Logix5000 Controllers General Instructions - SLAC Confluence

378 Array (File)/Misc. Instructions (FAL, FSC, COP, CPS, FLL, AVE, SRT, STD, SIZE)File Standard Deviation(STD)The STD instruction calculates the standard deviation of a set of valuesin one dimension of the Array and stores the result in the Destination.Operands:Relay LadderOperand Type Format DescriptionArray SINTINTDINTREALarray tag find the standard deviation of the values inthis arrayspecify the first element of the group ofelements to use in calculating the standarddeviationdo not use CONTROL.POS in the subscriptA SINT or INT tag converts to a DINT value by sign-extension.Dimensionto varyDINTimmediate(0, 1, 2)which dimension to usedepending on the number of dimensions, theorder isarray[dim_0,dim_1,dim_2]array[dim_0,dim_1]array[dim_0]Destination REAL tag result of the operationControl CONTROL tag control structure for the operationLength DINT immediate number of elements of the array to use incalculating the standard deviationPosition DINT immediate current element in the arrayinitial value is typically 0CONTROL StructureMnemonic Data Type Description.EN BOOL The enable bit indicates that the STD instruction is enabled..DN BOOL The done bit is set when the calculation is complete..ER BOOL The error bit is set when the instruction generates an overflow. The instruction stopsexecuting until the program clears the .ER bit. The position of the element that caused theoverflow is stored in the .POS value..LEN DINT The length specifies the number of elements in the array on which the instruction operates..POS DINT The position contains the position of the current element that the instruction is accessing.Publication 1756-RM003I-EN-P - January 2007