The "Auto-Save" settings allow you to automatically save data or graphical images at an interval of your choice.

Auto-save data 

Turning this setting on will cause PingPlotter to save a .pp2 file at the interval you choose.  You should specify the directory you’d like to save in, and you should also include some variable as part of the name – otherwise every save will overwrite the previous save.

Auto-save image 

Automatically saving an image is an interesting way to create a history, or to update a web page with data automatically.  Note that the written image will always look like whatever’s on the PingPlotter screen – so if you’re looking at some period besides the current period, *that* image will be saved (possibly multiple times).

Changing the "File Type" here also controls the default file type when saving from the main screen – so even if you’re not auto-saving, you can change this value to set that default.
Variables:  Both the data and the image filenames use variable substitution.

Maximum samples held in memory.

Long-term monitoring sessions might start to fill up memory, making things run slower.  If you want to purge off old samples when memory starts to get full, set this.  Make sure you’re auto-saving the old data, though, or it will be lost forever!