Internal Digital Data Tag

Introduction

The Internal Digital Data Tag Digital Data Tag Icon stores a digital value with two states internally in the Fernhill SCADA Server.

The Internal Digital Data Tag is a license free tag. You can create any number of these tags without restriction.

Configuration Properties

The Internal Digital Data Tag supports the configuration properties of the Digital Data Tag plus these properties:

Property Type Version Description
ApplyInitialValue USINT 3.13 Specifies when the initial value should be applied to the tag.
Options are: 0 = Never, 1 = If no value written, 2 = On server restart.
InitialValue BOOL 3.13 The initial value of the tag.

ApplyInitialValue Property

The ApplyInitialValue property defines when the initial value is applied to the tag. The options are:

ApplyInitialValueDescription
Never The initial value is never applied to the tag. Changes to the InitialValue field have no effect.
New tags will be initialized with a value of false (off) and bad quality.
New tags include those created by copying existing tags.
If the Fernhill SCADA Server is restarted, the value of the tag is preserved.
If no value written If no value has been written to the tag, the InitialValue field is applied to the tag.
Changes to the InitialValue field will be applied to the tag until the first value is written.
After the first value is written, changes to the InitialValue field have no effect.
New tags created by copying an existing tag will be initialized with the InitialValue and good quality.
If the Fernhill SCADA Server is restarted, the value of the tag is preserved.
On server start If the Fernhill SCADA Server is restarted, the initial value will be written to the tag.
Changes to the InitialValue field will be applied to the tag until the first value is written.
After the first value is written, changes to the InitialValue field have no effect.
New tags created by copying an existing tag will be initialized with the InitialValue and good quality.

Note: Values are written to the tag using one or both of these tag commands:

Dynamic Properties

The Internal Digital Data Tag supports the dynamic properties of the Digital Data Tag.

Tag Commands

The Internal Digital Data Tag supports tag commands of the Digital Data Tag plus these tag commands:

Tag Command Version Description
WriteValue 1.0 Writes a new value to the internal analog tag.
WriteValueQuality1.2 Writes a new value and quality to the internal tag.

Relationships to Other Tag Types

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

Further Information

Digital Data Tag

To learn about properties common to all digital tags.

Core Data Driver

To learn about the Core Driver.

Glossary

For the meaning of terms used in Fernhill SCADA.