While I have never used a math function on the logo timer, Siemens web site says it can do it.
However, as the program I have in the logo totals daily stoker run time, you could manually multiply coal pounds per hour to get stoker coal pounds per day usage. By subtracting stoker daily run time from total time in the day, you could get your idle time per day to calculate idling coal usage.
I check the daily stoker run time sometimes out of curiosity when I am getting something from the cellar. I recently changed from fall to winter mode by changing from 4 to 5 teeth, changed the out fire time from 30 minutes to 40, and cleaned the firebox. It dropped the dailey run time by an hour.
My daughter changes the ashes, so unless I get a telephone call from the boiler notifying me that she forgot, I am the same as Rob, I don't normally check the boiler data (or the boiler for that matter).