378
Interrupt Functions
Section 8-1
b.
The following example shows duplicate processing by an interrupt
task, which interrupts processing while BSET is writing to a block of
words and yields an incorrect comparison result.
Since the interrupt occurs during BSET(071) processing and before #1234 is
set in D10, the content of D0 and D10 do not match when the comparison is
made in the interrupt task (*1) and output A remains OFF.
In the end (*2), the D0 and D10 both contain #1234 and match, but the correct
comparison result is not reflected in comparison result output A.
Prevention of Duplicate Processing
BSET
#1234
D0
D10
CMP
D0
D10
A
1234
1234
1234
0502
ABCD
ABCD
ABCD
1234
OFF
OFF*
1
003E 0502
D0
D1
D2
D10
A
1234*
2
OFF
Cyclic task
Interrupt task
Equals Flag
#1234 set in D0.
#1234 set in D1.
#1234 set in D2.
#1234 set in D10.
BSET(071)
processing
CMP(020)
processing
Read D0.
Read D1.
Output result.
Compare D0 and D10.
Interrupted.
Continued.
Interrupt occurs.
Interrupt completed.
1234
1234
1234
Flow of Processing
BSET
#1234
D0
D10
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...
Page 855: ......