Common Data Tag

Introduction

A Data Tag stores a single data value with an associated quality and timestamp.

These data tags are supported:

Icon Tag Type Version Description
Analog tag Analog Data Tag 1.0 A floating point value.
Digital tag Digital Data Tag 1.0 A single bit or boolean value.
Double word tag Double Word Data Tag 1.3 A 32 bit word value.
String tag String Data Tag 1.2 A string value.
Word Data Tag Word Data Tag 1.2 A 16 bit integer value.

Common Configuration

All types of data tag support these common configuration fields:

Property Type Version Description
AllowForce BOOL 3.21 Whether the user can force the tag's value to a fixed constant value.
HistoricEnable BOOL 2.5 Whether the value of the tag is stored historically.
HistoricSampleInterval TIME 2.5 The maximum interval between consecutive values recorded in the history.
HistoricSampleCount UDINT 2.5 The number of sample values to retain in the historian.

Common Attributes

All types of data tag support these common attributes:

Property Type Version Description
Value ** See Note 1.2 The current value of the tag
Quality INT 1.2 The quality of the current value
Timestamp DATE_AND_TIME 1.2 The timestamp of the last update to this tag
Color DWORD 1.2 Indicates the state of the tag using color
IsForced BOOL 1.2 Indicates whether the tag has been forced (true), or not forced (false)
DataSource WSTRING 2.0 A string describing where the tag data originates from.
DisplayValue WSTRING 2.5 The display value of the tag.
HistoricDataTable STRING 2.5 The name of the database table used to store historic values for this tag.

Note: The type of the value field depends on the type of the tag.

Relationships to Other Tag Types

The Data Tag builds on the features of these tag types:

The Data Tag is used as a building block for these tag types:

Further Information

Glossary

For definitions of the terms used in Fernhill SCADA.