Jump to content

IEC 62056

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Woohookitty (talk | contribs) at 07:21, 4 July 2005 (→Links: Stubsensor cleanup project; please see the article_discrepancy section if you wish to revert.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

IEC 62056, also called DLM/COSEM is an international standard document that describes a computer protocol used to read utility meters in the European Union. It is designed to operate over any media, including the internet. A meter usually sends ASCII data to a nearby hand-held unit 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 EIA-485. 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 the fastest communication rate that they can both manage. Next, 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 hand held unit then sends a sign-off message, and the meter automatically signs off a minute after the last message, if no sign-off message is sent.

Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=IEC_62056&oldid=18116885"