Abstract: A description is given of a measuring instrument to be connected to a higher-order unit having at least a first and an identical second pair of terminals, which can be connected electrically, very simply and without errors, to the higher-order unit, the measuring instrument comprising: a first pair of lines, to be connected to the first pair of terminals, via which a signal current flows during operation, the signal current being a measure of an instantaneous measured value, and a second pair of lines, to be connected to the second pair of terminals, via which a supply current flows during operation, whose value is greater than or equal to a minimum signal current and less than or equal to a maximum signal current.

Abstract: A description is given of a measuring instrument to be connected to a higher-order unit (57, 75) having at least a first and an identical second pair of terminals, which can be connected electrically, very simply and without errors, to the higher-order unit, the measuring instrument (61) comprising: a first pair of lines (1), to be connected to the first pair of terminals, via which a signal current flows during operation, the signal current being a measure of an instantaneous measured value, and a second pair of lines (3), to be connected to the second pair of terminals, via which a supply current flows during operation, whose value is greater than or equal to a minimum signal current and less than or equal to a maximum signal current.