Function Block Properties dialog box - Cascade/Ratio tab (PIDE, IMC)
The Cascade/Ratio mode can be controlled by a user program when in Program control or by an operator interface when in Operator control. While in Cascade/Ratio mode the instruction computes the change in the control variable (CV). The instruction regulates CV to maintain the process variables (PV) at either the cascade value or the cascade value multiplied by the ratio value.
This property can be set for both Enhanced Proportional Integral Derivative (PIDE) and Internal Model Control (IMC) instruction function blocks.
Use the
Cascade/Ratio
tab to set the parameter values for the selected function block.The following table describes the parameters available on the
Cascade/Ratio
tab:Parameter | Description |
Allow Cascade/Ratio mode | Sets the value of the AllowCasRat parameter. If checked, this value is set to 1; otherwise, it is set to 0. |
Use Ratio | Sets the value of the UseRatio parameter. If checked, this value is set to 1; otherwise, it is set to 0. |
Ratio HLimit | Sets the value of the RatioHLimit parameter. |
Ratio LLimit | Sets the value of the RatioLLimit parameter. |
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 will 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. |
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. |
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