I have populated the axis area with numbers matching what i am seeing in the datalogger 0 -5 -10 -15 -20 -25 inhg, i have put 0 5 10 15 20 25 inhg as well. i have used Kpa instead both negative and positive and all i manage to do is change whether it uses the top or bottom line of of the slope table. If you have some idea on what scale to use i am all ears.