Omron CX-PROGRAMMER V8.1, Operation Manual

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Function Block Specifications
Section 2-1
AT Settings (Allocation to Actual Addresses)
With internal variables, it is possible to set the variable to a particular I/O
memory address rather than having it allocated automatically by the system.
To specify a particular address, the user can input the desired I/O memory
address in this property. It is still necessary to use variable name in program-
ming even if a particular address is specified.
Note (1) The AT property can be set for internal variables only.
(2) AT settings can be used only with the CIO (Core I/O Area), A (Auxiliary
Area), D (Data Memory Area), E (Extended Memory Area, H (Holding
Relay Area), W (Internal Relay Area).
The AT property cannot be set in the following memory areas:
• Index Register and Data Register Areas (directly/indirectly specified)
• Indirectly specified DM/EM (: binary mode, *:BCD mode)
(3) AT settings can be used for the following allocations.
• Addresses for Basic I/O Units, CPU Bus Units, or Special I/O Units
• Auxiliary Area bits not registered as external variables in advance
• PLC addresses for other nodes in the network
Example:
If the READ DATA FILE instruction (FREAD) is being used in the function
block definition and it is necessary to check the File Memory Operation Flag
(A34313), use an internal variable and specify the flag’s address in the AT set-
ting.
Register an internal variable, select the AT setting option, and specify A34313
as the address. The status of the File Memory Operation Flag can be checked
through this internal variable.
When the AT setting is used, the function block loses its flexibility. This func-
tion should thus be used only when necessary.
Array Setting
With internal variables and input-output variables, a variable can be defined
as an array.
Note Only one-dimensional arrays are supported by the CX-Programmer.
With the array setting, a large number of variables with the same properties
can be used by registering just one variable.
• An array set for an internal variable can have from 1 to 32,000 array ele-
ments. An array set for an input-output variable can have the number of
elements given in the following table.
Address A34313 is allocated to a
boolean internal variable named
NOW_CARD_ACCESS.
Data type Number of elements
BOOL 2,048
INT/UINT/WORD 2,048