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Safety Instruction
Safety Instructions
for design process
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 maycause 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 oroperation.
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.
Warning