Safety Measures - Panasonic FP-XH M8N16PD User Manual

Wiring of Power Supply and General-purpose I/O Parts

5.5 Safety Measures

5.5.1 Safety Measures
 Precautions regarding system design
In certain applications, malfunction may occur for the following reasons:
• Power on timing differences between the PLC system and input/output or mechanical power
apparatus.
• Response time lag when a momentary power drop occurs.
• Abnormality in the PLC unit, external power supply, or other devices.
In order to prevent a malfunction resulting in system shutdown choose the adequate safety
measures listed in the following:
 Interlock circuit
When a motor clockwise/counter-clockwise operation is controlled, provide an interlock circuit
externally.
 Emergency stop circuit
Provide an emergency stop circuit to the PLC externally to turn off the power supply of the
output device.
 Start up sequence
The PLC should be operated after all of the outside devices are energized. To keep this
sequence, the following measures are recommended:
• Turn on the PLC with the mode selector set to the PROG. mode, and then switch to the RUN
mode.
• Program the PLC so as to disregard the inputs and outputs until the outside devices are
energized.
Note) In case of stopping the operation of the PLC also, have the input/output devices turned
off after the PLC has stopped operating.
 Grounding
When installing the PLC next to devices that generate high voltages from switching, such as
inverters, do not ground them together. Use an exclusive ground for each device which should
be grounded at a grounding resistance of 100Ω or less.
Electric shock prevention

The terminal block cover must be used for preventing electric shock.
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