12 -
8
12. OVERVIEW OF PROCESSING PERFORMED BY THE QnACPU
(5) Scan time
• The scan time is a total of the scan execution type program execution time, the
END processing time, and either the low-speed program execution time or the
constant scan waiting time.
*1
When more than one scan execution type program is executed, "the execution
time of the scan execution type program" is the time required for completing
execution of all these programs.
*1
Refer to Section 12.1.3.
• The QnACPU measures the present, minimum, and maximum values for the scan
time and stores them in special registers SD520, SD521, and SD524 to SD527.
*2
The scan time can be checked by monitoring these special registers.
*2
The accuracy of each scan time stored in the special registers is 0.1ms. Note that, even if
the watchdog timer (WDT) reset instruction is executed in the sequence program,
measurement of each scan time is continued.
(6) WDT (watchdog timer)
This is a timer that monitors the scan time; and 200ms is set as a default value.
WDT is set within the range of 10ms to 2000ms in "PLC RAS" in the parameter
mode. (Unit: 10ms).
When using a low-speed execution type program(s), make sure that the specified
WDT value is greater than the sum of the scan time and the low-speed execution
type program execution time.
If the scan time (total of execution times for scan execution type programs and low-
speed execution type programs, END processing time, and low-speed END
processing time) exceeds the time set for WDT, a "WDT ERROR" occurs and the
QnACPU stops its operation.
Example:If "3" and "400" are stored in SD520 and SD521 respectively, the scan
time is 3.4ms.
POINT
The WDT measurement error is 0 to 10ms.
Because of this, when WDT (t) is set to 10ms, a WDT ERROR may not occur
even if the scan time exceeds the limit within the range of 10ms t 20ms.
Содержание Q2ACPU
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Страница 269: ...16 11 16 POWER SUPPLY MODULE 2 Names and description of parts of the A62P A62PEU and A65P module ...
Страница 271: ...16 13 16 POWER SUPPLY MODULE 4 Names and description of parts of the A66P ...
Страница 343: ...21 21 13 MAINTENANCE AND INSPECTION 21 4 2 Replacement of the fuse for an output module ...
Страница 357: ...22 12 22 TROUBLESHOOTING ...
Страница 359: ...22 14 22 TROUBLESHOOTING MEMO ...
Страница 417: ...App 20 APPENDICES 3 Shift instructions Classification Symbol Description n bit shift 1 bit shift 1 word shift ...
Страница 429: ...App 32 APPENDICES Trigonometric function Classification Symbol Description ...
Страница 432: ...App 35 APPENDICES 15 Clock instructions Classification Symbol Description Clock data read write ...
Страница 537: ...App 140 APPENDICES REMARK 1 Message 1 An error code is displayed in 2 Alert 1 3 Alert 2 ...
Страница 538: ...App 141 APPENDICES APPENDIX 6 EXTERNAL DIMENSIONS Appendix 6 1 CPU Module 1 Q3ACPU Q4ACPU modules Unit mm inch ...
Страница 539: ...App 142 APPENDICES 2 Q2ACPU Q2ACPU S1 modules Unit mm inch ...
Страница 541: ...App 144 APPENDICES 2 A66P power supply module Unit mm inch ...
Страница 542: ...App 145 APPENDICES Appendix 6 3 Main Base Unit 1 A32B base unit 2 A32B S1 base unit Unit mm inch Unit mm inch ...
Страница 543: ...App 146 APPENDICES 3 A35B base unit 4 A38B A38HB A38HBEU base unit Unit mm inch Unit mm inch ...
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