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14 TROUBLESHOOTING
14.5 Troubleshooting by Symptom
A multi function counter does not start counting or does not
count properly
The module does not start counting
The module does not count properly
Check item
Action
Has Count Enable been set to ON?
Set Count Enable to ON using a program or the configuration tool.
Is any LED of the CPU module indicating an error?
If the LED indicates an error, refer to the troubleshooting in the manual for the
CPU module used and take corrective actions to restore normal operation of
the CPU module.
Is the external wiring for
Φ
A and
Φ
B 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
Are the current value or other values read in increments of one word (16 bits)
using a program when 32-bit counter timer blocks are used?
Read the values of two words (32 bits) in a batch.
Was the preset function performed within the count range of a counter?
Reset the preset value within the count range and perform the preset function
again.
Is the filter time setting of external input blocks correct?
Check the filter time setting and make necessary corrections.
When the same pulse is input to the multi function counter blocks that have
the same links, is the same value counted?
If the count values are different, the possible cause is a failure of the module.
Please consult your local Mitsubishi representative.
Does the input pulse wave satisfy the performance specifications?
Observe and check the pulse wave with a synchroscope. If the input pulse
does not satisfy the performance specifications, input pulses that satisfy the
performance specifications.
Is the external wiring with the SSI encoder correct?
Check the external wiring. (
Page 55 Example of external wiring with the
SSI encoder (serial communication))
Is the setting value of the SSI encoder block correct?
Check and correct the value according to the SSI encoder to be connected.
Is the cable length within the range of the maximum cable length?
Check the cable length and size. (
Page 55 Example of external wiring
with the SSI encoder (serial communication))
Or slow the SSI transmission speed.
Are shielded twisted pair cables used?
Use shielded twisted pair cables.
Does noise affect anything?
Take measures to reduce noise such as attaching a surge suppressor to the
magnet switch.
Is there a sufficient distance between the high voltage device and the signal
wires?
Wire the signal wires alone and keep them 150mm or more away from power
cables.
Summary of Contents for MELSEC-L Series LD40PD01
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