Abstract:
Exemplary embodiments are directed to processing a sensor signal using the correction parameters assigned to the sensor. A pressure transducer is disclosed for measuring and converting absolute pressure and/or differential pressure into an adequate electrical measurement signal with the aid of a processing unit having an associated read-only memory, in which is stored a set of correction parameters for correcting the measurement signal.

Description:
RELATED APPLICATION  
       [0001]     The present application claims the benefit under 35 U.S.C. §119 of the fling date of German Application No. 20 2006 002263.5, filed Feb. 14, 2006, the contents of which are hereby incorporate by reference in their entirety.  
       FIELD  
       [0002]     A pressure transducer is disclosed for measuring and converting absolute pressure and/or differential pressure into an adequate electrical measurement signal.  
       BACKGROUND  
       [0003]     Information exists on such pressure transducers, such as in DE 35 12 529 A1, which for example, describes such devices in detail.  
         [0004]     The electrical signal S, which is generated in the conversion of the non-electrical quantity differential pressure dp=p 1 −p 2 , being the difference of a first process pressure p 1  and a second process pressure p 2 , into an electrical quantity, exhibits dependencies S 2 =f(p) on the absolute pressure p=(p 1 +p 2 )/2 and S 3 =f(θ) on the temperature θ inside the differential pressure transducer, which exist in addition to the dependency S 1 =f(dp) as a result of given material constants. The electrical signal S=f(dp,p,θ) is a function of the differential pressure dp, of the absolute pressure p and of the temperature θ. The dependency of the electrical signal S on the absolute pressure p and temperature θ can distort a converted measured value.  
         [0005]     EP 0 178 368 A2, which is based on a sensor arrangement having a differential pressure sensor, a temperature sensor and a sensor for the static pressure, discloses calculating a corrected differential pressure signal using a linear polynomial function linking the three original measurement signals that can be detected at the sensors for differential pressure, temperature and static pressure. For this purpose, the coefficients of the polynomial function, which are weighted functions of the temperature and static pressure, are stored in a read-only memory.  
         [0006]     Irrespective of the manner of the correction, this read-only memory is physically assigned to the means of correction, usually a microprocessor, and hence is physically separate or separable from the sensor arrangement.  
         [0007]     Depending on the manufacturing process, but in particular during repairs, there is a risk that the pairing of a sensor arrangement with the associated read-only memory containing the associated set of correction parameters is lost. As a result, measured values are processed incorrectly, but not corrected.  
         [0008]     DE 201 05 505 U1 discloses an electronic analysis circuit situated directly beside the measurement cell in the oil-filled pressure chamber. The electronic analysis circuit is subjected to the process pressure. The permitted measurement range of the pressure transducer is limited by the allowed pressure that can be applied to the components of the electronic analysis circuit.  
       SUMMARY  
       [0009]     Exemplary embodiments are directed to processing a sensor signal solely using the correction parameters assigned to the sensor. A pressure transducer is disclosed for measuring and converting absolute pressure and/or differential pressure and converting into an adequate electrical measurement signal with the aid of a processing unit having an associated read-only memory, in which is stored a set of correction parameters for correcting the measurement signal.  
         [0010]     The read-only memory can be inseparably connected to the sensor arrangement, and detachably connected to the processing unit.  
         [0011]     This can ensure that the correction parameters are inevitably kept with the sensor of the sensor arrangement, thereby eliminating any mistakes or incorrect assignments between sensor and correction parameters.  
         [0012]     The read-only memory can have a serial data interface. This can keep down the number of connection leads emanating from inside the sensor arrangement.  
         [0013]     An A/D converter can be provided and inseparably connected to the sensor arrangement, the A/D converter being connected to the serial data interface.  
         [0014]     The sensor arrangement can be inseparably connected to a microcontroller, which is connected to the serial data interface, and in which an address-decoding program is loaded for the read-only memory and the A/D converter.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     Exemplary embodiments will be described herein with reference to drawings in which:  
         [0016]      FIG. 1  shows a schematic cross-section of an exemplary sensor arrangement in a transducer; and  
         [0017]      FIG. 2  shows a block diagram of an exemplary measurement signal processing. 
     
