Distributed
systems in WinCC OA
allow to connect two or more autonomous WinCC OA
systems via a network. Each sub system of a distributed system
can be configured either as single-station system or multiple-station
system in each case redundant or not redundant. A sub system means
in this connection a server on which an Event manager is running
on (this means not necessarily a complete project). In a redundant
system both redundant running servers are considered as one system.
The
distributed systems in WinCC OA
are intended for supporting following problems:
Connecting
several stand-alone WinCC OA
systems Increased performance (increase
of the entire performance and number of the DPEs via load
sharing on several computers) 1 central system and "unoccupied"
subsystems
Each
system can process and display data (values and alerts) of other
systems. You can also access online values, alerts and history
of each system by using distributed systems in WinCC OA ("distributed
database"). When you access remote DPEs the data points of
the sub systems are not copied to the local system. This means
that the data points are not multiplied and you can only access
the system when a connection to this specific system exists.
The
distribution manager (shortly
referred to as Dist manager) builds the interface to other systems.
Only the Dist manager is responsible for the communication with
the configured sub systems. Thus, the Dist manager has to be added
to the console and started for the proper functionality of the
distributed systems in WinCC OA.
The
distributed systems are configured easily when creating a project
by using a wizard (see Create
a distributed system) or by specifying few entries in the
config file of your project (see Configuration
file for distributed systems).
The following figure shows a possible structure
of several WinCC OA
systems connected to each other.
Figure: Distributed systems with
WinCC OA
The figure shows a distributed
system consisting of a redundant system (System 1), a multiple-station
system (System 2) and a single station system (System 3).
Each system may have an
own process connection (PLC, DDC, telecontrol head). All process data is mapped
to data points local (in the own system). In a plant display data
points of the local as well as of the connected systems can
be shown. The network connection between
the systems can be redundant. You can connect 2048 systems. A weighting can be assigned
to errors occurring in a sub system. The weighting i.e. how
grave the error is for the specific system is configured by
the user (examples of errors can be: Crash of manager, loss
of a network connection in case of redundant networks, computer
breakdown, ...). Also a possible loss of a connection to a
sub system may have an assigned error weighting (like a PLC
breakdown). The weightings for error cases are configured
in the System
overview panel for distributed systems.
Advantages of distributed systems in WinCC OA:
Flexibility and scalability Increased performance: parallel
processing, load sharing Fault tolerance: availability
increase of the complete system Complete identical systems
(data point types and data points) have to be configured only
once , for example, create the panels and reference the data
points with $ parameters only once
The following chapters give you important information
about how to create a distributed system with WinCC OA
as well as show examples of how to configure the error weighting. |
