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I. Set Point Operation
When the displayed system pressure is less than the value of the set points, the set point relay is
turned on; the corresponding LED lights to indicate that the relay is energized. The relay will be
turned off when the pressure rises to 5% above the set point, plus 1 mTorr. For example:
If the set point is 30 mTorr, the set point relay will turn on at 30 mTorr; it will turn off at
[30 + 0.05*30 + 1]=32.5 mTorr, and higher pressures.
If the set point is 3 mTorr, the set point relay will turn on at 3 mTorr; it will turn off at
[3 + 0.05*30 + 1]=4.0 mTorr, and higher pressures.
If the set point is 1 torr, the set point relay will turn on at 1.00 torr; it will turn off at
[1.00 + 0.05*1.00 + 0.001]=1.05 torr, and higher pressures.
NOTE:
See also Section VIII - Application Note - Protective Circuits for Set Point Relays
J. Reading the Set Points
To see the value of a set point, push the
SELECT
button until the desired
SET
PT
LED
is flashing.
K. Setting the Set Points
The range for the set point settings is from 3 mTorr (mbar) to
500 torr (mbar). The
OFF
setting
disables the set point control and keeps the relays
from operating. The
OFF
setting is the lowest
setting, below 3 mTorr (µbar).
To set a set point, push the
SELECT
button until the desired
SET
PT
LED
is flashing. The display
will indicate the current value of the set point. Use the
RAISE
and
LOWER
buttons to adjust the set
point to the desired value. As the indication changes, you will hear short ‘chirps’ from the loud-
speaker.
NOTE:
When using the
SELECT
button, the display will remain in the selected func-
tion until the
SELECT
button is pushed again; or if no button is pushed for 60
seconds, the instrument will revert to normal operation. This automatic reset
is to prevent any error to process control if the instrument is left in the adjust
mode.
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