Hi Dan, Sergio just asked me to send you the format of the PMS files. Usually we only save few columns in the CSV files. But the Matlab programs I gave you are configured to read a specific format, which is as follow: 1)Sample Date 2)Sample Time 3)Sample Value 4)Units 5)Flow Rate 6)Laser Status 7)Micron Size 0 8)Counts/Channel 0 9)Micron Size 1 10)Counts/Channel 1 11)Micron Size 2 12)Counts/Channel 2 13)Micron Size 3 14)Counts/Channel 3 15)Micron Size 4 16)Counts/Channel 4 17)Micron Size 5 18)Counts/Channel 5 If you keep this configuration, you will not have to modify the Matlab programs. ;-)