Technical Reference Manual - InduSoft

Introduction
Internal structure and data flow
The InduSoft Web Studio project runtime runs on a Windows computer or embedded system and consists
of the following modules or threads (program elements that can execute independently of other program
elements):
• Background Task (a supervisory task): Executes other internal tasks (IWS worksheets). For example,
the Background task executes scripts configured in the Math and Scheduler worksheets and manages
parameters configured in the Alarm, Recipe, Report, and Trend worksheets.
• Database Spy (debugging tool):
• Executes functions and/or expressions for testing purposes
• Reads data (such as tag values) from the tags database
• Writes data (such as tag values) to the Tagsdatabase
• DDE Client: Manages DDE communication with a DDE Server (local or remote), according to parameters
configured in the DDE Client worksheets.
• DDE Server: Manages DDE communication with a DDE Client (local or remote).
• LogWin (debugging tool): Traces messages generated from other modules/tasks.
• Driver Runtime: Manages the read/write commands configured in the Driver worksheets.
• OPC Client: Manages OPC communication with an OPC Server (local or remote), according to parameters
configured in the OPC Client worksheets.
• OPC Server: Manages OPC communication with an OPC Client (local or remote).
• ODBC Runtime: Manages ODBC data communication with any SQL relational database, according to
parameters configured in the ODBC worksheets.
• TCP/IP Client: Manages TCP/IP communication with a remote TCP/IP Server module (from IWS),
according to parameters configured in the TCP/IP Client worksheets.
• TCP/IP Server: Manages TCP/IP communication messages with a remote TCP/IP Client module (from
IWS).
• Viewer: Executes all scripts (On Open, On While, On Close, Command, Hyperlink, and so forth) configured
for project screens and updates the screen objects.
None of the preceding runtime modules exchange data directly with another module or task. Instead, runtime
modules send data to and receive data from the tags database, which is the "heart" of IWS.
The tags database manages the flow of data between modules. In addition, the tags database stores all tag
values and the status of all properties associated with each tag (such as alarm conditioning, timestamp,
quality, and so forth).
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