Alarms and events

Create a custom calculation for the alarm

Custom alarm calculations must be associated with a parameter that has a value of either 0 or 1. A one (1) indicates an alarm condition, and a 0 indicates a non-alarm condition.

Note

If you create your own alarm calculations you must use one of the function blocks that support expressions (for example, the Condition function block or the Calc/Logic function block).

The following example shows how to add a custom alarm to a module using a Condition block. In this example, an alarm is triggered when the PV of the AI block is 70 or higher.

Note

The custom calculation creates a Boolean parameter that still must be associated with the alarm. This step only sets up the calculation that is associated with an alarm.

To create a custom calculation, perform the following steps:

  1. Drag an Analog Input block onto the diagram. The Analog Input block is in the I/O function block category.
  2. Drag a Condition block onto the diagram. The Condition block is in the Logical function block category.
  3. Right-click the Condition block.
  4. Select Expression.
  5. In the Expression Editor dialog, click Insert Internal Parameter.
  6. Browse to the AI block's PV parameter and CV field. 
  7. Click OK.
  8. In the Expression Editor dialog, click the >= symbol.
  9. Enter the value 70.
  10. Click Parse.
  11. When the expression parses without any errors, click OK.

This sets up an expression to see if the PV parameter is greater than or equal to 70. For this module, the value of the expression is the value of the OUT_D parameter.