377
Interrupt Functions
Section 8-1
a.
The following example shows duplicate processing by an interrupt
task, which interrupts processing of a +B instruction between the first
and third operands and overwrites the same memory address.
The interrupt occurs during processing of the +B instruction and the result is
saved temporarily without being written to the destination word (D0).
The interrupt task transfers the value of #0010 to D0, but the saved result of
the +B instruction (1235) is written to D0 when processing returns to the cyclic
task. In the end, the interrupt task’s processing has no effect.
Prevention of Duplicate Processing
+B
D0
#0001
D0
MOV
#0010
D0
D0
1234
0010
1235
Processing
interrupted.
Cyclic task
Interrupt task
Read D0 value (1234).
BCD addition: 1234 + 1 = 1235
Interrupt occurs.
MOV executed
0010 moved to D0.
Interrupt completed.
Data saved.
Addition result (1235)
Write addition result (1235).
Processing
of +B
instruction
Processing
continues.
Flow of Processing
+B
D0
#0001
D0
DI
EI
Cyclic task
Disables execution of
interrupt programs.
Enables execution of
interrupt programs.
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...
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