Vaisala WMT52 - Manual (Page 51)

Chapter 5 _______________________________________________ Wiring and Power Management
VAISALA_______________________________________________________________________ 49
NOTE While in Service mode and/or while supplied through the Service port
the WMT52 consumes 0.3 ... 0.6 mA more than in normal mode, when
supplied through the Main port (M12 connector or screw terminals).
When supplied through the Service port the minimum voltage level for
reliable operation is 6V. This can also be seen in the supply voltage
reading of the Supervisor message - the Vs value is 1V lower than the
actual input voltage.