V100 (2019-11)
Doc. Ref. XGC-320-100119
27
settings. If your XGC-320 has been previously configured and
relay setpoints and linear analog output pressure settings have
been programmed, changing units-of-measure will return the re-
lays setpoints and the linear analog output pressure settings to
factory default setting values in Torr. In this case, you must re-
program the relay setpoints and linear analog output pressure
settings in the newly programmed units-of-measure.
SET ATM
1. To set the atmospheric pressure reading (also known as the
"span" adjustment), flow nitrogen gas or air into your closed
vacuum chamber to allow the pressure to rise to a known
value above 400 Torr. Alternatively, if your local uncorrected
barometric pressure (air) is known, simply vent your vacuum
system chamber to expose the gauge to the local atmospheric
pressure.
2. Go to the SET ATM screen. When the desired pressure is
stable, adjust the displayed pressure reading on the XGC-320
to the known value using the INCR (increase) or DECR (de-
crease) keys. Press the SAVE/EXIT key to save the new at-
mospheric (span) pressure value. For example, if your known
local uncorrected barometric pressure is 760 Torr, enter 760
in the SET ATM screen. The main pressure measurement
screen will now display 760 Torr while the gauge is at atmos-
phere.
It is good practice to perform the sequence of checking and
adjusting span (ATM) then zero (VAC) and then, finally recheck-
ing the span setting to ensure that the circuitry is properly bal-
anced for use in measuring pressure throughout the intended
measurement range.
SP1 ON and SP2 ON
[Factory default = 100 mTORR]
These setpoints correspond to the pressures at which the relays
will turn on (energize). The relays will turn on when the pressure
is below the programmed pressure value. If you are unable to
increase the values of SP1 ON or SP2 ON, you must first go to
SP1 OFF or SP2 OFF and increase those values to a number
higher than the values of SP1 ON or SP2 ON you are trying to
set.