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Memory structure
(
continued)
Presentation:
page 1/4
Description:
pages 1/5 …
References:
pages 1/10 …
PCMCIA references:
pages 1/12 …
Memory structure
(
continued)
Extension of the data storage area
Memory cards reserved for data storage (4096 or 8192 Kb) are used to:
b
Access the data storage area when the application is fully loaded into the internal
RAM. In this case, the data storage memory card is inserted into PCMCIA slot no. 0.
b
Free up memory to serve as additional program space when the application is on
the PCMCIA card (slot no. 0). In this case, the data storage memory card is inserted
into PCMCIA slot no. 1 (although the memory card in slot no. 0 can still be used for
some of the data).
Unity Pro programming software helps the application designer to manage the
structure and organize how the memory space on the Premium PLC is occupied.
Protecting the application
Regardless of the PLC memory structure (whether the application is located in the
internal RAM or on the PCMCIA card), it is possible to prevent the application from
being accessed (for reading or modifying the program) by only loading the
executable code into the PLC.
Amemory protection bit, set in configuration mode, is also available to prevent any
program modification (via the programming terminal or downloads).
Program modification in online mode
This function is different from previous versions of Premium PLCs (with PL7
software) in that it now allows program code and data from different parts of the
application to be added or modified in a single modification session (thus making
modification unified and consistent with regard to the controlled process).
This increased flexibility comes at a cost in terms of the amount of program memory
required. In order for the program to be modified in online mode, the amount of
program memory space available must be at least equal to the combined size of all
sections of the Unity Pro program affected by the single modification session
concerned.
Depending on circumstances:
b
In the case of a processor with a memory extension card, there will be sufficient
memory left on the card for online modification, provided that the recommendations
on page 1/12 are observed.
b
In the case of a processor without a memory extension card, if the user wants to
be able to make modifications in online mode, he or she must select a processor on
the basis of the following:
v
The anticipated size of the application
v
The number and size of the program sections to be modified in online mode
Note
:
Amemory extension card based exclusively on Flash EPROM technology (without
additional SRAM) is clearly incapable of supporting program modifications in online mode.
(1)
As from
TSX P57 20
processors.
Modicon Premium automation
platform
0
Unity processors
1
1
2
3
4
4
Internal RAM
PCMCIA card
(
slot no. 0)
Located data
96
to 2048 Kb
Processor with mixed type memory card in slot no. 0 and data
storage type memory card in slot no. 1 (1)
Program and
symbols
Constants
Additional data
storage (area A)
Additional data
storage (area B)
Global unlocated data
and DFBs
Data storage
PCMCIA card
(
slot no. 1)
128
to 7168 KB
4096
or 8192 KB
2
1
3
4
5
6
7
8
9
10