Abstract: The invention relates to an assembly for providing a long-term ECG. The assembly comprises a portable ECG device (1), which is designed and intended to record, for a defined or definable time period, an ECG of a patient who can be associated with the ECG device (1), and an application software (2) for the ECG device (1) that can be executed on a mobile device (3) or on a computer. By means of the application software (2), parameters of the ECG device (1) can be set and data recorded by the ECG device (1) can be read out and displayed. Furthermore, the application software (2) is designed to visually instruct an operating person in the electrode placement for an ECG and to detect and evaluate parameters of the ECG device (1) and/or of an ECG cable (41-43) connected to the ECG device (1).