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CPU Unit Operating Modes Section 2-5
2-5 CPU Unit Operating Modes
2-5-1 Operating Modes
The CPU Unit has three operating modes that control the entire user program
and are common to all tasks.
PROGRAM: Programs are not executed and preparations, such as initial-
izing the PLC Setup and other settings, transferring pro-
grams, checking programs, force-setting and force-resetting
can be executed prior to program execution.
MONITOR: Programs are executed, but some operations, such as online
editing, forced-set/reset, and changes to present values in I/O
memory, are enabled for trial operation and other adjust-
ments.
RUN: Programs are executed and some operations are disabled.
2-5-2 Status and Operations in Each Operating Mode
The following table lists status and operations for each mode.
Note The following table shows the relationship of operating modes to tasks.
Operation PROGRAM mode RUN mode MONITOR mode
Program execution Stopped Executed Executed
I/O refreshing Executed Executed Executed
External I/O status OFF According to program According to program
I/O memory Non-holding memory Cleared According to program According to program
Holding memory Held
CX-Programmer
operations
I/O memory monitoring OK OK OK
Program monitoring OK OK OK
Program
transfers
From CPU Unit OK OK OK
To CPU Unit OK XX
Checking program OK XX
Setting PLC Setup OK XX
Changing program OK X OK
Force-setting/resetting OK X OK
Changing timer/counter SV OK X OK
Changing timer/counter PV OK X OK
Change I/O memory PV OK X OK
Mode Cyclic task status Interrupt task
status
PROGRAM Disabled status (INI) Stopped
RUN • Any task that has not yet been executed, will be in disabled status (INI).
• A task will go to READY status if the task is set to go to READY status at star-
tup or the TASK ON (TKON) instruction has been executed for it.
• A task in READY status will be executed (RUN status) when it obtains the
right to execute.
• A status will go to Standby status (WAIT) if a READY task is put into Standby
status by a TASK OFF (TKOF) instruction.
Executed if inter-
rupt condition is
met.
MONITOR
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