Omron CX-SUPERVISOR - V2.0, User Manual

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OMRON CHAPTER 17 – Best Practices
Release 2.0 Page 257
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Use Fins event memory
If your communications is using a Fins driver (e.g. Controller Link) it is possible to create a
responsive application giving the impression of high performance by linking the SCADA to the event
memory, which the network updates automatically. Of course reads and writes actually access the
local cache very quickly although this will lag behind actual device values.
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Control communications
Use the 'On Request' update type to give you complete control over when the value of a point is read
from the PLC or written to the PLC. The 'InputPoint' script function is used to input the value of a
specified point and the 'OutputPoint' script function is used to output the value of a specified point.
Points
This section covers some good practices with the Points for quicker development and smoother
running.
• Define as few points as possible.
Keep the Points database as slim and manageable as possible by:
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Using arrays where possible especially for PLC points
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If memory points are defined for scripting try to reuse general purpose points like
‘nLoopCounter’, ‘bReturnValue’, ‘nTemp’
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Use expressions in animations instead of calculating new values e.g. using “Temper
273” rather than creating a new “TemperatureCelsius” memory point.
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For memory areas that are bit and word addressable, access as words. If you want the bits
use expressions with & and | operators e.g. Display Digital animation expression ‘MyW100
& 0x80’ and ‘MyW100 & 0x40’ instead of ‘MyW100bit8’ etc.
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Reduce the number of active points
Aim to reduce the number of active points, that are currently communicating where possible:
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Automatically by setting “Update when on Display” option
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Manually using script (EnablePoint(), DisablePoint(), OpenPLC(), ClosePLC() etc).
• Have a minimum of Input/Output points
Double-check the use of all Input/Output points. Don’t forget that ‘Output’ points can actually have
‘Data Transfer’ set to input the value only once on start up.