Logix5000 Controllers General Instructions - SLAC Confluence

388 Array (File)/Shift Instructions (BSL, BSR, FFL, FFU, LFL, LFU)Bit Shift Left (BSL)The BSL instruction shifts the specified bits within the Array oneposition left.Operands:Relay LadderOperand Type Format DescriptionArray DINT array tag array to modifyCONTROL Structurespecify the first element of the group ofelementsdo not use CONTROL.POS in the subscriptControl CONTROL tag control structure for the operationSource bit BOOL tag bit to shiftLength DINT immediate number of bits in the array to shiftMnemonic Data Type Description.EN BOOL The enable bit indicates that the BSL instruction is enabled..DN BOOL The done bit is set to indicate that bits shifted one position to the left..UL BOOL The unload bit is the instruction’s output. The .UL bit stores the status of the bit that wasshifted out of the range of bits..ER BOOL The error bit is set when .LEN < 0..LEN DINT The length specifies the number of array bits to shift.Description:When enabled, the instruction unloads the uppermost bit of thespecified bits to the .UL bit, shifts the remaining bits one position left,and loads Source bit into bit 0 of Array.IMPORTANTYou must test and confirm that the instruction doesn’t change data that you don’twant it to change.The BSL instruction operates on contiguous memory. In some cases, the instructionshifts bits past the array into other members of the tag. This happens if the length istoo big and the tag is a user-defined data type.Arithmetic Status Flags:Fault Conditions:not affectednonePublication 1756-RM003I-EN-P - January 2007