String Data Tag

Introduction

The String Data Tag String tag icon represents a variable length string data tag with a maximum length of 160 characters.

Configuration Properties

The String Data Tag supports the properties of the Core Tag plus these properties:

Property Type Version Description
NormalColor STRING 3.1 The value of the Color property when the tag is normal quality.
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.

Dynamic Properties

The String Data Tag supports these dynamic properties:

Property Type Version Description
Value WSTRING[160] 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)
UnforcedValue WSTRING[160] 1.2 The current value of the tag when this tag has been forced to a fixed value
UnforcedQuality INT 1.2 The quality of the current value when this tag has been forced to a fixed value
UnforcedTimestamp DATE_AND_TIME 1.2 The timestamp of the last update when this tag has been forced to a fixed value
UnforcedColor DWORD 1.2 The color of the tag when this tag has been forced to a fixed value
ErrorCode USINT 1.2 The status of the last update to the tag's value. A non-zero value indicates an error.
DataSource WSTRING 2.0 The data source of the tag.
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 (read only).

Color Property

The Color property provides an indication of the state of the tag using color:

Tag StateConditionColor Value
The tag is forced IsForced = True The ForcedColor defined in the Database Root Tag
The quality is bad Quality < 192 The BadQualityColor defined in the Database Root Tag
Otherwise The NormalColor defined above.

TagErrorCode Property

When the Quality of the tag data is 'Bad', the TagErrorCode property indicates the reason for the error:

ErrorCodeDescription
0No error.
1The tag is not associated with a valid data source.
2The tag's data source reference is valid, but the data source has a configuration error.
3The offset of the tag is outside the boundary of the data source.
4The data type is String, but the source value is not a valid string.
5There was an error converting the data.

Tag Commands

A tag command is an action you can trigger on a tag. The String Data Tag supports these tag commands:

Tag Command Version Description
ForceValue 1.2 Applies a force to the tag in Fernhill SCADA to mask the actual value read from the data source.
RemoveForce 1.2 If a force is active on the Tag in Fernhill SCADA, it is removed and the actual value from the data source is restored.

Relationships to Other Tag Types

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

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

Further Information

Core Tag

To learn about properties common to all tags.

Data Tag

To learn about other types of data tag.

Glossary

For definitions of the terms used in Fernhill SCADA.