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Wizcon for Windows and Internet
High-performance architecture
Wizcon’s client-server architecture uses 32-bit, pre-emptive multitasking
and multi-threading technology to reach a high level of performance and
ensure reliability and data integrity. Wizcon’s kernel, WizPro, serves
as a background task and is composed of a number of modules that are executed
simultaneously to provide reliable, real-time data collection and processing.
Each module performs its own processing. The major modules include the
following:
Communication drivers
Separate drivers for each communication link allow Wizcon to communicate
with up to 16 networks of PLCs, controllers, I/O, or other field devices
at the same time.
Alarm generation
A dedicated module that evaluates alarm conditions and issues alarms
locally or across the network immediately when an alarm condition is true.
History logger
This module is responsible for logging tag values and alarms into
historical files.
Printer
This module sends alarm information, user commands and reports to
the printer.
Network
Modules for handling network sessions with other Wizcon stations.
As Figure 2 shows, WizPro handles the Real-Time Database (RTDB) that
includes tag and alarm definitions, as well as communication drivers.
Windows-based applications and Web-based applications use the same RTDB
and other services WizPro provides. Web-based SCADA applications also
use the services provided by the Web server and the Wizcon server. The
Web server handles regular file transfer operations, while the Wizcon
server transfers real-time and historical data upon the browser’s request.
The browser requests an HTML file from the Web server. The server loads the requested HTML page together with embedded Java applets into the browser. The Java applets in turn communicate with the Wizcon server to receive online data, such as changes of tag values, alarms, trend charts, historical information reports and so on.
Tag definitions
Tags in Wizcon refer to control values monitored by the system. Each tag
is identified by a unique name and can be one of several data types (integer,
real, digital, and string). Tags are associated with external device components,
such as registers or I/O points in PLCs and can be defined online. Once
users define tags in the Wizcon tag definition module, they can use them
in other modules for displaying, calculating and controlling functions.
Tag values can also be saved in historical files.
Alarm definitions
An alarm is a test on a tag value that generates a text message when the
condition is true. Alarm application messages are used to notify operators
of exception conditions in the plant. Alarms are automatically available
network wide and can be used in images associated with any type of graphical
object.
In addition, Wizcon generates system messages that provide operators
with information concerning internal system events, such as communication
drivers’ failure, network communication errors, and others.
Event-driven data exchange
The information exchange between Wizcon modules is event-driven. The server
sends only new or updated data to its client, upon request. For example,
when WizPro samples a tag, and the tag value is changed, then the server
sends the new value to the modules that are requesting the tag.
A variety of Wizcon drivers
Wizcon includes over 100 communication drivers for connecting to different
field devices. In addition, Wizcon includes a Communication Drivers Developer’s
kit that enables C programmers to write specific communication drivers
for any proprietary system.
Wizcon is fully compliant with OPC standards for Data Access V2.0. Standard OPC definitions such as server browsing and time stamp support are included. Wizcon’s support for OPC client and server interface ensures that the user can connect to any OPC–enabled application.
