INFICON Composer Gas Concentration Controller - Manual (Page 176)

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Composer Operating Manual
8.3.8 Control State
The Control State menu choices under Action item in the menu bar allow
access to control state functions otherwise available through I/O connector at
the rear of the instrument or through keyboard entry on units with display. The
check mark next to the menu item displays the current Control state. The
function of each selection is explained below.
Control . . . . . . . . . . . . . . . . . . . . . It starts the control loop action. If data
collection was not already in progress, it is
initiated as well. Appropriate signals are
sent to connected mass flow controllers to
achieve and maintain desired
concentration level.
Stop . . . . . . . . . . . . . . . . . . . . . . . It terminates control loop action and sets all
control voltages to zero.
Hold . . . . . . . . . . . . . . . . . . . . . . . It holds the control outputs at their current
level. Thus, it is equivalent to open loop
control. This option is unavailable from
Stop, Bypass or Manual state.
Bypass . . . . . . . . . . . . . . . . . . . . . It (in dilution flow mode) sets the bubbler
control voltage to zero and sets the dilution
flow equal to the total flow. Thus, it can be
conveniently used to setup pure carrier gas
flow for precisely establishing zero
frequency.
Manual . . . . . . . . . . . . . . . . . . . . . It brings up a Manual pop up box as shown
in Figure 8-8 . In this mode, the user can
directly manipulate two mass flow
controllers by appropriate entry in the input
boxes and pressing the Set Flow button.
This is a very convenient way to look at the
system dynamics and to estimate process
gain, as defined in
section 8.3.5.6 on page
8-16 . Clicking mouse button anywhere else
on the screen removes this pop up, but
maintains flow settings. Pressing Stop,
Control or Bypass (Hold is unavailable)
terminates Manual state.