IEC 62056
Encyclopedia
DLMS or Device Language Message Specification (originally Distribution Line Message Specification), is the suite of standards developed and maintained by the DLMS User Association and has been co-opted by the IEC TC13 WG14 into the IEC 62056 series of standards.
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 three specification documents namely Green Book, Yellow Book and Blue Book.
The IEC TC13 WG 14 defines the DLMS specifications under the common heading: "Electricity metering - Data exchange for meter reading, tariff and load control."
to read utility meters. It is designed to operate over any media, including the Internet
. A meter sends ASCII
(in modes A..D) or HDLC (mode E) data to a nearby hand-held unit (HHU) using a serial port
. The physical media are usually either modulated light, sent with an LED
and received with a photodiode
, or a pair of wires, usually modulated by a 20mA current loop
. The protocol is usually half-duplex
.
The following exchange usually takes a second or two, and occurs when a person from the utility company presses a meter-reading gun against a transparent faceplate on the meter, or plugs into the metering bus at the mailbox of an apartment building.
The general protocol consists of a "sign on" sequence, in which a handheld unit identifies itself to the metering unit. During sign-on, the handheld unit addresses a particular meter by number. The meter and hand-held unit negotiate various parameters such as the maximum frame length during transmission and reception,Whether multiple frames can be sent without acknowledging individual frames(Windowing), the fastest communication rate that they can both manage(only in case of mode E switching to HDLC) etc.
Next the meter informs the hand held unit about the various parameters that are available with it in various security settings viz. the 'no security logical group', ' the low security logical groups' and ' the high security logical groups'.
If the parameter required is in no security group, just a get.request will provide the HHU with the desired response. If the parameter required is in low security group, a password authentication of the HHU is required before information can be read.
In case of high security parameters,the meter challenges the hand held unit with a cryptographic password. The hand held unit must return an encrypted password. If the password exchange is ok, the meter accepts the hand held unit- it is "signed on."
After signing on, the hand held unit generally reads a meter description. This describes some registers that describe the current count of metered units (i.e. kilowatt hours, megajoules, litres of gas or water) and the metering unit's reliability (is it still operating ok?). Occasionally a manufacturer will invent a new quantity to measure, and in this case, a new or different data type will appear in the meter definition. Most metering units have special modes for calibration and resetting meter registers. These modes are usually protected by anti-tampering features such as switches that sense if the meter enclosure has been opened.
The HHU may also be given limited rights to set or reset certain parameters in the meter.
The hand held unit then sends a sign-off message, and the meter automatically signs off after a previously negotiated time interval after the last message, if no sign-off message is sent.
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 three specification documents namely Green Book, Yellow Book and Blue Book.
The IEC TC13 WG 14 defines the DLMS specifications under the common heading: "Electricity metering - Data exchange for meter reading, tariff and load control."
- IEC 62056-21: Direct local data exchange (3d edition of IEC 61107) describes how to use COSEM over a local port (optical or current loop)
- IEC 62056-42: Physical layer services and procedures for connection-oriented asynchronous data exchange
- IEC 62056-46: Data link layer using HDLC protocol
- IEC 62056-47: COSEM transport layers for IPv4 networks
- IEC 62056-53: COSEM Application layer
- IEC 62056-61: Object identification system (OBIS)
- IEC 62056-62: Interface classes
Interface classes
In DLMS/COSEM, all the data in electronic meters and devices are represented by means of attribute values. Any real world thing can be described by attributes; methods allow operations to be performed on the attributes. Attributes and methods constitute an object. The first attribute in any object is the logical_name. It is one part of the identification of the object. Objects that share common characteristics are generalized as an interface class with a class_id. Instantiations of an interface class are called COSEM objects. IEC 62056-62 defines 19 interface classes for COSEM object model.IEC 62056-21
IEC 61107 or currently IEC 62056-21, was an international standard for a computer protocolCommunications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
to read utility meters. It is designed to operate over any media, including the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
. A meter sends ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
(in modes A..D) or HDLC (mode E) data to a nearby hand-held unit (HHU) using a serial port
Serial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
. The physical media are usually either modulated light, sent with an LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
and received with a photodiode
Photodiode
A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation.The common, traditional solar cell used to generateelectric solar power is a large area photodiode....
, or a pair of wires, usually modulated by a 20mA current loop
Current loop
A current loop describes two different electrical signalling schemes.- Digital :For digital serial communications, a current loop is a communication interface that uses current instead of voltage for signaling...
. The protocol is usually half-duplex
Duplex (telecommunications)
A duplex communication system is a system composed of two connected parties or devices that can communicate with one another in both directions. The term multiplexing is used when describing communication between more than two parties or devices....
.
The following exchange usually takes a second or two, and occurs when a person from the utility company presses a meter-reading gun against a transparent faceplate on the meter, or plugs into the metering bus at the mailbox of an apartment building.
The general protocol consists of a "sign on" sequence, in which a handheld unit identifies itself to the metering unit. During sign-on, the handheld unit addresses a particular meter by number. The meter and hand-held unit negotiate various parameters such as the maximum frame length during transmission and reception,Whether multiple frames can be sent without acknowledging individual frames(Windowing), the fastest communication rate that they can both manage(only in case of mode E switching to HDLC) etc.
Next the meter informs the hand held unit about the various parameters that are available with it in various security settings viz. the 'no security logical group', ' the low security logical groups' and ' the high security logical groups'.
If the parameter required is in no security group, just a get.request will provide the HHU with the desired response. If the parameter required is in low security group, a password authentication of the HHU is required before information can be read.
In case of high security parameters,the meter challenges the hand held unit with a cryptographic password. The hand held unit must return an encrypted password. If the password exchange is ok, the meter accepts the hand held unit- it is "signed on."
After signing on, the hand held unit generally reads a meter description. This describes some registers that describe the current count of metered units (i.e. kilowatt hours, megajoules, litres of gas or water) and the metering unit's reliability (is it still operating ok?). Occasionally a manufacturer will invent a new quantity to measure, and in this case, a new or different data type will appear in the meter definition. Most metering units have special modes for calibration and resetting meter registers. These modes are usually protected by anti-tampering features such as switches that sense if the meter enclosure has been opened.
The HHU may also be given limited rights to set or reset certain parameters in the meter.
The hand held unit then sends a sign-off message, and the meter automatically signs off after a previously negotiated time interval after the last message, if no sign-off message is sent.
See also
- IEC 61107
- ANSI C12.18
- Electricity meterElectricity meterAn electricity meter or energy meter is a device that measures the amount of electric energy consumed by a residence, business, or an electrically powered device....
- Automatic meter readingAutomatic meter readingAutomatic meter reading, or AMR, is the technology of automatically collecting consumption, diagnostic, and status data from water meter or energy metering devices and transferring that data to a central database for billing, troubleshooting, and analyzing.This technology mainly saves utility...
- Universal Metering InterfaceUniversal Metering InterfaceUMI is a set of 3 free open specifications for smart metering and smart home products. The UMI specifications define; a module interface based on SPI, an optical communications interface based on EN62056-21 and a security interface based on ECC-256 and AES-128...
(UMI)