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.
When you configure an equipment type, it is 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 Citect SCADA Example project includes an equipment type named "Motor". It includes the following items:
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 naming an Item, there are a number of reserved words that you need to avoid. These reserved words relate to syntax that is used for tag extensions. They are:
• field
• valid
• override
• overridemode
• controlmode
• status
• v
• vt
• q
• qt
• t
If you use one of these reserved words, an error message will display when you compile your project.
See Also:
Published June 2018