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CHAPTER3 CPU MODULE OPERATION
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3.2 I/O Refresh (Refresh Processing with Input/Output Modules)
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3.2 I/O Refresh (Refresh Processing with Input/Output Modules)
The CPU module performs the following before sequence program operations.
• On/off data input from the input module or intelligent function module to the CPU module
• On/off data output from the CPU module to the output module or intelligent function module
When the constant scan time is set, I/O refresh is performed after the constant scan waiting time has
elapsed.
(I/O refresh is performed at each constant scan cycle.)
3.3 Program Operation
The CPU module sequentially executes the program stored in the module from the step 0 to the END or
FEND instruction.( CHAPTER 2)
3.4 END Processing
The CPU module performs refresh processing with network modules and communication with external
devices.
END processing includes the following.
• Refresh with network modules ( CHAPTER 10)
• Auto refresh with intelligent function module ( Section 7.1.1)
• Intelligent function module dedicated instruction processing ( CHAPTER 10)
• Device data latch processing ( Section 6.3, CHAPTER 10)
• Service processing ( Section 6.24, CHAPTER 10)
• Watchdog timer reset ( Section 6.16)
• Auto refresh between multiple CPU modules ( QCPU User's Manual (Multiple CPU System))
• Device data collection using the sampling trace function (only when trace point is set to every scan (after
END instruction execution)) ( Section 6.14)
• Self-diagnostics processing ( Section 6.17)
• Special relay/special register value setting (only for those that should be set during END processing)
( CHAPTER 12)
When the constant scan function ( Section 6.2) is used, the results of processing performed in
END processing are held for the period between after END processing is completed and until the
next scan starts.