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MELSEC-Q
9 LOADING AND INSTALLATION
9 LOADING AND INSTALLATION
In order to increase the reliability of the system and exploit the maximum performance
of its functions, this section describes the methods and precautions for the mounting
and installation of the system.
9.1 General Safety Requirements
!
DANGER
Install a safety circuit external to the PLC that keeps the entire
system safe even when there are problems with the external power
supply or the PLC module. Otherwise, trouble could result from
erroneous output or erroneous operation.
(1) Outside the PLC, construct mechanical damage preventing
interlock circuits such as emergency stop, protective circuits,
positioning upper and lower limits switches and interlocking
forward/reverse operations.
(2) When the PLC detects the following problems, it will stop
calculation and turn off all output in the case of (a).
In the case of (b), it will stop calculation and hold or turn off all
output according to the parameter setting.
Note that the A1S series module will turn off the output in either
of cases (a) and (b).
All outputs of AnS Series Module will be switched off in the
following cases:
(a) The power supply module has over current protection
equipment and over voltage protection equipment.
(b) The PLC CPUs self-diagnosis functions, such as the watch
dog timer error, detect problems.
In addition, all output will be turned on when there are problems
that the PLC CPU cannot detect, such as in the I/O controller.
(3) Output could be left on or off when there is trouble in the outputs
module relay or transistor. So build an external monitoring circuit
that will monitor any single outputs that could cause serious
trouble.
When overcurrent which exceeds the rating or caused by short-
circuited load flows in the output module for a long time, it may
cause smoke or fire. To prevent this, configure an external safety
circuit, such as fuse.
Build a circuit that turns on the external power supply when the PLC
main module power is turned on. If the external power supply is
turned on first, it could result in erroneous output or erroneous
operation.
When there are communication problems with the data link, refer to
the corresponding data link manual for the operating status of each
station. Not doing so could result in erroneous output or erroneous
operation.operating status of each station. Not doing so could result
in erroneous output or erroneous operation.
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