19.
19 -
1
LOADING AND INSTALLATION
19
LOADING AND INSTALLATION
This chapter describes the loading and installation procedures and precautions to obtain
the maximum system reliability and performance.
19.1 Fail-Safe Circuit Concept
When the PLC is powered ON or OFF, improper outputs may be generated temporarily
depending on the delay time and start-up time differences between the PLC power supply
and the external power supply for the control target (especially, DC).
For example, if the external power supply for a DC output module is powered ON and then
the PLC is powered ON, the DC output module may generate incorrect outputs temporarily
upon the PLC power-ON. To prevent this, it is required to build a circuit by which the PLC
is powered on first.
Also, an external power failure or PLC failure may lead to erroneous operation.
In order to eliminate the possibility of an system error and to ensure fail-safe operation,
create a circuit (emergency stop circuit, protection circuit, interlock circuit, etc.) outside the
PLC for the parts whose faulty operation could cause mechanical damage and/or
accidents.
A system design circuit example based on the above is provided later.
Summary of Contents for Q2ACPU
Page 1: ......
Page 2: ......
Page 221: ...12 12 12 OVERVIEW OF PROCESSING PERFORMED BY THE QnACPU ...
Page 222: ...12 13 12 OVERVIEW OF PROCESSING PERFORMED BY THE QnACPU ...
Page 237: ...12 28 12 OVERVIEW OF PROCESSING PERFORMED BY THE QnACPU MEMO ...
Page 271: ...16 13 16 POWER SUPPLY MODULE 4 Names and description of parts of the A66P ...
Page 343: ...21 21 13 MAINTENANCE AND INSPECTION 21 4 2 Replacement of the fuse for an output module ...
Page 357: ...22 12 22 TROUBLESHOOTING ...
Page 359: ...22 14 22 TROUBLESHOOTING MEMO ...
Page 429: ...App 32 APPENDICES Trigonometric function Classification Symbol Description ...
Page 537: ...App 140 APPENDICES REMARK 1 Message 1 An error code is displayed in 2 Alert 1 3 Alert 2 ...
Page 539: ...App 142 APPENDICES 2 Q2ACPU Q2ACPU S1 modules Unit mm inch ...
Page 541: ...App 144 APPENDICES 2 A66P power supply module Unit mm inch ...
Page 543: ...App 146 APPENDICES 3 A35B base unit 4 A38B A38HB A38HBEU base unit Unit mm inch Unit mm inch ...
Page 567: ...MEMO ...
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