TAC Xenta 555, Supplement Manual
12 Performance Considerations
TAC AB, Oct 2006
77 (82)
04-00054-01-en
12
Performance Considerations
12.1
Network Architecture
The size of a MicroNet/Satchnet network within XBuilder is not lim-
ited. It is quite possible to have 80 Unifact Pro controllers directly con-
nected on an NCP RS485 network; ARCNET and Satchnet networks
with routers can be much larger than this. With such large networks, to
achieve acceptable system performance, the number of signals
requested and their poll rate must be considered when engineering the
Xenta 555.
Note that Satchnet networks run four times slower than MicroNet NCP
networks.
12.2
Bandwidth and Performance
Because both MicroNet and Satchnet networks are polled, there is a lim-
ited bandwidth available in which to obtain all signal data. This means
that it is necessary for the Xenta 555 to request each programmed signal
(point) in turn from each controller. There are many factors which deter-
mine the performance of a network, however it is generally accepted
that certain signal parameters should update more frequently than oth-
ers. The Xenta 555 has a special dynamic poll scheme that is inherent in
the controller and needs no configuration. The polling of any signal
depends on the signal type and its poll frequency.
Priority is given to signals with the fastest poll rate, therefore some mea-
sure of control can be applied to the prioritization of signals. The most
important signals should be configured with the fastest poll rate.
In the event that a particular signal is referenced more than once, for
example, in an alarm, log and web page, that signal appears in the poll
scheme once only and is polled at the fastest rate (that is, the fastest of
the alarm rate, log rate or web page rate).
Typically, the order of engineering priority should be:
1
Alarms
2
Web pages
3
Logs.
Summary of Contents for Xenta 555
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Page 7: ...INTRODUCTION 1 About this Manual 2 About TAC Xenta 555...
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