Mitsubishi Electronics 0 ユーザーズマニュアル

109

CHAPTER 11 TROUBLESHOOTING

11.
2 

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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.

Do the 

A LED and B LED turn on when a voltage is 

directly applied to the pulse input terminals for 

A and B?

If the 

A LED and B LED turn on, check the external wiring and the encoder, 

and make necessary corrections. If they do not turn on, the cause is a 
hardware failure. Please consult your local Mitsubishi representative, 
explaining a detailed description of the problem.

Is the external wiring for 

A and B correct?

Check the external wiring and make necessary corrections.

Is CH Count enable command (Y4, YC) on?

Turn on CH Count enable command (Y4, YC) using a program.

Is the pulse input method same as the pulse input mode 
setting specified in the intelligent function module switch 
setting?

Set the pulse input method same as the pulse input mode specified in the 
intelligent function module switch setting.

Is CH Counter function selection start command (Y6, 
YE) off or is a voltage not applied to the function start input 
terminal?

If the count disable function has been selected, turn off CH Counter function 
selection start command (Y6, YE) or the function start input terminal.

Is there an overflow error?

Execute a preset to clear the overflow error.

Is the external wiring for 

A and B correct?

Check the external wiring and make necessary corrections.

Even in 1-phase input, connecting an ABCOM terminal to a pulse signal can 
result in an incorrect count.
Reconnect the ABCOM terminal to the external power supply (5V/12V/24V) or 

the GND terminal. (

 Page 47, Section 6.3, Page 49, Section 6.4)

Is the maximum speed of the input pulses within the 
counting speed range specified in the intelligent function 
module switch setting?

Correct the counting speed configured in the intelligent function module switch 
setting according to the maximum speed of the input pulses.

Does the input pulse waveform meet the performance 
specifications?

Observe and check the pulse waveform with a synchroscope. If the input 
pulse does not meet the performance specifications, input pulses which meet 
the performance specifications.

Are the count value data handled in 32-bit signed binary in 
the program?

Correct the program so that the count value data are handled in 32-bit signed 
binary.

Are shielded twisted pair cables used for the pulse input 
lines?

Use shielded twisted pair cables for the pulse input lines.

Is the high-speed counter module affected by noise 
through the grounding area?

• Separate the grounding cable of the high-speed counter module from the 

grounded part.

• If the high-speed counter module touches the grounded part, separate it.

Are noise reduction measures taken in the control panel 
or for noise emitting devices?

Take noise reduction measures such as attaching a CR surge suppressor to 
the magnet switch.

Is there a sufficient distance between the high voltage 
equipment 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.

Are the count values of CH1 and CH2 same when the 
same number of pulses are input?

If the count values differ, the cause is a hardware failure. Please consult your 
local Mitsubishi representative, explaining a detailed description of the 
problem.

Was the preset function performed within the count range 
of the ring counter? (for the ring counter function only)

Reset the preset value within the count range and perform the preset function 
again.