Vijeo Citect Technical Overview - Square D

Open to anyone
While using Schneider Electric controllers will provide
the best possible results with your Vijeo Citect
system, we recognize that communication to a wide
range of controllers is the key to ensuring a complete
view of your control system. To accommodate
communication with these controllers, a collection
of over 150 protocol drivers are included within Vijeo
Citect.
Vijeo Citect’s open connectivity from various
information systems allows seamless dataflow,
promising real-time and rich process information.
Vijeo Citect has the flexibility to operate with open
standards supported by hundreds of hardware and
software vendors.
Maximize data transfer
Vijeo Citect recognizes that many I/O devices can be
slow and inefficient when responding to requests for
data. The following strategies allow Vijeo Citect to
maximize data transfer.
Vijeo Citect’s communication is demand based —
reading only those points which are requested by the
clients. More importantly, the I/O server rationalizes
requests from clients, for example, combining them
into one request where possible. This reduces
needless communication, giving screen update times
of up to eight times faster than without it.
Only a restricted volume of data can be returned in
one request. If all requested data is grouped together,
then fewer requests are required and the response is
faster. By compiling a list of the registers that must be
read in one scan, Vijeo Citect automatically calculates
the most efficient way of reading the data.
Vijeo Citect’s client-server processing allows further
performance increases, through the use of a cache
on the I/O server. When an I/O server reads registers,
their values are retained in its memory for a user
defined period (default 300ms). If a client requests
data that is stored in the cache, the data is provided
without the register being re-read. In a typical twoclient
system, this usually occurs 30% of the time,
resulting in a potential 30% increase in performance.
Seamless dataflow: Our open connectivity to various information systems.
Seamless dataflow; our open connectivity to various information systems
Reliable
Performance
Vijeo Citect’s distributed
processing and network
optimization give you
excellent network
performance, even when
you have over 450,000
I/O and 60 Vijeo Citect
computer stations:
Relative load
VIJEO CITECT
Network Load Vs System Size
1
10
100
1000
I/O
1
10000
100000
IDEAL
Network Limit
20
15
10
5 Nodes
Without Vijeo Citect’s
network optimization,
you can expect network
load to increase
dramatically, ‘choking’
as you add more I/O
and computer stations:
Relative load
1
10
Communication
Other SCADA Systems
Network Load Vs System Size
Network Limit
20
15
10
Nodes
5
100
1
1000
10000
I/O
100000
UNACCEPTABLE
17