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77
Computing the Cycle Time
Section 2-7
2-7
Computing the Cycle Time
2-7-1
CPU Unit Operation Flowchart
The CPU Unit processes data in repeating cycles from the overseeing pro-
cessing up to peripheral servicing as shown in the following diagram.
NO
YES
Power ON
Checks Unit connection status.
Checks hardware and user
program memory.
Executes user program (i.e.,
executes READY cyclic tasks).
Waits until the set cycle time
has elapsed.
Calculates cycle time.
Sets error flags.
Performs I/O refreshing.
Services peripheral devices.
Peripheral
servicing
I/O
refreshing
Cycle time
calculation
Program
execution
Overseeing
processing
PLC
cycle
time
Startup
initialization
Check OK?
ERR/ALM
indicator ON or
flashing?
End of program?
Flashing
(nonfatal error)
ON (fatal error)
Error
Normal
Содержание CP1L - 12-2007
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Страница 13: ...xiv TABLE OF CONTENTS...
Страница 21: ...xxii...
Страница 33: ...xxxiv Conformance to EC Directives 6...
Страница 65: ...32 Function Blocks Section 1 5...
Страница 428: ...395 Clock Section 6 9...
Страница 429: ...396 Clock Section 6 9...
Страница 523: ...488 Troubleshooting Unit Errors Section 9 4...
Страница 531: ...496 Replacing User serviceable Parts Section 10 2...
Страница 563: ...528 Auxiliary Area Allocations by Function Appendix C...
Страница 611: ...576 Auxiliary Area Allocations by Address Appendix D...
Страница 638: ...603 Connections to Serial Communications Option Boards Appendix F Connecting to Unit...
Страница 639: ...604 Connections to Serial Communications Option Boards Appendix F...
Страница 669: ...634 Index...
Страница 671: ...636 Revision History...