Abstract: A method and an apparatus for measuring electrical properties of communication lines is presented, wherein the communication line comprises a first line and a second line, wherein the first line is connected to a first line driver and the second line is connected to a second line driver. At least one measurement for determining said properties of said communication line is performed with the first line driver or the second line driver set to a high impedance state. With this method and apparatus, detailed line testing can be performed without the need for additional elements in a communication circuit.

Abstract: A method measures at least one capacitive property of a communication line. The communication line includes a first line and a second line. The method includes applying at least a first voltage ramp to at least one of the first line and the second line, measuring at least a first current flowing via the at least one of the first line and the second line during the first voltage ramp, and calculating the capacitive property based on the first measured current.

Abstract: Method for supplying a circuit unit (201) which is to be supplied with different supply voltages, in which the circuit unit (201) to be supplied is protected against overvoltages, having the following steps: application of at least two supply voltages (203a, 203b) with respect to a ground potential (210) to the circuit unit (201) to be supplied; connection of signal connections (208, 209) of the circuit unit (201) to signal lines (206, 207) for transmission of signals between the circuit unit (201) and external circuit units; emission of a reference voltage (204) from a control connection (212) of the circuit unit (201) to an overvoltage protective device (205), in that a supply voltage (203a, 203b) is passed on to the control connection (212) by means of a switching module (211); and tripping of the overvoltage protective device (205) on detection of an overvoltage which occurs with respect to the reference voltage (204) on at least one of the two signal lines (206, 207).

Abstract: A method and an apparatus for measuring electrical properties of communication lines is presented, wherein the communication line comprises a first line and a second line, wherein the first line is connected to a first line driver and the second line is connected to a second line driver. At least one measurement for determining said properties of said communication line is performed with the first line driver or the second line driver set to a high impedance state. With this method and apparatus, detailed line testing can be performed without the need for additional elements in a communication circuit.