Modular system, in particular modularly constructed energy store, wherein the modular system has a central unit (4, 5) and modules (M0,..., MN), wherein the modules (M0,..., MN) are spatially separated or directly connected to one another, wherein each module has a circuit arrangement with a temperature sensor (R_T), wherein each circuit arrangement generates an output voltage signal, in particular as analogue voltage, characterised in that: the circuit arrangements are arranged in series, wherein the output voltage signal of one circuit arrangement is supplied as input signal to a circuit arrangement arranged directly downstream in the series, wherein the output voltage signal of the last circuit arrangement in the series is supplied to a central unit (4, 5), the system is configured in such a way that a voltage signal representing the highest temperature value determined in the modules (M0,..., MN) and/or a voltage signal representing a cable break state is passed to a central unit (4, 5) via a single signal line, in particular evaluation unit with interface and consumers, in the series arrangement of the circuit arrangements the voltage signal representing the temperature value determined by the temperature sensor (R_T) is supplied to a respective circuit arrangement of the circuit arrangement arranged directly downstream in the series as input signal and wherein the voltage signal representing the temperature value determined by the temperature sensor (R_T) is supplied to the last circuit arrangement of the central unit (4, 5) in the series, in the respective circuit arrangement the voltage signal representing the temperature value determined by the temperature sensor (R_T) is passed on to the circuit arrangement as output voltage as long as the input voltage is not greater, and otherwise the input voltage is passed on as output voltage, the input signal of the circuit arrangement of the first module is set to a fixed potential. the circuit arrangements are arranged in series, wherein the output voltage signal of one circuit arrangement is supplied as input signal to a circuit arrangement arranged directly downstream in the series, wherein the output voltage signal of the last circuit arrangement in the series is supplied to a central unit (4, 5), the system is configured in such a way that a voltage signal representing the highest temperature value determined in the modules (M0,..., MN) and/or a voltage signal representing a cable break state is passed to a central unit (4, 5) via a single signal line, in particular evaluation unit with interface and consumers, in the series arrangement of the circuit arrangements the voltage signal representing the temperature value determined by the temperature sensor (R_T) is supplied to a respective circuit arrangement of the circuit arrangement arranged directly downstream in the series as input signal and wherein the voltage signal representing the temperature value determined by the temperature sensor (R_T) is supplied to the last circuit arrangement of the central unit (4, 5) in the series, in the respective circuit arrangement the voltage signal representing the temperature value determined by the temperature sensor (R_T) is passed on to the circuit arrangement as output voltage as long as the input voltage is not greater, and otherwise the input voltage is passed on as output voltage, the input signal of the circuit arrangement of the first module is set to a fixed potential.