A hardware module which operatively carries out a method of compressing mass spectral data, the method comprising: receiving a first signal output from an ion detector of a mass spectrometer; processing the first signal to a digital signal at an output being data frame types representative of the first signal output; temporarily storing the data frame types in a memory block and reading a data frame from the memory block and determining its data frame type and according to its data frame type compressing the data frame according to one or more compression algorithms to generate a compressed data output stream.