IEC 61107
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IEC 61107, formerly called IEC 1107, is an international standard document that describes a widely-used computer protocol used to read utility meters in the European Union. The IEC considers it to be superseded by IEC 62056, but it remains in wide use because it is simple and well-accepted. It sends ASCII data using a serial port. The physical media are 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 half-duplex. IEC 1107 is related to, and sometimes wrongly confused with, the FLAG protocol.
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 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?). 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.
[edit] See also
- Electricity meter
- IEC 62056 - a more modern european meter protocol; IEC 61107 is a subset
- ANSI C12.18 - a similar protocol used in the U.S.
