An optical transceiver unit for an optical WDM transmitting and receiving device is taught, with a transmitting unit to which a data signal can be fed to a specified channel input port of a multiplexer unit, wherein a separate channel wavelength is allocated to each channel input port, and the transmitting unit can be tuned with respect to optical carrier wavelength across a specified range of wavelengths. The transmitting unit is constructed so that, within the specified range of wavelengths, discrete wavelengths can be set that correspond to the channel wavelengths. In tuning mode, the controller unit can drive the transmitting unit so that the possible channel wavelengths are scanned through. The controller unit evaluates the reception signal fed to it from the receiving unit for whether abort criteria for tuning mode have been fulfilled or not, wherein the scanning process is continued until the abort criteria are fulfilled.