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.
IEC Non-Standard Instructions
The red diamond symbol in front of an instruction located in the instruction tree denotes a non-standard IEC instruction.
Compiler Data Type Checking