LVM files can only be written from the dynamic data type, which internally is an array of waveforms. Hence, any kind of numeric data that can be converted into a double precision float can be wired. Strings (or e.g. time stamps) cannot be used immediately - they need to be converted. Wire the string array to a "fract/exp string to number" function which will take care of the whole array, given that all entries can be converted to numbers. Configure the Express VI to not write time columns.
