Items

The term "item" is used to describe a particular attribute of a physical piece of equipment that is represented in an equipment definition.

Items can be used to reflect different aspects of a piece of equipment, such as an associated action, condition or setting. They group the tags associated with equipment in a way that allows you to reference the particular attribute the item represents.

Equipment Types are defined as a set of items. Each item includes a number of elements that directly link to the physical device, such as variable tags, trends or alarms.

Example

The Plant SCADA Example project includes an equipment type named "Motor". It includes the following items:

• Running

• Stopped

• Auto

• OutOfService

• Alert

• IntLock

• Start

• Stop

• IntBypass

• Reset

• FailStart

• FailStop

This list demonstrates the different types of attributes you can represent with an item, including operational states (Running, Stopped), actions (Start, Stop, Reset), alarm conditions (FailStart, FailStop) and settings (IntBypass).

In each case, the item is made up of a set of elements (tags, trends and alarms) that enable interaction with the physical device.

For example, FailStart includes a variable tag definition that is associated with the physical motor, and a digital alarm tag that indicates when an attempt to start the motor has been unsuccessful.

Note: When defining an item name, avoid using Reserved Words. If you use any of these, an error message will display when you compile your project.

See Also

Equipment Instances