Honeywell Thor VM2 User Manual page 40

Off Mode
By default, pressing the power button shuts down the Thor VM2. This behavior can be
modified. See
The Thor VM2 is also off when it is not connected to a power source and the UPS battery
is depleted. However, an internal Real Time Clock (RTC) powered by an internal battery
maintains the date and time while the Thor VM2 is off.
40 Thor VM2 with with Microsoft Windows 7 or Windows Embedded Standard User Guide
Choose What the Power Button Does.