Omron CJ1W-ETN21 operation manual Safety Precautions

Safety Precautions 3

!WARNING Provide safety measures in external circuits (i.e., not in the Programmable Controller), including the following items, to ensure safety in the system if an abnormality occurs due to malfunction of the PLC or another external factor affecting the PLC operation. Not doing so may result in serious accidents.

•Emergency stop circuits, interlock circuits, limit circuits, and similar safety measures must be provided in external control circuits.

•The PLC will turn OFF all outputs when its self-diagnosis function detects any error or when a severe failure alarm (FALS) instruction is executed. As a countermeasure for such errors, external safety measures must be provided to ensure safety in the system.

•The PLC outputs may remain ON or OFF due to deposits on or burning of the output relays, or destruction of the output transistors. As a counter- measure for such problems, external safety measures must be provided to ensure safety in the system.

•When the 24-V DC output (service power supply to the PLC) is over- loaded or short-circuited, the voltage may drop and result in the outputs being turned OFF. As a countermeasure for such problems, external safety measures must be provided to ensure safety in the system.

!Caution Execute online editing only after confirming that no adverse effects will be caused by extending the cycle time. Otherwise, the input signals may not be readable.

•Emergency stop circuits, interlock circuits, limit circuits, and similar safety measures must be provided in external control circuits.

!Caution Fail-safe measures must be taken by the customer to ensure safety in the event of incorrect, missing, or abnormal signals caused by broken signal lines, momentary power interruptions, or other causes. Serious accidents may result from abnormal operation if proper measures are not provided.

!Caution Confirm safety at the destination node before changing or transferring to another node the contents of a program, the PLC Setup, I/O tables, or I/O memory. Changing or transferring any of these without confirming safety may result in injury.

!Caution Tighten the screws on the terminal block of the AC Power Supply Unit to the torque specified in the operation manual. The loose screws may result in burning or malfunction.

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