Sometimes, not all instances of a control module class are identical, or there are particular parameters that should be handled differently on different modules. To allow for these minor differences, you can define specific parameters as being configurable at the instance level. (Not all parameters have properties that can be modified.) Then, when you create the instances, you can change the configurable parameter values as needed. To do this, you also need to clear the Properties dialog check box for the instance parameter, Use default value from library object. Clearing the check box breaks the link with the class. Note that if you later make changes to configurable parameters at the class level, the changes are propagated to all instances, except for those that have had the link with the class specifically broken. You can reestablish the link with the class by selecting the check box (use default value from library object) again.
If you are planning to use the same Primary Control Display for all or most of the control modules created from a class, you can specify the display using the Properties dialog at the class level. This saves the time of specifying the display for each control module. Assigning the faceplate and detailed display at the class level could also save time. This assignment should be performed before the control module instances are created, since the display names are not propagated to the instances after the control modules are created.
The paint application has a number of normally closed on-off valves with one input and one output parameter. For the purpose of illustration, we will make one of the tuning parameters on the DC block, DELAY_TIME, configurable at the instance level. The DELAY_TIME value for opening the valve is normally 0 but, in some instances, you may want to be able to specify a delay before opening the valve.