InduSoft Web Studio - InduSoft Corporation

InduSoft Web Studio
Tutorial training – Revision B – Sep/10/2000
© Copyright InduSoft Ltd. 2000
Internal, Application, and Shared Tags
Internal Tags
Internal tags are predefined and perform specific functions within InduSoft Web Studio’s
supervisory tasks. Most internal tags are read-only. To change the time, for instance, use the
proper math function rather than writing to the internal time tag.
Examples: Date holds the current date in string format and Time holds the current time in string
format.
Application Tags
Application tags are created by the user during application development (for example: displays,
tags that read from and write to field equipment, tags used for control, auxiliary tags to perform
mathematical calculations, and so forth).
Shared Tags
These are tags read from another software package (generally a PC-based control software
package). These tags cannot be edited from Indusoft Web Studio.
Database Exercise
In the Workspace window, select the Database tab. Click the Application Tags folder to expand it
and double-click the Datasheet View line to open the database worksheet.
The database may be updated during the development so that new tags may appear as they are
created. We can also define tags that we already know we will need at the beginning of our
application. The first tags contain values for the state of the valves that fill or empty the tanks
(Valve_Fill_State and Valve_Empty_State). Each valve has only two possible states
(opened or closed), so a tag associated with these valves should be a Boolean tag. There will be
three tanks in the application, each configured similarly, and there are two types of valves: one to
fill and one to empty each tank. We can use arrays to quickly configure the tags associated with
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