Function Block Properties Dialog Box - General Configuration Tab Overview (IMC)

The Internal Model Control (IMC) instruction controls a single process variable by manipulating a single control-variable output. This function block performs an algorithm where the actual error signal is compared against that of an internal first-order lag plus deadtime model of the process. The IMC function block calculates the control variable output (CV) in the Auto mode based on the PV deviation from the set point (SP), internal model, and tuning.
Use the
General Configuration
 tab of the
Function Block Properties
 dialog box to set the values for the parameters of the selected IMC function block.
The following table describes the parameters available on the
General Configuration
tab:
Parameter
Description
Timing
  • Mode
Sets the value of the
TimingMode
 parameter. Supports the following options:
Periodic
 = 0 (default)
Oversampling
= 1
Real Time
 = 2
  • Oversample DeltaSymbolt
Sets the value of the
Oversample
DeltaSymbol
t
 parameter.
This field is only enabled if you chose the
Oversampling
 option for the
TimingMode
 parameter.
Valid values are in the range of 0 to the maximum of the TON_Timer elapsed time (4194.303 sec.)
The default value is 0.
  • RTS Period
Sets the value of the
RTSTime
 parameter.
This field is only enabled if you chose the
Real Time
 option for the
TimingMode
 parameter.
Valid values are in the range of 1...32767 (1 count = 1 millisecond).
Control Variables
  • Use CV Track Value
Select this check box to enable CV Tracking when autotune is set to OFF.
  • CV Track Value
Enter the control variable track values in the range of 0.0...100.0.
The default value is 0.0.
These values are useful in multiloop selection schemes where you want the IMC instruction to follow the output of a different controlling algorithm, where you would connect the output of the controlling algorithm into the CVTrackValue.
The
Use CV Track Values
 check box must be selected for you to enter values in
CV Track Value
.
  • Override Value
Enter the control variable override value fin the range of 0.0...100.0.
The default value is 0.0.
Set this value in Override mode.
These values should correspond to a safe state output of the IMC loop.
  • Program Control Value Reset
Select this check box to reset the program control values.
  • Manual Mode after Initialization
When this check box is selected, the instruction is placed in the Manual mode when CVInitializing is set to TRUE unless the current mode is Override or Hand.
When the check box is not selected, the instruction's mode does not change.
PV Tracking
Select this check box to enable the SP to track the PV.
This control is ignored in CascadeRatio or Auto modes.
Status
Displays status information for blocks containing status bits. If none of the status bits are set, an
OK
 message appears in this field. Otherwise, a list of the status bits that are set appears here. This list is comprised of the parameter names associated with the status bits, and typically explain which parameters were configured with invalid values.
Execution Order
Displays the block's execution number if the routine is in a verified state. If the routine is not yet verified, a
Routine not verified
 message appears. Note that this item is read-only.
Never display description in a routine
Select this check box if you do not want the description to display in the routine.
OK
Click this button to add the selected item in the instruction list to the routine and close the
Function Block Properties
 dialog box.
Cancel
Click this button to cancel any edits you have made and close the
Function Block Properties
 dialog box.
Apply
Click this button to accept your changes and continue editing in the
Function Block Properties
 dialog box.
Provide Feedback
Have questions or feedback about this documentation? Please submit your feedback here.