6-1: Programming - Variables

Powervision Variables have the following user configured features.

 

Data Invalid

Use this setting if the variable is expected to be periodically updated as in the case of a received CAN variable. If the variable is not refreshed within the allowable time the value will go invalid (Not a Number). 

 

 

You can use this on the display to change a widget to a different color to alert the user. This is found in the widgets data error property.

 

Use the function IsValid() to test the variable in a calculation event, Activity Program, Scripting, or an expression.

 

 

Saving Variables in Non Volatile Memory (Persistent and Retained Variables) 

Variables can be set to retain their value after a power cycle or after the display has been reprogrammed as in the example of an odometer.

Select the desired type then use the action NVmgr->Save-Variable Name to save the value to Flash memory. Writing to Flash memory consumes a lot of resources so be mindful of that when calling this function. 

Note: This only works on Double data types.

 

Simulation Mode/ Test Mode

When the display is in simulation mode or when a Calculation Event is in test mode the min and max values are derived from the variables settings.

Set the desired min and max as well as the step size, this applies to any variable.

Simulation mode can be entered by setting the system variable Setting.SimData to a value of 1. Use this mode for demonstrations or to check the UI design in dynamic mode.