초록 ▼

A two-wire, admittance-responsive instrument system in which a transmitter, receiver and calibrator are connected by a two-wire transmission line is disclosed. The calibrator repetitively transmits a calibration enabling signal causing the transmitter to increment a reference admittance for comparis

A two-wire, admittance-responsive instrument system in which a transmitter, receiver and calibrator are connected by a two-wire transmission line is disclosed. The calibrator repetitively transmits a calibration enabling signal causing the transmitter to increment a reference admittance for comparison to a sensed admittance corresponding to a known physical condition. The calibrator monitors the bistable output signals transmitted by the transmitter in the calibration mode, which changes state when the incremented reference admittance bears a predetermined relationship to the sensed admittance. The calibrator may then transmit additional calibration enabling signals causing preload to be established for transmitter operation.

대표청구항 ▼

A two-wire transmitter system comprising: a power supply at one location; a two-wire transmitter at another remote location connected to said power supply by a pair of transmission lines, the transmitter comprising: an admittance sensing probe for generating an input signal having a value representa

A two-wire transmitter system comprising: a power supply at one location; a two-wire transmitter at another remote location connected to said power supply by a pair of transmission lines, the transmitter comprising: an admittance sensing probe for generating an input signal having a value representative of a sensed condition and corresponding admittance of materials; an admittance responsive network coupled to said probe for comparing said input signal to a reference signal; output means coupled to said admittacne responsive network for providing an output signal over said transmission lines whenever a predetermined relationship exists between the values of the input signal and reference signal; and admittance calibrating means coupled to said admittance responsive network for generating calibrating signals in response to receipt of enabling signals supplied by a remotely located calibration enabling means coupled to the transmission lines, the enbling signals being supplied to the transmitter over the transmission lines, the value of the reference signal being varied in response to generation of the calibrating signals to provide a new reference signal.