Meriam M2 – Series Smart Manometer - Manual (Page 11)

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the display. The  key is used to scroll through
programmable registers with the unit in the Program
Mode. Once a programmable register is selected the 
key can be used to edit that register.
Prgm &  (enter) KEY
Puts the manometer into the Program Mode from the
Measure Mode. When in the Program Mode, pressing
this key selects the programmable register to be edited
(with prompt for password if Lockout is set). After the
register has been edited, pressing the PRGM key enters
the new setting into the manometer’s non-volatile memory.
This key also acts as a  key when editing user input
such as the header name and user units.
Backlight Key
The BACKLIGHT key, represented by the standard light
bulb symbol, toggles the display backlight between green
and off.
The backlight consumes additional
battery energy. Turn the backlight off
to optimize battery life.
2. Zeroing the Manometer
To Zero DN, DI, GI or CI Type Manometers
Disconnect from pressure sources and vent the pressure
port(s) to atmosphere (do not remove the factory installed
P2 plug if present). The display should read close to zero.
Press the Min/Max and Hold keys at the same time (see
inset photo below) and then release. The top line of the
display reads “ZERO IN PROGRESS” and the bottom line
counts down from 9. The process is complete when the
unit returns to Measure Mode. The lockout function, if
enabled, does not prevent zeroing of the manometer.
NOTE: The smart manometer can
only be zeroed if the new zero value
is within +/-5% (of FS) of the original
factory calibrated zero. If the zero
procedure generates a new zero
value outside this limit a “ZERO
RANGE ERROR” message appears
indicating that the procedure failed.
Factory service may be required.