INFICON Crystal 12 Sensor - Manual (Page 37)

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Crystal12 Sensor Operating Manual
2.5 Crystal12 Operation when
used with a Cygnus
2.5.1 Initialization
An automatic Rotate Head function occurs when the Cygnus is first powered on,
assuming that a channel's crystal Sensor Type is configured as a Crystal12.
HINT: It is important to perform a Rotate Head function after a carousel
change-out, or after changing the crystal sensor type.
Whenever a Rotate Head function is initiated, the Cygnus will advance the Crystal
12 carousel until it locates Position 1. After Position 1 is located, the Rotate Head
function begins cataloging the crystals at each position as either good or failed.
Š Because Position 1 is unique, the Crystal 12 always ends on Position 1.
Š A Rotate Head function could require as many as 11 pulses to initially find
position 1 and an additional 12 pulses to catalog the crystals (total maximum
number of pulses for initialization is 23).
Š A Rotate Head function can only be done when the Channel is in READY or
STOP state.
A Crystal Switch will also identify a crystal in the new position as either "good" or
"failed".
Because only Position 1 is uniquely identified, if the Crystal 12 is manually moved
we do not guarantee correct position detection.
Š Example 1. If the Crystal 12 head were moved manually from Position 2 to
Position 5, Cygnus would not detect the difference. When a switch is done,
Cygnus would advance the Crystal 12 to Position 6, and assume it was Position
3 as these two positions are not uniquely identified.
Š Example 2. Once a position is reached, Cygnus assumes the Crystal 12
remains on that position until a Crystal Switch or a Rotate Head function is
initiated.
2.5.2 Crystal Switching
A Crystal 12 requires one pneumatic pulse to change position. Upon a crystal
switch, the Crystal Switch Output relay will close for one second and then open.
One second after the relay is opened, the crystal switch function is considered
complete. Cygnus then looks for the appropriate crystal position.
After completion of the crystal switch, there is a short delay of about 5 seconds
before the crystal frequency information is used. This delay insures good frequency
reading by allowing time for the crystal to come to thermal equilibrium after being
exposed to the material source.