Omron CX-PROGRAMMER V9 Operation Manual page 156

OMRON
CX-Programmer allocates addresses within PLCs by trying to find space in the PLCs allocation areas (set as
above). The areas are searched in order, and addresses are only allocated within a particular range if its data type
is allowed within the range.
If automatic allocation is changed for a PLC (an allocation area is changed, or an area is removed), then all
automatically-allocated addresses for the PLC are reallocated.
If automatic allocation is removed for the PLC (i.e. the Enable automatic allocation for this PLC option is
removed), then any symbols that have been auto-allocated have their address removed.
Adding and Editing Automatic Allocation Areas
Selecting the Edit or Add button on the Automatic Allocation dialog opens the Memory Range dialog. This
dialog is used to either edit an existing auto allocation area or add a new one.
Enter the Start Address, the Size in channels (16 bit words) then select the Data types that can be allocated in
that area. On pressing the OK button, the address range is checked for validity and an appropriate error message
in a message box is displayed. On closing the message box the user is returned to this dialog and the first field
that is considered to be in error.
Note that it is not possible to select types until the restricted radio button has been selected otherwise the type
selection list box is grayed out. The type selection list box is a multiple selection list box.
Limitations
Timer/Counter memory areas are not available for address auto allocation.
It is not possible to have bit types in an area that is only word addressable.
The length of the address range must be less than or equal to the size of that memory area.
It is not possible to have auto allocation areas that overlap other areas.
The length of the address range must be greater than zero.
Copying Auto Allocated Symbols
When symbols are copied, any symbol with a fixed address is marked as being used if it occurs within an auto
allocated area. Auto allocated symbols that are copied across from one PLC to another will be assigned new
addresses within the auto allocation areas allowed on the PLC they are being transferred to. These symbols will
be assigned in alphabetical order rather than the order that they are copied across. If they have been assigned an
address by the PLC that they are being transferred from, they will not necessarily keep the same address.
Instructions
When contacts, coils, instructions and any symbols (auto allocated or not) are deleted, the address space they
occupied is freed for use by other elements as and when they are entered. Existing symbols that are auto
allocated but without an address are not updated and either needs to be re-entered or the auto allocation areas
need to be edited. Automatically allocated symbols are only allocated addresses when they are first entered or
when the auto allocation ranges are added/edited.
Rules for Auto Allocation
When the OK button is pressed and there are auto allocation areas to use, each of the programs is searched in
the order it appears in the tree. Each program is searched first for contacts, coils and instructions with fixed
addresses. If any of these fixed addresses are within an auto allocation area then those addresses are marked as
used and cannot be further auto allocated to other symbols. After this, non auto allocated symbols (symbols with
fixed addresses) within each program are checked. If any of these fixed symbols are within an auto allocation
area, then those symbol addresses are marked as used and cannot be further auto allocated to other symbols.
Finally, auto allocated symbols are allocated an address from the remaining addresses in an auto allocation area,
PART 1: CX-Programmer
CHAPTER 4 – Reference
CX-Programmer _Page 73