Define invariant and revertible parameters

While in the Model Writing role, you can choose between the following options for how parameters behave when you revert a simulation to a captured snapshot:

• Locked: The parameter never changes value or badging. This is the default parameter type and is suitable for most parameters.

• Invariant: The parameter does not change value or badging unless you include invariant objects in the reversion. See Return to previously specified invariant values for more information.

• Revertible: The parameter changes value and badging to match the value from the snapshot. Currently, this option affects only Integer, Enumeration, and Real parameters. If you inadvertently define other types of parameters as revertible, the software treats them as locked parameters.

This behavior applies to both Model Writers and Simulation Builders.

Typically, parameters that do not change with operating conditions are good candidates for invariant parameters. For example, the pipe size and schedule do not change with operating conditions. You may want to define the pipe size and schedule as invariant parameters. In this case, you can test the effect of changes in the pipe size and schedule and revert back to the snapshot values if you don't like the results.

Parameters that represent an operating state or a modeling state that depends on operating conditions are good candidates for revertible parameters. For example, the Operation parameter for a PID controller determines whether the PID controller operates in Auto or Manual mode, which affects the variables related to the PID controller. If you revert the simulation to a captured snapshot, these variable values may not match the snapshot values if the Operation parameter does not also match the snapshot values. Therefore, we define the Operation parameter as a revertible parameter.

If a Model Type has connections that include any invariant or revertible parameters, AVEVA Process Simulation treats all parameters in the connection as invariant or revertible parameters.

Currently, you can define only Integer, Enumeration, or Real parameters as invariant or revertible parameters.

Define a parameter as an invariant parameter

1. Ensure that the Model Writing role is selected. See Roles, Roles.

2. Open the Model Editor for the desired Model Type.

3. Expand the Parameters section.

4. Select the Invariant icon to flag the parameter as an invariant parameter .

   Selecting the Invariant icon multiple times cycles through the locked , invariant , and revertible selections.

Define a parameter as a revertible parameter

5. Ensure that the Model Writing role is selected. See Roles, Roles.

6. Open the Model Editor for the desired Model Type.

7. Expand the Parameters section.

8. Select the Invariant icon twice to flag the parameter as a revertible parameter .

   Selecting the Invariant icon multiple times cycles through the locked , invariant , and revertible selections.