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Rockwell Automation Publication 1789-UM002K-EN-P - January 2015
Chapter 7
Develop External Routines
Parameter Type Checking
Return Parameter
Only floating point and integer values can be returned from the external routine.
You cannot pass a pointer to a memory location as the return parameter. This is
enforced to maintain the integrity of the controller. Note that all memory that is
referenced by both the controller and an external routine must have been
allocated by the controller.
Logix Designer Application Data Type
Formal Parameter Enumeration
Allowed C Language Types (XML)
Literal integer value (such as 121)
IntegerValue
Char, short, int, long, bool
DINT
IntegerAddress
IntegerValue
VoidAddress
Int*, long*
Int, long
Void*
INT
IntegerAddress
IntegerValue
VoidAddress
Short*
Short
Void*
SINT
IntegerAddress
IntegerValue
VoidAddress
Char*
Char
Void*
Literal floating point values (such as 12.345)
FloatingPointValue
Float
REAL
FloatingPointAddress
FloatingPointValue
VoidAddress
Float*
Float
Void*
BOOL
IntegerAddress
IntegerValue
VoidAddress
Bool*
Bool
Void*
Literal BOOL
IntegerValue
Bool
UDT
StructureAddress
VoidAddress
Struct AnyStructT* s
Void*
Arrays
ArrayAddress
VoidAddress
Char var[], short var[], int var[], long var[], Bool var[],
float var[], struct AnyStructT var[]
Void*
Logix Designer Application Data Type
Formal Parameter Enumeration
Allowed C language Types (in XML)
DINT
IntegerValue
Int
Long
INT
IntegerValue
Short
SINT
IntegerValue
Char
REAL
FloatingPointValue
Float
BOOL
IntegerValue
Bool