EP0178368A2
Expired / Lapsed
EP
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Process variable transmitter and method for correcting its output signal
Assignee: Honeywell Inc
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Filing: 1985-01-30
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Granted: —
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Expires: 2005-01-30
Abstract
Abstract For calibrating a process variable transmitter the process variable (PV) is sensed and the analog output signal of the sensor (4.6) is converted to a digital signal. The digital signal is corrected by a microprocessor (12) using a characterization equation previously individually developed during a manufacturing testing of the process variable transmitter over a predetermined range of environmental stimuli to ascertain the coefficients for a polynomial in the form of PV = A 0 + A 1 P + A 2 P 2 + ...A i P i . This characterization equation is stored in a non-volatile memory (14). The digital computer produces a digital process variable representation modified in accordance with said equation. Subsequently, the digital output from the computer is converted to a conventional 4-20 mA analog signal for use as a process control signal.
Inventors
- 👤 John R. Malloy
- 👤 Arthur M. Olsen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 19:10
CPC Classifications
G; G08; G08C; G08C19/00; G08C19/02; G01; G01D; G01D18/00; G01D18/008; G01L; G01L27/00; G01L27/002
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
75 words
A method for calibration of a process variable transmitter characterized b y the steps of a) measuring a process variable by means of a process variable sensor; b) converting the measured process variable into a digital representation thereof; and c) supplying the digital representation to a digital computer to be used in computing a digital output in accordance with a stored characterization equation which is a function of the operation of the process variable sensor.
Claim 2
Independent Claim
75 words
A method for calibration of a process variable transmitter characterized b y the steps of a) measuring a process variable by means of a process variable sensor; b) converting the measured process variable into a digital representation thereof; and c) supplying the digital representation to a digital computer to be used in computing a digital output in accordance with a stored characterization equation which is a function of the operation of the process variable sensor.
Claim 3
Dependent Claim
26 words
A method according to Claim 1, characterized b y the further step of converting the digital output from the digital computer into an analog control signal.
Claim 4
Dependent Claim
41 words
A method according to Claim 1., characterized in that the characterization equation is in the 2 i form of a polynom PV = A o + A 1 P + A 2 P 2 + ...+ A i P i .
Claim 5
Dependent Claim
12 words
A method according to Claim 3, characterized in that i ⋦ 5.
Claim 6
Dependent Claim
81 words
A process variable transmitter comprising a process variable sensor (4,6) and an analog-to-digital converter (10) for converting an analog output signal of said sensor into a digital equivalent thereof, characterized b y a non-volatile memory (14) for storing a transmitter characterization equation, and a digital computer (12) connected to said converter (10) and to said memory (14) for computing a digital output signal representative of the digital equivalent of the sensor output signal modified in accordance with the stored characterization equation.
Claim 7
Dependent Claim
81 words
A process variable transmitter comprising a process variable sensor (4,6) and an analog-to-digital converter (10) for converting an analog output signal of said sensor into a digital equivalent thereof, characterized b y a non-volatile memory (14) for storing a transmitter characterization equation, and a digital computer (12) connected to said converter (10) and to said memory (14) for computing a digital output signal representative of the digital equivalent of the sensor output signal modified in accordance with the stored characterization equation.
Claim 8
Dependent Claim
37 words
A pressure transmitter according to Claim 5, characterized by a digital-to-analog converter (16) for converting the digital output signal of said computer (12) into an analog output signal, preferably a 4 to 20 mA standard control signal.
Claim 9
Dependent Claim
32 words
A pressure transmitter according to Claim 6, characterized in t h a t a DC supply voltage is fed to the transmitter via the same line (20) carrying the analog output signal.
Claim 10
Dependent Claim
48 words
A pressure transmitter according to Claim 5, characterized in t h a t said characterization equation is in the form of a polynom PV = A 0 + A 1 p + A 2 P 2 + ... + A i P i and wherein i ⋦ 5.
References Cited (Backward Citations)
No citation records indexed.
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