60
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
Summary of Contents for CP1L-EL20DR-D
Page 3: ...CP1L EL20D CP1L EM30D CP1L EM40D CP1L EL EM CPU Unit Operation Manual Produced July 2017...
Page 4: ...iv...
Page 10: ...x...
Page 22: ...xxii...
Page 34: ...xxxiv Software Licenses and Copyrights 7...
Page 192: ...158 Trial Operation and Debugging Section 5 3...
Page 250: ...216 Automatic Clock Adjustment and Specifying Servers by Host Name Section 6 7...
Page 666: ...632 Trouble Shooting Section 11 7...
Page 696: ...662 Standard Models Appendix A...
Page 805: ...771 Connections to Serial Communications Option Boards Appendix F Connecting to Unit...
Page 806: ...772 Connections to Serial Communications Option Boards Appendix F...
Page 836: ...802 PLC Setup Appendix G...
Page 838: ...804 TCP Status Transitions Appendix H...
Page 840: ...806 Ethernet Network Parameters Appendix I...
Page 842: ...808 Buffer Configuration CP1L EL EM Appendix J...
Page 844: ...810 Ethernet Specifications Appendix K...
Page 851: ...Index 817 work words 118 write protection 447...
Page 852: ...818 Index...
Page 854: ...820 Revision History...
Page 855: ......