Internal Word Data Point Tag

Help Contents

Introduction

The Internal Word Data Point Tag Word Tag Icon stores a 16-bit unsigned integer value internally in the Fernhill SCADA Server.

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

Configuration Properties

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

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

ApplyInitialValueRules
Never
  1. The InitialValue property is ignored.
  2. New tags created by copying an existing tag will be initialized with a value of 0 (zero) and bad quality.
  3. If the Fernhill SCADA Server is restarted, the value of the tag is preserved.
If no value written
  1. If there has been no "Data Write" to the tag, the tag gets its value from the InitialValue property.
  2. Changes to the InitialValue property will update the value of the tag until the first "Data Write".
  3. After the first "Data Write", changes to the InitialValue property have no effect.
  4. New tags created by copying an existing tag will be initialized with the InitialValue property and good quality.
  5. If the Fernhill SCADA Server is restarted, rules 1 to 3 apply.
On server start
  1. If there has been no "Data Write" to the tag, the tag gets its value from the InitialValue property.
  2. Changes to the InitialValue property will update the value of the tag until the first "Data Write".
  3. After the first "Data Write", changes to the InitialValue property have no effect.
  4. New tags created by copying an existing tag will be initialized with the InitialValue property and good quality.
  5. If the Fernhill SCADA Server is restarted, the tag is reset to the InitialValue property.

Note: In the above table, a "Data Write" includes:

Dynamic Properties

The Internal Word Data Point Tag supports the dynamic properties of the Word Data Point Tag.

Tag Commands

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

Tag Command Version Description
WriteValue 1.0 Writes a new value to the tag.
WriteValueQuality 1.0 Writes a new value and quality to the tag.

Relationships to Other Tag Types

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

Further Information

Word Data Point Tag

To learn about properties common to all Word Tags.

Core Driver

To learn about the Core Data Driver.

Glossary

For the meaning of terms used in Fernhill SCADA.