Magnetic-inductive flowmeter

A magnetic-inductive flowmeter for ascertaining a flow-velocity-dependent measurement variable of a flowable medium, comprising:

• a measuring tube for conducting the medium;
• at least one measurement electrode arranged on the measuring tube;
• an additional electrode arranged on the measuring tube;
• a magnetic-field-generating device for generating a magnetic field that penetrates the measuring tube at least in portions;
• a measuring circuit with a microcontroller,
• wherein the measuring circuit has a first analog-to-digital converter, which is electrically connected to the at least one measurement electrode and the microcontroller,
• wherein the first analog-to-digital converter is configured to convert an analog flow measurement signal provided via the at least one measurement electrode into a digital flow measurement signal,
• wherein the measuring circuit has a digital-to-analog converter, which is electrically connected to the additional electrode,
• wherein the digital-to-analog converter is configured to convert a digital supplied test signal provided via the microcontroller into an analog supplied test signal and to feed the latter into the additional electrode,
• wherein the measuring circuit has a second analog-to-digital converter, which is electrically connected to the additional electrode,
• wherein the second analog-to-digital converter is configured to convert an analog test measurement signal provided via the additional electrode into a digital test measurement signal,
• wherein the microcontroller is configured to extract the component of the digital test measurement signal from the digital flow measurement signal using a correlation and to determine the flow-velocity-dependent measurement variable using the corrected flow measurement signal, and/or
• wherein the microcontroller is configured to determine a diagnostic variable or a process variable on the basis of the digital test measurement signal.