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

184 Timer and Counter InstructionsCTD Instruction Counter Control and Status Bits, Counter Word 0(Data File 5 is configured as a timer file for this example.)Bit Is Set When: And Remains Set Until One of the FollowingOccurs:bit 11 - C5:0/UNbit 13 - C5:0/DNbit 14 - C5:0/CDUN - underflowindicatorDN - doneindicatorCD - count downenablethe accumulated value wraps from-32,768…+32,767 and continues to countdownaccumulated value ≥ preset valuerung state is truea RES instruction with the same address as theCTD instruction is enabled• accumulated value < preset value or,• a RES instruction with the same address as theCTU instruction is enabled• rung state is false• a RES instruction with the same address as theCTD instruction is enabledPublication 1766-RM001A-EN-P - October 2008