A variable tag is a representation of data elements. Each element provides access to a view of the data value for the tag.
Each variable tag can be used on its own or by referencing a particular element to access the following information:
|
Element |
Description |
|---|---|
|
.field |
The field element, which represents the latest field data received from the device. |
|
.valid |
The valid element, which represents the last field data which had ‘Good’ quality. |
|
.override |
The override element, which represents the overridden tag value. |
|
.overridemode |
The override mode, which is used to set the override behavior of the tag. |
|
.controlmode |
The control mode, which is used to set the control inhibit mode of the tag. |
|
.status |
The tag status element, which is used to represent the current status of the tag. |
The tag and each element have items that can be referenced to access the following information:
|
Item |
Description |
|---|---|
|
v |
The value item. Use this to retrieve the current data value of the tag or element. |
|
vt |
The value timestamp item. Use this to retrieve a timestamp that represents when the value last changed. |
|
q |
The quality item. Use this to retrieve the quality of the value. The quality item differs to other elements as it offers several layers of information. For more information, see The Quality Item. |
|
qt |
The quality timestamp item. Use this to retrieve a timestamp that represents when the quality last changed. |
|
t |
The timestamp item. This will access the timestamp of when the tag or element was last updated. |
To refer to tag elements in your project, you use Tag Extensions.
Published June 2018