1766-RM001A-EN-P MicroLogix 1400 Programmable Controllers ...

222 Math InstructionsUse the ATN instruction to take the arc tangent of a number (source) andstore the result (in radians) in the destination. The resulting value in thedestination is always greater than or equal to -π/2 and less than or equalto π/2, where π = 3.141592.Enter the following parameters when programming this instruction:• Source is the address to compute the arc tangent.• Destination is the address to store the arc tangent of the Source.Address Levels for the operands involved in the ATN can be ALL word,ALL double word, ALL float, or a combination. These operands shallundergo a conversion to float. The calculation of the source (in float) isthen performed, and the result is then cast to the data type of Destination.ATN Instruction Valid Addressing Modes and File TypesFor definitions of the terms used in this table see Using the Instruction Descriptions on page 92.Data Files Function Files (1)Address Mode (3)Address LevelParameterOISBT, C, RNFSTLMG, PDRI/RIXPLSRTCHSCPTOX, PWMXSTIEIIBHIMMILCDCS - CommsIOS - I/ODLS - Data Log (2)DirectIndirectImmediateInt16Immediate Int32Immediate FloatBitWordDouble WordElementFloatSource • • • • • • • • • • • • • • • • •Destination • • • • • • • • • • • • •(1) PTOX and PWMX files are only for use with MicroLogix 1400 BXB or BXBA unit.(2) The Data Log Status file can only be used for the following math instructions: ADD, SUB, MUL, DIV, NEG, and SCP.(3) See Important note about indirect addressing.IMPORTANTYou cannot use indirect addressing with: S, MG, PD, RTC, HSC, PTOX,PWMX, STI, EII, BHI, MMI, CS, IOS, and DLS files.Instruction OperationWhen the rung is true, this instruction shall compute arc tangent of theSource and place the result in Destination. Valid input range is from-∝…+∝ and produced output range is from -π/2…π/2.If the Destination is floating point, the result shall always be roundedusing the round to even rule.Publication 1766-RM001A-EN-P - October 2008