Fail-Safe Circuits - Omron CJ1W-ID Series User Manual

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Fail-safe Circuits

Provide safety measures in external circuits, including the following items, to
ensure safety in the system if an abnormality occurs due to malfunction of the
CPU Unit, other Units, or slaves or due to other external factors affecting opera-
tion. Not doing so may result in serious accidents due to incorrect operation.
• Emergency stop circuits, interlock circuits, limit circuits, and similar safety mea-
sures must be provided in external control circuits.
• The Controller outputs may remain ON or OFF due to deposition or burning of
the output relays or destruction of the output transistors. As a countermeasure
for such problems, external safety measures must be provided to ensure safe
operation of the system.
• The CPU Unit will turn OFF all outputs from Basic Output Units in the following
cases. The remote I/O slaves will operate according to the settings in the slaves.
• If a power supply error occurs.
• When an Incorrect Power Supply Unit Connected error occurs.
• When a CPU watchdog timer error or CPU reset occurs
• When a Controller error in the major fault level occurs.
• While the CPU Unit is startup status until RUN mode is entered after the
power is turned ON.
External safety measures must be provided to ensure safe operation of the sys-
tem in such cases.
• If external power supplies for slaves or other devices are overloaded or short-
circuited, the voltage will drop, outputs will turn OFF, and the system may be
unable to read inputs. Provide external safety measures in control with monitor-
ing of external power supply voltage as required so that the system operates
safely in such a case.
• Unintended outputs may be performed when an error occurs in variable memory
or memory for CJ-series Units. As a countermeasure for such problems, exter-
nal safety measures must be provided to ensure safe operation of the system.
• Provide measures in the communications system and in the user program to
ensure safety in the overall system even if errors or malfunctions occur in data
link communications or remote I/O communications.
• If a communications interference occurs for remote I/O or if a major fault level
error occurs, output status will be determined by the specifications of the exter-
nal output device. Confirm the operating specifications for communications
errors and major fault level errors and implement suitable safety measures. Cor-
rectly set all of the settings in the slaves and Units.
• You must implement fail-safe circuits to provide sufficient protection in the event
that abnormal signals occur as the result of broken signal lines or momentary
power interruptions. Not doing so may result in serious accidents due to incor-
rect operation.
NJ-series CPU Unit Hardware User's Manual (W500)
WARNING
4 Installation and Wiring
4
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