14 TROUBLESHOOTING
14.5 Troubleshooting by Symptom
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14
14.5
Troubleshooting by Symptom
Inputs from external devices are not performed
Incorrect inputs from external devices are performed
Outputs to external devices are not performed
The hardware logic does not function
Check item
Action
Is the LED0 on?
Check the external wiring and make necessary corrections.
Is the control of the hardware logic working?
When Hardware logic control flag (X4) is off, turn on Hardware logic control
start request (Y4) to start the hardware logic control.
Are the block layout and links between blocks in the hardware logic correct?
Check the block layout and links between blocks in the hardware logic and
make necessary corrections.
Check item
Action
Measures to
reduce
noise
Is the filter time setting of external input blocks correct?
Set the filter time of the external input blocks longer.
Have twisted pair shielded cables been used for the pulse
input cables?
Use twisted pair shielded cables for the pulse input cables.
Have measures to reduce noise been taken in the control
panel or for adjacent devices?
Take measures to reduce noise such as attaching a CR surge suppressor to
the magnet switch or other device.
Is there a sufficient distance between the high voltage device
and the pulse input cables?
Wire the pulse input cables alone when placing them in a duct, and keep a
distance of 150mm or more from the power cables in the control panel.
Is the module affected by noise through the grounding area?
Separate the grounding cable of the flexible high-speed I/O control module
from the grounding area.
Are the power cables and I/O cables bundled together?
Do not bundle the power cables and I/O cables together.
Is the external wiring connected to unused terminals?
Do not connect the external wiring to unused terminals.
Check item
Action
Is the LED1 on?
Check the block layout and links between blocks in the hardware logic and
make necessary corrections.
Is the external wiring correct?
Check the external wiring and make necessary corrections.
Is the control of the hardware logic working?
When Hardware logic control flag (X4) is off, turn on Hardware logic control
start request (Y4) to start the hardware logic control.
Are the block layout and links between blocks in the hardware logic correct?
Check the block layout and links between blocks in the hardware logic and
make necessary corrections.
Check item
Action
Is the control of the hardware logic working?
When Hardware logic control flag (X4) is off, turn on Hardware logic control
start request (Y4) to start the hardware logic control.
Are the block layout and links between blocks in the hardware logic correct?
Check the block layout and links between blocks in the hardware logic and
make necessary corrections.
Is the CPU module indicating an error?
If the CPU module is in an error status, refer to the troubleshooting in the
user's manual for the CPU module used and take corrective actions to restore
normal operation of the CPU module.
Summary of Contents for MELSEC-L Series LD40PD01
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