Method and device for detecting faults in a perforated, moving web of material

In a method and a device for detecting faults in a perforated, moving web of material (1) the change in physical or geometric conditions of the surroundings is received from the direction of the web of material (1) on one side of the web of material by means of at last one sensor and is converted into an electric signal and the signal is evaluated in an evaluation device. In order to detect faulty perforations, a counter (6 to 9) advantageously receives clock pulses from a clock generator (11) in the time between two successive signals and adds the said clock pulses until it is reset by the subsequent signal, the said counter then signalling a fault if the number of added clock pulses exceeds a limit value or the counter overruns. The adaptation of the device to perforations of different sizes is effected by adjusting the clock frequency of the clock generator (11).