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The next page shows an example of the system design circuits, based on the
considerations described above.
DANGER
z
Install a safety circuit external to the PC that keeps the entire
system safe even when there are problems with the external
power supply or the PC module. Otherwise, trouble could
result from erroneous output or erroneous operation.
(1) Outside the PC, 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 PC detects the following problems, it will stop
calculation and turn off all output.
x
The power supply module has over current protection
equipment and over voltage protection equipment.
x
The PC CPUs self-diagnostic functions, such as the
watchdog timer error, detect problems. In addition, all
output will be turned on when there are problems that
the PC CPU cannot detect, such as in the I/O
controller. Build a fail safe circuit exterior to the PC that
will make sure the equipment operates safely at such
times. See Section 4.2 of this user's manual for
example fail safe circuits.
See this user's manual for example fail safe circuits.
(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.
z
Build a circuit that turns on the external power supply
when the PC main module power is turned on. If the
external power supply is turned on first, it could result in
erroneous output or erroneous operation.
Summary of Contents for Melsec A Series
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