Help with probe offset

I figure this is the wrong place for this but I do not know where..

I set up my auto level with the normal procedure but I would like to move the bed slightly up or down with changes in filament. I have two things I can modify: probe offset and home offset in the eeprom. What is the correct way to trim the offset. Without the auto level I generally track my printing by adjusting the home offset by +/- .01 every print which seems to correct for what drift is associated with the machines.

I set up the offsets in the usual way: z offset followed by fine tune offset, and got Home:-11.3 and Probe -16.27. It looks like it stores the absolute distance to the bed instead of the offset from Home like in Marlin. If I adjust the bed it seems to move in the right direction, but it is not logical as the Probe offset has not been changed.

I sure wish Robo had written a manual that explained what these variables did.

What does adjusting probe offset in the eeprom do? Does it have any effect after the initial set up? What happens if I reboot my R2?

Here is what I do: I decrease or increase both the Probe offset and the home offset by the identical amount to move the bed up or down for the next print. If I turn off the R2 then back on it returns to the same position. I assume they stored the absolute value of Probe offset rather than the distance between the nozzle and the sensor. On turn on the must send the M851 command the difference between the two, as the offset distance. I can just set the home offset and the bed position moves, but on turn off/on the real offset distance is sent incorrectly.

 

I have a few glass plates. I pull one off at the end of print and put another on. The probe works well for that. The values stored in the eeprom are static, they do not change. When I powered off my machine it was all screwed up when I turned it back on having just modified the Home offset.

I am going to experiment with modifying both values for trim. Now I suspect the R2 sends Marlin the difference between the two with m851 on turn on or reset, so if I do not modify both the reset screws me.

On another note: I have been playing with auto tuning. I found that I get much better results if I auto tune the bed at 50C and the extruder at 150C. The values calculated at these lower temps work much better at high temp than the values calculated at high temps. I have modified the Marlin code to intercept the M303 command and substitute 150C for the 240C and 50C for the 80C. This also protects my Flexplate system from over temp. I found the beds that would not auto tune at 80C have no problem at 50C. If anyone wants to play; the command from terminal mode is M303 E-1 C10 S50 for the bed @50C and M303 E0 C10 S150 for the extruder at 150C. Read the values and then enter them with the EEprom editor (UPLOAD), CAPS matter.