Assigning Variables to LL984 Objects
Original instructions
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Introduction
In the LL984 Editor you can assign a variable (like _400001 or sym1) or an address (like %M1) to an FFB pin or to a contact/coil.
If the variable is not declared, the Create variable? dialog opens.
If the variable or address assigned is not compatible with the pin or contact/coil, a message will be displayed in the output window after Build → Analyze.
Automatic Variable Naming
If you, for example, assign an address (e.g. %MW1) to a pin, the Create variable? dialog opens proposing a variable name (e.g. _400001) and a data type (e.g. UINT).
The following rules apply to this automatic proposal, depending on the address of the actual parameter, the pin type and dimension (n) in case of an array type:
Address
Pin Type
Dimension (for array types)
Variable Name
%MW1
UINT
1 (n)
_400001 (_400001_n)
INT
_400001_I (_400001_In)
WORD
_400001_W (_400001_Wn)
%IW1
UINT
1 (n)
_300001 (_300001_n)
INT
_300001_I (_300001_In)
WORD
_300001_W (_300001_Wn)
%I1
EBOOL
1 (n)
_100001 (_100001_n)
%M1
EBOOL
1 (n)
_000001 (_000001_n)
NOTE: For the most used pin types UINT and EBOOL no type suffix are appended to the proposed variable name.
Use Case 1
Assignment to a pin of type UINT
User-Assigned Address
Variable
Variable Created and Assigned
Variable Type
%MW1
not existing yet
_400001
UINT
NOTE: As the pin type was UINT no type suffix was appended to the variable name.
Use Case 2
Assignment to a pin of type ARRAY[1...n] of UINT
User-Assigned Address
Variable
Variable Created and Assigned
Variable Type
%MW1
not existing yet
_400001_n
ARRAY[1...n] of UINT
Use Case 3
Assignment to a pin of type ANY or ANY_ARRAY_UINT or ANY_ARRAY_BOOL (dynamic array)
The dimension (n) of a dynamic array will be provided by another dimension pin (e.g. LENGTH) of the function block.
This dimension pin will be initialized during block insertion.
The dimension of the array will be calculated based on the dimension pin value entered as actual parameter of the dimension pin.
User-Assigned Address
Variable
Variable Created and Assigned
Variable Type
%MW1
not existing yet
_400001_n
ARRAY[1...n] of UINT
If you modify n on the dimension pin to n2:
User-Assigned Address
Variable
Variable Created and Assigned
Variable Type
%MW1
not existing yet
_400001_n2
ARRAY[1...n2] of UINT
%MW1
already existing
_400001_n2
attributes (like descriptors, comments etc.) are taken over
ARRAY[1...n2] of UINT
Use Case 4
Assignment to a pin of type DDT1
User-Assigned Address
Variable
Variable Created and Assigned
Variable Type
%MW1
not existing yet
_400001_DDT1
DDT1
Memory Consumption
If you create any kind of located variables (elementary type, array or DDT) this will not increase memory consumption on the PLC (except for Upload information).
New Variable Creation
If you assign a different address or modify a dimension pin, a new variable will be created.
The old attributes (except the address) will be overtaken and the old variable will be deleted, if it is not used anywhere else in the program.
Invalid Variables
If you create a located variable with an address range which exceeds the address range defined under State RAM of the CPU´s Configuration tab, the following message will be displayed after Build → Analyze:
Topological address index is not valid.
There are different ways to solve this issue:
NOTE: If you just create a new variable at the pin of the function block without deleting the previously created, invalid variable the message mentioned above will be displayed again after next Build → Analyze.
Example:
Under State RAM of the CPU´s Configuration tab you entered a value 10000 for %MW.
In your program you have an L_BLKM function block with LENGTH = 10.
At the SOURCE pin of the function block you enter following value: %MW9999.
This results in creation of the following variable:
_409999:ARRAY[1..10] OF UINT@%MW9999
As the start address is %MW9999 and the length is 10, the end address will be %MW10009.
This exceeds the address range (10000) defined under State RAM of the CPU´s Configuration tab.
Therefore the message mentioned above will be displayed after Build → Analyze.