Modular measuring device with distributed data and algorithms
A sensor module includes a sensor element with a transducer for emitting an electric analog primary signal, which depends on a measured value; and a circuit assembly for conditioning the primary signal and for unidirectional data communication of a digital signal, which depends on the primary signal, to a superordinated unit. The circuit assembly has the following components: a signal input for receiving the primary signal, which depends on the measured value; a secondary side, inductively coupling, plug connector element for connection to a primary side, inductively coupling, plug connector element of the superordinated unit for receiving an energy signal and for transferring a measurement signal; an energy supply circuit, which rectifies the energy signal and provides at least one direct voltage for supplying the sensor module components; an analog signal conditioning circuit for conditioning the primary signal to a secondary signal; an analog-digital converter for converting the secondary signal to a digital measurement signal; a modulator for modulating the received energy signal for transferring the measurement signal to a superordinated unit by means of load modulation; and a microcontroller for controlling the components of the circuit assembly.
1. A method for determining a measured variable, with a measuring device, comprising the steps of:
connecting a sensor module to a primary side, inductively coupling, plug connector element and initializing the sensor module;
beginning measured value recording directly after initializing the sensor module, wherein said measured values are analog values;
converting said analog values into digital values;
sending said digital values via a network, the network including a fieldbus or an ethernet network, to a superordinated unit by means of a communication telegram, wherein the communication telegram contains said digital values and a unique identification number, wherein said sensor module can only send said digital values and is not able to receive information from said superordinated unit;
identifying said sensor module by the superordinated unit based on said unique identification number; and
calculating the actual measured variable in said superordinated unit from said digital values with the help of calculating algorithms, based on required measuring device adjustment and calibration values associated with said sensor module and stored for said sensor module in said superordinated unit or said network, wherein the calibration values are exclusively provided from outside the sensor module.
2. The method as claimed in claim 1 , wherein:
the communication telegram further contains a test sum and/or status information, for error detection.
3. The method as claimed in claim 1 , wherein:
said calibration values are stored in a sensor database in said superordinated unit or said network.
4. The method as claimed in claim 1 , wherein:
historical data of said measured variable are stored in said network.
5. The method as claimed in claim 4 , wherein:
said historical data are stored in a sensor database in said superordinated unit or said network.
6. The method as claimed in claim 1 , wherein:
said communication telegram is converted and output in a protocol of said network.
7. The method as claimed in claim 1 , wherein:
said digital values are converted into said communication telegram by means of load modulation.
8. The method as claimed in claim 1 , wherein:
said measuring device comprises a pH glass electrode in form of a single-rod measuring chain.
9. The method as claimed in claim 8 , wherein:
said calibration values comprise a zero point and slope of said single-rod measuring chain.
10. The method as claimed in claim 1 , wherein:
other measuring devices are connected to said network via inductively coupling, plug connector elements.
11. The method as claimed in claim 10 , wherein:
calibration values of all measuring devices operating in said network are stored in a sensor database in said superordinated unit or said network.
12. The method as claimed in claim 10 , wherein:
calibration values of measuring devices whose startup is imminent are stored in a sensor database in said superordinated unit or said network.