A method for calculating coordinate values of a measuring machine is provided. The method includes receiving signals in three dimensions from a raster ruler signal generator, identifying a direction of each signal and multiply a frequency of each signal. The method further includes counting each of multiplied signals in each dimension, sending the counted data to the MCU. The method further includes adding the counted data of each of the multiplied signals in each dimension to obtain an accumulated number in each dimension and calculating coordinate values of the measuring machine according to the accumulated number in each dimension and a proportionality factor of the raster ruler signal generator.