Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1997-05-30
2001-07-03
Pascal, Leslie (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C359S199200, C359S199200
Reexamination Certificate
active
06256128
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to electricity metering and more particularly, to an electricity meter configurable to detect whether data is being supplied to the meter via a meter optical port or via an option board connector.
BACKGROUND OF THE INVENTION
In many electronic electricity meters, communications with the meter microcomputer can be performed via an optical port or an option board connector. For example, in some known meters, an electrical connector is provided so that various option boards, such as a telephone modem communication board, may be electrically connected to the meter microcomputer. In addition, an optical port electrically coupled to the meter microcomputer and accessible to devices external to the meter may also be provided. Asynchronous serial data may be communicated to the meter microcomputer via the optical port and the option board connector. All the meter data is available in a predefined format (an ANSI defined protocol) on the communication channel which connects the port and the option board connector to the microcomputer.
To prevent theft of or tampering with the metering data, it is desirable to control option board access to the meter microcomputer via the communication channel. Preventing such access, however, should not inhibit communication with the meter microcomputer via the optical port.
It would be desirable to provide a data source identification unit, or circuit, which transmits a signal to the meter microcomputer indicative of the source of communication, i.e., either the optical port or the option board connector. It also would be desirable to provide such a circuit without significantly increasing the costs associated with fabrication of a meter.
SUMMARY OF THE INVENTION
These and other objects may be attained by an electricity meter which, in one embodiment, includes a detection circuit, or unit, coupled to the meter microcomputer which supplies a detection signal to the microcomputer indicative of the data source. Using the signal supplied by the detection unit, the microcomputer can determine whether to allow access, via the communication channel, to metering data and other data stored in the meter.
More particularly, and in an exemplary embodiment, the detection unit has three different modes, or states, of operation. These states of operation are sometimes referred to herein as the steady state, the optical port data transmit state, and the option board connector transmit state. The steady state refers to the condition of the unit when no data is being transmitted to the meter microcomputer from either optical port or the option board. In the steady state, the detection signal supplied to the microcomputer is high. In the optical port data transmit state, the detection signal transitions, as least momentarily, from a high state to a low state. In the option board connector transmit state, the detection signal remains in the high state even though data is being communicated to the microcomputer. The microcomputer, by detecting the state of the detection signal as well as the presence of data on the communication channel, can determine the source of the data. The microcomputer can then respond and allow access as appropriate.
The above described detection unit provides a signal, sometimes referred to herein as a detection signal, to the meter microcomputer indicative of the source of communication, i.e., either the optical port or the option board connector. Using such information, the microcomputer can then determine whether to allow access to the meter data. Such unit also is believed to be low in costs, in terms of both components and assembly labor.
REFERENCES:
patent: 5204768 (1993-04-01), Tsakiris et al.
patent: 5668977 (1997-09-01), Swanstrom et al.
patent: 5734328 (1998-03-01), Shinbori
Crittenden Curtis W.
Jamison John J.
Lavoie Gregory P.
Lee, Jr. Robert E.
Armstrong Teasdale LLP
General Electric Company
Horton Esq. Carl B.
Pascal Leslie
Wasserbauer Damian
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