Please install a protection circuit on the exterior of PLC so that the
whole system may operate safely regardless of failures from
external power or PLC. Any abnormal output or operation from PLC may cause serious problems
to safety in whole system.
- Install protection units on the exterior of PLC like an interlock circuit that deals with opposite
operations such as emergency stop, protection circuit, and forward/reverse rotation or install an
interlock circuit that deals with high/low limit under its position controls.
- If any system error (watch-dog timer error, module installation error, etc.) is detected during
CPU operation in PLC, all output signals are designed to be turned off and stopped for safety.
However, there are cases when output signals remain active due to device failures in Relay and
TR which can’t be detected. Thus, you are recommended to install an addition circuit to monitor
the output status for those critical outputs which may cause significant problems.
Never overload more than rated current of output module nor
allow to have a short circuit. Over current for a long period time may
cause a fire .
Never let the external power of the output circuit to be on earlier
than PLC power, which may cause accidents from abnormal output or
operation.
Please install interlock circuits in the sequence program for safe operations in the system
when exchange data with PLC or modify operation modes using a computer or other
external equipments Read specific instructions thoroughly when conducting control operations
with PLC.
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