Internal Double Word Data Point Tag

Help Contents

Introduction

The Internal Double Word Data Point Tag Double Word Tag Icon stores a 32-bit unsigned integer value internally in the Fernhill SCADA Server.

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

Configuration Properties

The Internal Double Word Data Point Tag supports the configuration properties of the Double Word Data Point 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 DWORD 3.13 The initial value of the tag.
ShowWriteValue BOOL 3.34 Whether to show the WriteValue Tag Command in the Standard Tag Menu.
ShowWriteValueQuality BOOL 3.34 Whether to show the WriteValueQuality Tag Command in the Standard Tag Menu.

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 0 (zero) 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 Double Word Data Point Tag supports the dynamic properties of the Double Word Data Point Tag.

Tag Commands

The Internal Double Word Data Point Tag supports tag commands of the Double Word Data Point Tag plus these tag commands:

Tag Command Version Description
WriteValue 1.3 Writes a new value to the tag.
WriteValueQuality 1.3 Writes a new value and quality to the tag.

Relationships to Other Tag Types

The Internal Double Word Data Point Tag builds on the features of these tag types:

Further Information

Double Word Data Point Tag

To learn about properties common to all Double Word Tags.

Core Driver

To learn about the Core Data Driver.

Glossary

For the meaning of terms used in Fernhill SCADA.