DLMS/COSEM communication protocol

Supported device types and versions
Communication line configuration
Station configuration
Station parameters
Settings of transmission parameters
I/O tag configuration
I/O tag address
Literature
Changes and modifications
Document revisions

Supported device types and versions

This protocol executes a serial communication with the devices by binary HDLC protocol according to DLMS/COSEM standard.
It supports only so-called "Short Name (SN) referencing" addressing of I/O tags.

Devices under test:

• EMH LZQJ
• Landis ZMD400

Communication line configuration

• Supported line categories: Serial, SerialOverUDP Device Redundant, MODEM.

Station configuration

• Communication protocol "DLMS/COSEM".

The station address (DLMS Server HDLC/MAC Address) consists of two parts: Upper MAC Address and Lower MAC Address. Each of them is in the range from 0 to 16383 (3FFFH).

As per a specification, DLMS UA 1000-2 Ed. 7.0 (Green Book) represents:

• Upper MAC Address is used for addressing a Logical Device, i.e. separately addressable entity within the physical device.
• Lower MAC Address is used for addressing of a Physical Device, i.e. multi-drop address on the line.

Upper MAC Address is required. An implicit value, which is set when missing the station address, is a reserved address Upper MAC Address = 1 (Management Logical Device).

In ordinary situations, when the physical device is identical with the logical one (one physical device = one logical device), you need not change this address. If the physical device integrates more logical devices, you should monitor the registry content "0-0:41.0.0" of "SAP assignment" class (class_id=17, attribute 2 "SAP_assignment_list") in the dialog box "DLMS SN Object List". This dialog box shows the list of logical devices that are integrated in the physical one.

This is the example of value representation of the attribute "SAP_assignment_list" of the class "SAP assignment" in the device which contains one logical devices with Upper MAC Address 16.
See also the protocol parameter "Client MAC address" and a document "DLMS UA 1000-2 Ed. 7.0", chapter 8.4.2.3 "Reserved special HDLC addresses".

Station parameters

Communication station configuration dialog box - Protocol parameters tab.
It influences some optional protocol parameters. The following station protocol parameters can be set:

Table 1

10:46:05.809 30-05-2011|D|DLMS> Z Detected: '4' = 4800 Bd

Settings of transmission parameters

Example 1 - line category Serial, the communication through IR optical head.

Example 2 - line category Serial, communication through IR optical head.

Example 3 - line category Serial, communication through RS232/RS485 interface.

I/O tag configuration

Possible I/O tag types: Ai, Ci, Di, TxtI, TiA, TiR.

I/O tag address

To understand the object addressing in DLMS/COSEM protocol, you should know so-called OBIS standard according to IEC 62056-61 Object Identification system (OBIS), Annex A - Code presentation.

The supported mode "Short Name (SN) referencing" does not use OBIS address but a numerical address in the range of 16 bits.

The individual data entities are presented in so-called COSEM objects (Companion Specification for Energy Metering), which are the instances of COSEM classes (COSEM interface classes, COSEM IC). The types of COSEM classes are specified in the document "COSEM Identification System and Interface Classes, Ed. 10.0", i.e. DLMS Blue Book. Each COSEM class has own identification number ("class_id") and the attributes with the sequence number. The attribute helps to get a specific parameter of given data entity.
Each instance has its initial address (base_name), which is also the address of the first attribute of class. "logical_name" is the first attribute of all COSEM classes. When reading this attribute, a user can obtain OBIS address of data entity that is presented by given class. The address of other attributes are calculated according to this formula:

short_name = base_name + ((attribute_index - 1) * 0x08)

The attributes can be static or dynamic depending on whether their value is static (i.e. unchanging, set by a producer or in configuration of device) or dynamic (changing). In D2000 System, we recommend to configure only the dynamic attributes because the own value of measured data entity is in dynamic attributes. If it is necessary, for the interpretation of value in dynamic attribute, other static or dynamic attributes can be read automatically. See more information in the section Supported COSEM clasess.

In the following tables you can find the supported COSEM classes. The attributes that represents own value of data entity (i.e. value that is important for a user) are characterized as "Yes, value of entity" in the column "Support in D2000". The static attributes are read automatically and characterized as "Automatically".

