In a method for a data transmission between first and second modules, and a system having mobile parts for performing the method: the time bases of the first and second modules are synchronized; transmitters of the first module emit a light signal pulse individually one after the other and/or in numbered order in a respective time range; the particular receiver of the second module at which the strongest receive signal occurs is determined, the particular time range and/or the number of the particular time range being determined in which the strongest receive signal occurs; the determined time range and/or the determined number is/are transmitted from the second module to the first module; and the transmitter of the first module associated with the determined time range and/or to the determined number is determined and used for the subsequent data transmission from the first module to the second module.