CJ2 CPU Unit Software User's Manual - CIP ETI

6 I/O Memory Areas6-10 Holding AreaThe Holding Area addresses range from H000 to H511 for words and H000.00 to H511.15 for bits.These words can be used only in the program. Bits in this area will maintain the status when power isturned OFF or when the operating mode is changed from PROGRAM mode to RUN or MONITORmode or vice-versa.Holding Area bits can be used in any order in the program and can be used as normally open or normallyclosed conditions as often as necessary. Holding Area InitializationData in the Holding Area is not cleared when the PLC’s power supply is cycled or the CPU Unitoperating mode is changed from PROGRAM mode to RUN or MONITOR mode or vice-versa.A Holding Area bit will be cleared if it is programmed between IL(002) and ILC(003) and the executioncondition for IL(002) is OFF. To keep a bit ON even when the execution condition for IL(002) isOFF, turn ON the bit with the SET instruction just before IL(002). Self-maintaining BitsWhen a self-maintaining bit is programmed with a Holding Area bit, the self-maintaining bit won’t becleared even when the power is reset.H0.00H0.00If a Holding Area bit is not used for the self-maintaining bit, the bit will be turned OFF and the selfmaintainingbit will be cleared when the power is reset.If a Holding Area bit is used but not programmed as a self-maintaining bit as in the following diagram,the bit will be turned OFF by execution condition A when the power is reset.H0.00The Holding Area words from H512 to H1535 can be set for use with function blocks or SFC programs.Thesewords cannot be specified as instruction operands in the user program. PrecautionsWhen a Holding Area bit is used in a KEEP(011) instruction, never use a normally closed conditionfor the reset input if the input device uses an AC power supply. When the power supply goes OFF oris temporarily interrupted, the input will go OFF before the PLC’s internal power supply and the HoldingArea bit will be reset.Set inputInputUnitReset inputH0.006-20 CJ2 CPU Unit Software User’s Manual