A wind turbine rotor blade has a blade root, a blade tip and a blade depth varying over the length of the rotor blade. Upon completion of the decoding of the variable-length code stream of the block of interest, a data length of a semi-fixed-length data stream of the block of interest is calculated. By means of the present invention, an external device can be commissioned on a host end, thereby improving the working efficiency of commissioning the external device. This information is entered into the mathematical model in order to update the registration between the image set and a display showing the position of the locatable guide. After the analysis, the one or more processor cores are recomposed into the logical processor to handle the change in the operating status.