This from the HomeVision mailing list…
If you disable the automatic DST option (using the User Location screen under the Configure menu), HomeVision won’t change the clock. You can change it manually on the appropriate days, or place commands in your schedule to set the clock ahead or back. However, HomeVision won’t know when you are in DST, and will therefore calculate sunrise and sunset times incorrectly (these times are an hour later during DST).
If you live in a country where DST ends the same time as the U.S., there’s a work-around that will work most times of the year. When DST is active in both countries (as it is now), you can enable HomeVision’s automatic DST adjustment, then download the schedule into HomeVision. If you previously had this option disabled, HomeVision will immediately move the clock ahead one hour. Reset the clock to the correct time using the Controller Time/Date screen under the Configure menu. HomeVision will now properly calculate sunrise and sunset times, and will also set the clock back an hour on the last Sunday in October. Thus, everything will work correctly until next spring (when HomeVision will be a week late in setting the clock ahead).
Custom Solutions, Inc. (a.k.a., HomeVision)”