabriele
Updated 13 November 2024 06:46:27 by Andrej
