Data processing: measuring – calibrating – or testing – Calibration or correction system
Reexamination Certificate
1998-10-07
2001-06-05
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Calibration or correction system
C702S104000, C439S620040
Reexamination Certificate
active
06243654
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to transducers and, more particularly, to a transducer assembly including a smart connector for interfacing with digital signal processing systems such as data acquisition and control systems.
2. Discussion of the Related Art
Transducers are used in a wide variety of applications requiring physical quantities to be converted into analog electrical signals or analog electrical signals to be converted into some type of physical phenomenon. Transducers that normally provide an analog electrical signal as output are called sensors whereas transducers that normally accept an analog electrical signal as input are called actuators. In use, both types of transducer are commonly located remotely of the signal processing equipment receiving or generating the analog electrical signals associated with the transducers so that signals to and from the transducer must usually be carried by wires extending from the transducer to any one of a variety of standard connectors, such as BNC or multi-pin digital connectors. The connectors are configured to mate with the signal processing equipment and will typically transmit the signals directly to the equipment without modification. The signal processing equipment, on the other hand, typically includes interface electronics in the form of analog signal conditioners (e.g., filters, amplifiers, etc.), analog-to-digital (for a sensor) or digital-to-analog (for an actuator) converters, digital communications, and/or non-volatile memory for storing and retrieving information relating to transducer identification, configuration settings and calibration or correction factors to be applied to the signal. In traditional signal processing equipment, such as commercially available data acquisition and control systems, the interface electronics is disposed within a relatively large (e.g., tens of cubic inches) cabinet or housing to which the analog transducer signal wires are connected via a standard connector. The transducer identification, configuration settings and calibration or correction factors, if provided, have heretofore been manually entered into the control or data acquisition equipment. The process of manually entering the aforementioned transducer information into the signal processing equipment is a potential source of errors, particularly if a large number of transducers are used in a system.
Recently, it has been proposed to include the transducer identification, configuration settings and calibration or correction factors in a device known as a Smart Transducer Interface Module (STIM) as defined in the IEEE 1451.2 standard, the contents of which are incorporated herein in their entirety. The IEEE 1451.2 standard requires that the transducer data (known as a Transducer Electronic Data Sheet or TEDS) be inseparable from the transducer itself in all modes of normal operation to maintain the traceability of the transducer identification, configuration, and calibration information, even if the transducers themselves are exchanged at a later time. The foregoing requirement can be met by including the transducer and the interface electronics in the same housing and running a digital signal cable from the STIM to the signal processing system using a standard connector; however, for some classes of transducers (temperature sensors such as thermocouples for example), the interface electronics adds unacceptable size and mass to the transducer. In addition, the IEEE 1451.2 digital signal interface is defined as a ten-wire connection, and routing so large a cable to what may be relatively inaccessible locations may not be practical.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to overcome the abovementioned disadvantages by storing information about the transducer in a digital connector assembly and connecting the transducer to the connector assembly using a fixed analog cable.
Some of the advantages of the present invention are that the transducer assembly can be switched between multiple external digital signal processing systems without the need of having to manually enter information about the transducer each time the transducer assembly is connected to a new external digital signal processing system, that standard transducers and mounting techniques can be used, that cabling costs can be reduced by minimizing the number of wires needed to connect the transducer with the connector, and that equipment costs can be reduced by performing signal processing operations locally.
A first aspect of the present invention is generally characterized in a transducer assembly for connection with a digital signal processing system including an analog transducer, a digital connector assembly movable relative to the analog transducer to facilitate connection with the digital signal processing system, and a cable permanently affixed between the analog transducer and the digital connector assembly to convey an analog transducer signal therebetween. The digital connector assembly includes a connector housing, a digital connector mounted by the connector housing to mate in a detachable manner with the digital signal processing system, and transducer interface circuitry disposed within the connector housing in a non-removable manner and including a digital storage device programmed to store digital transducer data, such as transducer identification, configuration settings and calibration or correction factors, for retrieval by the digital signal processing system. The transducer interface circuitry can also include signal conditioning circuitry and a microcontroller. Incorporating the transducer data memory and interface circuitry in the connector housing allows conventional transducers to be used so that users do not have to modify existing mounting techniques. Furthermore, by using a fixed cable to connect the transducer to the connector assembly, the transducer assembly provides traceability of the transducer and its calibration data.
Another aspect of the present invention is generally characterized in a transducer assembly for connection with an external digital signal processing system including an analog transducer, a digital connector assembly movable relative to the analog transducer to facilitate connection with the digital signal processing system, and a cable permanently affixed between the analog transducer and the digital connector assembly to convey an analog signal therebetween. The digital connector assembly includes a connector housing, a digital connector mounted by the connector housing to mate in a detachable manner with the digital signal processing system, and transducer interface circuitry disposed within the connector housing in a non-removable manner and including a digital storage device programmed to hold digital calibration and correction data for the transducer, signal conditioning means for receiving an analog transducer signal and providing a conditioned analog transducer signal, and a microprocessor for retrieving the calibration and correction data from the digital storage device and generating digital corrections which are applied to the analog transducer signal via the signal conditioning means.
Still another aspect of the present invention is generally characterized in a transducer assembly for connection with an external digital signal processing system including an analog transducer, a digital connector assembly movable relative to the analog transducer to facilitate connection of the transducer assembly to the digital signal processing system, and a cable permanently affixed between the analog transducer and the digital connector assembly to convey one of a conditioned and an unconditioned analog signal therebetween. The digital connector assembly includes a connector housing, a digital connector mounted by the connector housing to mate in a detachable manner with the digital signal processing system, and transducer interface circuitry disposed within the connector housing in a non-removable manner an
Johnson Robert N.
Woods Stanley P.
Barbee Manuel L.
Hoff Marc S.
Telemonitor, Inc.
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