CASCADE_SLAVE is a module template similar to the PID_LOOP template. It includes several module level connection parameters for communication with the module created from the CASCADE_MASTER template. All seven alarm parameters in CASCADE_SLAVE are disabled as a default.
When the module library is used to create a cascade control strategy, a module must be created from each of two module templates, CASCADE_MASTER and CASCADE_SLAVE. Start with CASCADE_SLAVE.
The CASCADE_SLAVE module template is part of the CASCADE_MASTER template. To configure the slave loop from the CASCADE_SLAVE template, expand the CASCADE_MASTER template and drag and drop the CASCADE_SLAVE template to the target area.
|
Parameter |
Description |
|---|---|
|
CONTROL_OPTS |
The only control option enabled as a default is SP-PV Track in Man. Other control options to consider are SP-PV Track in LO or IMan, Track Enable, and Track in Manual. When SP-PV Track in Man is disabled, you might want to enable the option to Use PV for BKCAL_OUT. |
|
GAIN |
Proportional gain tuning parameter. The default is 0.5. Default tuning in CASCADE_SLAVE is set conservatively for a typical flow loop. |
|
IO_IN |
An I/O Reference parameter for configuring the DST for the process variable input. |
|
IO_OPTS |
None of the IO options are initially enabled. In the PID block, IO_OPTS is used to select the Increase to Close option for the control output (for example, for a fail open valve), or to enable the low cut-off function for the process variable input. |
|
IO_OUT |
An I/O Reference parameter for configuring the DST for the control output. |
|
L_TYPE |
Linearization type. The default is Indirect. This might be changed to Ind Sqr Root, for example, when flow is being determined from differential pressure. |
|
PV_SCALE |
This parameter is used to set the engineering unit value at 0 percent and 100 percent of scale for the process variable. The engineering unit descriptor can be selected from a list and the number of decimal places to be displayed can be set. Note that the number of decimal places to be displayed is applicable only for the faceplate and detail displays. The valid values for these displays are 0 to 3 decimal places. |
|
RESET |
The integral time constant tuning parameter in seconds (seconds per repeat). The default is 5 seconds. Default tuning in CASCADE_SLAVE is set conservatively for a typical flow loop. |
|
SP_HI_LIM |
The high limit for the setpoint. Typically, this value should be changed when the EU 100 percent value is changed from the default in PV_SCALE. |
|
SP_LO_LIM |
The low limit for the setpoint. Typically, this value should be changed when the EU 0 percent value is changed from the default in PV_SCALE. |