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It is important to design the PLC program and SCADA application together. This will naturally help
create arrays of information, and optimise communications allowing CX-Server to collect data in the
most efficient manner.
Consider the examples in the following 2 figures:
In Figure (1) we see the PLC Programmer has arbitrarily chosen to group data by its format: Integers,
then BCD then Floats (or even worse not at all!). When the SCADA is written, this data is used by
different pages and different update rates. The different colours are to indicate that each block must
be read individually, totalling 9 communication requests, which could be for as few as 9 memory
addresses.
Release 2.0
PLC Memory
Integer
Integer
Integer
BCD
BCD
BCD
Float
Float
Float
Figure 1, Bad grouping example
CHAPTER 17 – Best Practices
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