I got my ResMed S9 Autoset at the end of August and have been using it for a week. Super quiet and ease-to-use machine. It's a far cry from my previous PR Series M base model machine. I am very happy about it.
I just downloaded SleepHead and imported the data. The reports showed that the time was off by 3 hours (early). Obviously, my DME did not set it correctly to the Eastern time zone. So I went into the clinician set-up menu (thanks to the board here for making public the "secret" of DMEs). I did this after midnight yesterday. It allowed me to change the time forward but the date was changed by one day. When I changed the date back to the correct day, it gave me the error message: "Invalid date/time, data exists for this period". I did not use the S9 on Tuesday, hoping that I would be able to set the correct date by not feeding the machine with Sep 4/Sep5 data.
This morning, I check the machine date and time. It was "6/Sep/2012, 10:40" when the correct date and time should be 5/Sep/2012 10:40. I tried to change the date back to Sep 5, but it gave the invalid date/time message although I did not use the machine on Tuesday night (Sep 4/Sep 5). Right now I have to keep the date as Sep 6.
I read a no. of posts from here and another board. Some said that you have to erase the data in order to change date/time. I could find answers relevant to my situation. I appreciate any help.