Emerson Process Management ControlWave EFM 3808 - Manual (Page 215)

CI-ControlWave EFM Appendix F / F- 15
entering a new value. When the mode is changed back to Automatic, the valve control
starts from the last Manual value entered for Bumpless transfer.
If the user selects Raise Lower Mode, the DO associated with raising the valve must be
selected and a separate DO must be selected for lowering the valve. When the Raise Lower
Mode is being used, the Current Data section will display if the Raise DO is Off’ or Raising
and it will display the Lower DO state, i.e., Off or Lowering.
In the Manual Control mode, users may select whether to Raise or Lower the valve by using
the Manual Raise or Manual Lower Output buttons. If the valve is raising and the operator
pushes the Manual Lower Output button, the Raise Output will be automatically set to Off.
If the valve is lowering and the Manual Raise Output button, is pressed, the Lower DO
will automatically be set Off.
When switching back and forth between the Automatic and Manual Modes, both Raise and
Lower DOs will be set to Off.
F.5.6 Run Switching
Sections F.5.6.1 and F.5.6.2 provide information on run switching properties (see Figure F-
10). Enable/Disable Run Switching via a button to the right of Run Switching.
F.5.6.1 Common Properties
Current Rank shows how many runs are required to be open. Maximum Rank is selected by
the user (from 2 to 4). Process Variable (PV) Selection can be Differential Pressure,
Frequency or Flow Rate. The Transition Time is the amount of time required to allow run
switching to access (opening or closing a run). Valve Settle Time is the amount of time
allowed after the Transition Time for the process variable (PV) to settle, before allowing
another run switching action to occur.
F.5.6.2 Run1/2/3/4 Properties
When a run is in Manual Mode (selected by the Run Auto/Manual button), the valve may
be opened or closed by right clicking on the field to the right of the Current Valve Command
and toggling the valve. When a run is in Auto Mode and Run Switching is enabled, the
valve is controlled by the run switching logic. If the Target Rank of a run is 1, the valve will
always be open. The Call Next Run Setpoint (SP) is the value if the process variable (DP,
Frequency or Flow Rate) that will cause the next run to open. The process variable for
calling runs is the PV from the run selected as Target Rank 1. If the run with Target Rank
1 is open, and the run with Target Rank 2 is not open when the PV for Target Rank 1
exceeds the Call Next Run SP, the Target Rank 2 will be opened. Likewise, if the PV for
Target Rank 2 drops below the Call Prev Run SP, the highest ranked run that is open will
be closed.
Call Next Deadband is the amount of time that the PV has to be greater than the Call Next
Run SP value before the next run will be opened.
Call Previous Deadband is the amount of time that the PV has to be less then the Call Prev
Run SP value before the lowest rank run will be closed.
Valve Control DO Point is the digital output point used for valve control.