Utilizing IEC Overloaded and Non-Standard Instructions

IEC Overloaded Instructions

The key points essential to programming in IEC mode and using overloaded instructions are listed below.

·The input parameters of overloaded instructions must be consistent in size with the output parameters: for instance, if your inputs are word values, your outputs must be word values-- they cannot be byte values or double-word values.

·Any variable operands of an overloaded instruction must have the same data type as the other parameters of that instruction.

·At least one operand must be a variable and have a data type assigned.

The following IEC instructions are overloaded.

ADDANDSHLLT

SUBORSHRGT

MULXORROLLE

DIVNOTRORGE

INCMOVEEQ

DECBLKMOVENE

IEC Non-Standard Instructions

The red diamond symbol in front of an instruction located in the instruction tree denotes a non-standard IEC instruction.

See Also:

Compiler Data Type Checking