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Optional Input Plot Page:
Notes: The key parameters for tuning an Optional input pressure response is Opt_kp and ki.
Opt_imin _offset is a factor that is applied to the valve command minimum (valve current starting
point) to effectively lower the command min by the value of the offset. For example, an
Opt_imin_offset of 15, the default, would shift the valve command minimum down by 15 mA.
In some pressure control circumstance, normally associated with trying to control to very low at
optional input set points (trying to control at very low pressures) the following condition can occur:
MFC command min (valve starting point in flash memory) > valve_cmd at set point (valve mA
at steady state for a given set point)
If this condition is true, the MFC is going to essentially start at a higher current than necessary to
actually achieve set point and the response is going to overshoot when the set point is initiated. This
parameter can be used to correct overshoot in this very special circumstance.
The default value, 15, should be adequate for the majority of optional input control scenarios and
does not need to be changed for the application.
Optional Input Plot Page Example
• Pressure control data collected, saved from the plot page, and transferred into an excel
spreadsheet is presented in the graph below: