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Procedures Section 3-2
3-2-6 Setting the FB Instance Areas
The areas where addresses for variables used in function blocks are allocated
can be set. These areas are called the function block instance areas.
1,2,3... 1. Select the instance in the Ladder Section Window or in the global symbol
table, and then select Function Block Memory - Function Block Memo-
ry Allocation from the PLC Menu.
The Function Block Memory Allocation Dialog shown below will appear.
2. Set the FB instance areas.
The non-retained and retained areas are set in words. The timer and
counter areas are set by time and counter numbers.
The default values are as follows:
Note (1) Bit data can be accessed even if the DM or EM Area is specified for the
non-retained area or retained area.
(2) The Function Block Holding Area words are allocated in H512 to H1535.
These words cannot be specified in instruction operands in the user pro-
gram. These words can also not be specified in the internal variable’s AT
settings.
(3) Words H512 to H1535 are contained in the Holding Area, but the ad-
dresses set as non-retained will be cleared when the power is turned
OFF and ON again or when operation is started.
(4) To prevent overlapping of instance area addresses and addresses used
in the program, set H512 to H1535 (Function Block Holding Area words)
for the non-retained area and retained area. If another area is set, the ad-
dresses may overlap with addresses that are used in the user program.
If the addresses in the function block instance areas overlap with any of
the addresses used in the user program, an error will occur when compil-
ing. This error will also occur when a program is downloaded, edited on-
line, or checked by the user.
FB Instance
Area
Default value Applicable memory
areas
Start Address End Address Size
Non Retain
(See notes 1
and 3.)
H512 (See
note 2.)
H1407 (See
note 2.)
896 CIO, WR, HR, DM, EM
Retain (See
note 1.)
H1408 (See
note 2.)
H1535 (See
note 2.)
128 HR, DM, EM
Timers T3072 T4095 1024 TIM
Counters C3072 C4095 1024 CNT
Non-retained area
Retained area
Counter area
Timer area
First
address
Last
address
Size
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