Logix5000 Controllers General Instructions - SLAC Confluence

636 Common AttributesInstructions execute faster and require less memory if all the operandsof the instruction use:• the same data type• an optimal data type:– In the “Operands” section of each instruction in this manual, abold data type indicates an optimal data type.– The DINT and REAL data types are typically the optimaldata types.– Most function block instruction only support one data type(the optimal data type) for its operands.If you mix data types and use tags that are not the optimal data type,the controller converts the data according to these rules• Are any of the operands a REAL value?IfYesNoThen input operands (for example., source, tag in an expression,limit) convert toREALsDINTs• After instruction execution, the result (a DINT or REAL value)converts to the destination data type, if necessary.You cannot specify a BOOL tag in an instruction that operates oninteger or REAL data types.Because the conversion of data takes additional time and memory,you can increase the efficiency of your programs by:• using the same data type throughout the instruction• minimizing the use of the SINT or INT data typesIn other words, use all DINT tags or all REAL tags, along withimmediate values, in your instructions.The following sections explain how the data is converted when youuse SINT or INT tags or when you mix data types.Publication 1756-RM003I-EN-P - January 2007