    
     DETAILED DESCRIPTION  
       [0018]      FIG. 1  shows a cross-sectional view of a sensor arrangement. This essentially comprises a differential pressure sensor  10  having a first and a second pressure inlet, which is located in an oil-filled housing  20  comprising a housing base  21  and a housing cover  22 . A first pressure port  23  for admitting a first process pressure  31  is fitted in the housing base  21 , the differential pressure sensor  10  being mounted on this pressure port. The first process pressure  31  acts on the first pressure inlet of the differential pressure sensor  10  via a chemical seal.  
         [0019]     In addition, a second pressure port  24  for admitting a second process pressure  32  is fitted in the housing base  21 . The second process pressure  32  acts on the second pressure inlet of the differential pressure sensor  10  via the oil in the housing.  
         [0020]     An electronic circuit  40  is mounted on the differential pressure sensor  10 . It contains at least one read-only memory  41 , which can be permanently assigned to the differential pressure sensor  10  and inseparably connected (e.g., fixedly connected so as not to be configured for ready detachment) to the differential pressure sensor  10 . A set of correction parameters for correcting the measurement signal is stored in the read-only memory  41 . By this means, if the sensor arrangement is replaced during repair, the associated correction parameters are inevitably replaced as well. This avoids a measurement signal being distorted by applying correction parameters from a different differential pressure sensor  10 .  
         [0021]     The differential pressure sensor  10  is detachably connected to a processing unit  50  located outside the housing  20 . For this purpose, connection leads emanating from the differential pressure sensor  10  are taken out of the housing  20  via contact pins  33  fitted in the housing base  21  and insulated from it. The processing unit  50  is connected to these contact pins  33 . A serial protocol is provided for communication between the differential pressure sensor  10  and the processing unit  50 , so that it is possible to manage with a small number of contact pins  33  designed as electrical feedthroughs.  
         [0022]      FIG. 2  shows a block diagram of the measurement signal processing, where the same references are used for the same means. The differential pressure sensor  10  and the electronic circuit  40  are arranged in the housing  20  and connected via a serial data interface  60 . The processing unit  50  can be detachably connected to the serial data interface  60  outside the housing  20 .  
         [0023]     In a first exemplary embodiment, the electronic circuit  40  has a read-only memory  41 , in which is stored a set of correction parameters for correcting the measurement signal.  
         [0024]     In another embodiment, the electronic circuit  40  also comprises an A/D converter  42 , which is inseparably connected to the differential pressure sensor  10 . The A/D converter  42  is connected to the serial data interface  60 . The analog differential pressure signal is thereby digitized directly in the differential pressure sensor  10 , and transmitted in digitally encoded form via the serial data interface  60  to the processing unit  50  located outside the housing  20 . The transmission of digitally encoded signals can be less sensitive to noise than the transmission of analog signals. Such a feature can be particularly relevant to the use of pressure transducers of the type in question in the industrial environment.  
         [0025]     In a further embodiment, it is provided that the electronic circuit  40  comprises a microcontroller  43 , which is connected to the serial data interface  60 . An address-decoding program for the read-only memory  41  and the A/D converter  42  is loaded in the microcontroller  43 . Despite a large number of devices in the electronic circuit  40 , it can thereby be possible to manage with a small number of contact pins  33  designed as electrical feedthroughs.  
         [0026]     It is also possible using these means to operate different bus systems over the same communications channel. The protocol of the bus system currently in use can be detected and applied by the microcontroller  43 .  
         [0027]     It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.  
       LIST OF REFERENCES  
       [0000]    
       
           10  differential pressure sensor  
           20  housing  
           21  housing base  
           22  housing cover  
           23  first pressure port  
           24  second pressure port  
           31  first process pressure  
           32  second process pressure  
           33  contact pin  
           40  electronic circuit  
           41  read-only memory  
           42  A/D converter  
           43  microcontroller  
           50  processing unit  
           60  serial data interface