Logix5000 Controllers General Instructions - SLAC Confluence

402 Array (File)/Shift Instructions (BSL, BSR, FFL, FFU, LFL, LFU)FIFO Unload (FFU)The FFU instruction unloads the value from position 0 (first position)of the FIFO and stores that value in the Destination. The remainingdata in the FIFO shifts down one position.Operands:Relay LadderOperand Type Format DescriptionFIFO SINT array tag FIFO to modifyINTDINTspecify the first element of the FIFOdo not use CONTROL.POS in the subscriptREALstringstructureDestinationSINTtagvalue that exits the FIFOINTDINTREALstringstructureThe Destination value converts to the data type of the Destination tag. Asmaller integer converts to a larger integer by sign-extension.Control CONTROL tag control structure for the operationtypically use the same CONTROL as theassociated FFLLength DINT immediate maximum number of elements the FIFO canhold at one timePosition DINT immediate next location in the FIFO where theinstruction unloads datainitial value is typically 0If you use a user-defined structure as the data type for the FIFO orDestination operand, use the same structure for both operands.Publication 1756-RM003I-EN-P - January 2007