INFICON SQM-242 Thin Film Deposition Controller Card Operating Manual - Manual (Page 32)

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SQM-242 Operating Manual
Perhaps you want to control a backfill gas during deposition. You can use an
analog input to measure pressure from a manometer, and the control output to
drive a gas flow valve. You can still use one or more quartz sensors to measure
and control deposition of your EBeam or thermal power supply.
In another example, you might want to control deposition rate by controlling
temperature. You can assign an analog input to a control output measure and
control temperate, then use a quartz sensor as a final thickness setpoint monitor.
If you select a sensor or analog input that is already assigned to another output, an
error message will be displayed when you try to update the configuration. You will
have the choice of abandoning the change, or overriding the previous
configuration. Your choice could leave a control output with no inputs. In that case,
output power is fixed at 0%.
NOTE: The sensor or analog input selected does not have to be on the same
SQM-242 or SAM-242 card as the control output.
Full Scale . . . . . . . . . . . . . . . . . . . . The output voltage that corresponds to 100%
output power. Full scale values to +/-10 volts
are possible. The full scale output voltage is
a function of your power supply input
specifications.
Max Power . . . . . . . . . . . . . . . . . . . The maximum output power allowed for an
output, in percent of full power. This limits the
maximum % of Full Scale voltage that will be
sent to the source supply.
NOTE: In Simulate mode at least 55%
power is required to simulate
deposition. This simulates a
minimum power that might be
required to vaporize a material.
Slew Rate . . . . . . . . . . . . . . . . . . . . The maximum % Full Scale power change,
per second, allowed on an output during PID
control.
P Term . . . . . . . . . . . . . . . . . . . . . . . The proportional term sets the gain of the
control loop. High gains yield more
responsive, but potentially unstable, loops.
Try a value of 25, then gradually
increase/decrease the value to respond as
desired to step changes in the rate setpoint.
I Term . . . . . . . . . . . . . . . . . . . . . . . The integral term controls the time constant
of the loop. A small I term, say .5 to 1
seconds, will smooth the response and
minimize overshoot to step changes.