Supported COSEM classes

Historical data reading from loading profiles

The reading of historical data from loading profiles is made by the instances of COSEM classes "Profile generic" (class_id = 7), i.e. the configuration of I/O tag in attribute 2 ("buffer"). This I/O tag always contains the invalid valued in D2000 System but it enables to read a buffer of the instance of COSEM class "Profile generic".

Data about objects that are accessible by reading of attribute "capture_objects" are stored into buffer. D2000 System automatically searches I/O tags (its address paramters) that match the objects from attribute "capture_objects". The objects are searched by these parameters: "logical_name", "class_id" and "attribute_index".

TELL command GETOLDVAL or ESL action GETOLDVAL start the reading of all the configured loading profiles on the station. The time interval with data is always read by the parameters of TELL command or ESL action from the loading profile.

Supported value types of class attributes

I/O tag address - configuration dialog box

The following picture shows a configuration dialog box of I/O tag address.

The meaning of the parameters in dialog box:

DLMS SN Object List dialog box

If these conditions are fulfilled - the device is connected to D2000 System, a communication station exists and the device communicates, you can define the parameters of I/O tag address by the selection of the object from the list of all objects on the device. A special class "Association SN" with predefined address base_name 0xFA00 is intended for reading the list of objects. There is no need to configure any other I/O tags, just click on the button Select in Object list... .

First loading of the list takes several minutes depending on the baud rate. The window displays the information "Waiting for data...".

After data loading, the list of objects and their description will show in the window:

You can find the following information in the list:

• each row represents one instance of COSEM class,
• OBIS address of object follows the icon of class,
• then there is the information about SN address (base_name) of particular instance of COSEM class and about its type (class_id and version),
• when clicking on symbol (+) you can unhide the COSEM classes, which are supported in D2000 System.

When opening the main nod, the supported attributes of class will display:

The information about attribute includes:

• attribute index (attribute_index) - means a sequence number of attribute, it follows the icon,
• attribute name,
• static or dynamic attribute.

There can be next symbol (+) near the icon. When opening it and clicking on the row "Attribute value=", you can get the current value of attribute:

This feature enables fast browsing the attributes of all supported COSEM classes. The dialog window works as the Object List and Value Browser.

The bottom part of dialog box contains these checkboxes:

• Show hexadecimal - shows all the addresses of base_name classes as hex number or decimal one.
• Show inactive objects
• Show unsupported classes - enables to display the instances of unsupported COSEM classes.

To close the dialog box without any changes, click on Cancel button.

To insert the addressing parameters of attribute of instance into the address of I/O tag, double-click on the particular row. This closes the "DLMS SN Object List" dialog and the parameters will be set for the I/O tag.

OBIS address specification

The definition of OBIS address according to IEC 62056-61 is following:

• Value group A defines the energy type (0=abstract objects, 1=electricity, 7=gas),
• Value group B defines a channel number,
• Value group C defines a measured physical value,
• Value group D defines a type of processing,
• Value group E defines next processing or classification according to algorithm,
• Value group F defines storage of processed historical data.

Value group A up to F represents the integer number within the range from 0 up to 255.

For Value group C and D you can enter also the character values:

• character 'C' represents 96,
• character 'F' represents 97,
• character 'L' represents 98,
• character 'P' represents 99.

The address is written in  text format:

A-B:C.D.E*F

Value group C, D and E must always contains the value. Other blank values will be set on zero (0).

For more information see "List of standard OBIS codes and COSEM objects" on http://www.dlms.com, the document "List of standardized OBIS codes, DLMS UA, V2.3, (c) Copyright 1997-2005 DLMS User Association".

Literature

• DLMS User Association, COSEM Architecture and Protocols, Seventh Edition, (c) Copyright 1997-2009 DLMS User Association (Green book).
• DLMS User Association, COSEM Identification System and Interface Classes, Ed. 10.0, (c) Copyright 1997-2010 DLMS User Association (Blue book).
• International Standard IEC 62056-21, Direct Data Local Exchange, First edition 2002-05.
• International Standard IEC 62056-61, Object Identification System (OBIS), Second edition 2006-11.
• List of standardized OBIS codes, DLMS UA, V2.3, (c) Copyright 1997-2005 DLMS User Association.

Changes and modifications

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Document revisions

• Ver. 1.0 - May 30, 2011 - creating of document.