INFICON IC/5 Thin Film Deposition Controller - Manual (Page 223)

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IC/5 Operating Manual
Figure 10-12 Statement 7
This statement monitors the Evacuate Chamber input and the status of Timer 8.
Timer 8 is set in Statement 23 to indicate the Alarm Answered input has been
activated (i.e., the alarm has been answered). Therefore, automatic processing
cannot proceed unless the Evacuate Chamber and the Alarm Answered inputs are
initiated and the conditions of Statement 3 are satisfied. Statements 7 and 8 are
very similar however they differ by monitoring the status of the Crossover pressure
input. If the Crossover pressure has not been achieved, the foreline and high
vacuum valves are closed and timers 2 and 3 are set. These timers are used in
Statements 9and10 to delay the opening and closing of the roughing valve. This is
done to prevent a pressure burst through the diffusion pump and foreline. Timer 8
is immediately canceled so that Statement 7 is always dependent on the Alarm
Answered input being initiated.
Figure 10-13 Statement 8
Statement 8 differs from Statement 7 in the status of the Crossover pressure input.
If the chamber Crossover pressure is reached, timer 5 is set for 20 seconds. The
vacuum system at this point has the Roughing, High Vacuum, and Vent Valves
closed and the Foreline Valve open. Timer 5 is used as a delay prior to opening the
High Vacuum Valve.
Figure 10-14 Statement 9
By its dependency on Timer 2, Statement 9 is tied to Statement 7. If the chamber
is not at the Crossover pressure the roughing valve will be open to pump down to
the Crossover pressure. The dependency on the Foreline Valve closed input is to
insure the foreline valve is closed prior to opening the Roughing valve. Timer 2 is
immediately canceled so that Statement 9 is evaluated true only once each time
Statement 7 is true.
Figure 10-15 Statement 10