A danger alarm system includes a plurality of detectors, each of which having a microprocessor, a current drain controllable by the microprocessor for data exchange with a central station, an address register, and a nonvolatile memory for containing an individual binary serial number. In order to allow with few exceptions the use of relayless detectors, the configuration of the detectors is determined by providing each detector with a unique binary serial number at the manufacturer's end, identifying and storing in an initialization routine the serial numbers, setting all detectors through a collective command in a discrete addressing mode and response mode for allowing each detector after being addressed by its own binary serial number to respond with a current pulse and subsequently after being addressed with the binary serial number of another detector to check the occurrence or absence of a current pulse and to store the test result as binary pattern, polling the stored binary pattern from each detector and forming from this pattern and from the binary serial numbers of the respective detectors a first matrix and a second matrix which is defined by the column sums and line sums of the first matrix, and by evaluating the first and second matrices in accordance with a given algorithm for determining the system configuration.