External items

In order for the Apis modules to exchange values, the items defined in Apis may have an attribute called ExternalItem. Exchanging values in the Apis context simply means copying the value of one item from one module to another item (typically in another module).

The ExternalItem attribute(s) is a string that contains the name of the item whose value is to be retrieved. It is always the item that receives the value from another item that defines the external item.

The external item feature in Apis may be utilised in many ways. In addition to raw copy of the value from an external item, functionality such as data validation and pulse trigging is available. Confer the linked topics below for a detailed description.

• External Item data transfer control
• External item data validation
• External item monitoring - pulse trigger