CJ2 CPU Unit Software User's Manual - CIP ETI

6 I/O Memory Areas6-1 I/O Memory Areas6-1-1 I/O Memory Area OverviewI/O memory areas can be accessed using instruction operands. The following table lists the areas in I/OMemory.Area name Description ReferenceCIO Area (Core I/O Area) Words in the CIO Area are used for data exchanges such as I/O refreshing withvarious Units. Words that are not allocated to Units may be used as work wordsand work bits in the program. It is not necessary to input the “CIO” prefix whenspecifying an address in the CIO Area.---I/O Area Words in the I/O Area are allocated to external I/O terminals on Basic I/O Units. 6-8Data Link AreaWords in the Data Link Area are used for data links with other PLC Units on a 6-13network through a Controller Link Unit.Synchronous DataRefresh AreaCPU Bus Unit AreaSpecial I/O Unit AreaSerial PLC Link AreaWords in the Synchronous Data Refresh Area are allocated as synchronousrefresh data when synchronous unit operation is used.Words in the CPU Bus Unit Area are allocated to CPU Bus Units to transfer statusinformation.Words in the Special I/O Unit Area are allocated to Special I/O Units to transferstatus information.This area is used for Serial PLC Links. Data is exchanged between CPU Unitsusing serial ports without communications programming. This area is supportedonly by CJ2M CPU Units.DeviceNet AreaWords in the DeviceNet Area are allocated to slaves for DeviceNet remote I/O 6-18communications. Allocations in this area are fixed and cannot be changed.Internal I/O Area *1 These words can be used only in the program. They cannot be used for I/O ---exchange with external I/O terminals.Work Area (W) *1 Words in the Work Area can be used only in the program. 6-19Holding Area (H)Words in the Holding Area can be used only in the program. These words retaintheir content when the PLC is turned ON or the operating mode is switchedbetween PROGRAM mode and RUN or MONITOR mode.6-20Auxiliary Area (A)Temporary Relay Area(TR) (TR Area)Data Memory Area (D)(DM Area)Extended Data MemoryArea (E)(EM Area)TimerAreasTimer CompletionFlag Area(T)Timer PV Area(T)The Auxiliary Area contains flags and control bits used to monitor and controlPLC operation.The TR Area contains bits that record the ON/OFF status of program branches.The TR bits are used with mnemonics only.The DM Area is a multi-purpose data area. With CJ2 PLCs, the DM Area can beread and written in either word units or bit units.Words in the DM Area retain their contents when the PLC is turned ON or theoperating mode is switched between PROGRAM mode and RUN or MONITORmode.Some words in the DM Area are used to store initial settings for Special I/OUnits and CPU Bus Units.The EM Area is a multi-purpose data area. With CJ2 PLCs, the EM Area can beread and written in either word units or bit units.Words in the EM Area retain their content when the PLC is turned ON or theoperating mode is switched between PROGRAM mode and RUN or MONITORmode. The EM Area is divided into banks.6-146-156-166-176-226-236-246-27A Completion Flag is turned ON when the set time of the timer elapses. 6-31The PV of a timer increases or decreases as the timer operates.6-2 CJ2 CPU Unit Software User’s Manual