MELSEC-A
11. TROUBLESHOOTING
11 - 1
11. TROUBLESHOOTING
11.1 Count Value Is Incorrect
The following table lists check items for use when the count value is incorrect.
Check Item Corrective Action
Is the pulse input mode consistent with the pulse
input setting in the remote register?
Make the pulse input mode consistent with the pulse input
setting in the remote register.
Is the sequence program data processed in 24-bit
binary?
Correct the sequence program so that the data is processed
in 24-bit binary.
Is the terminal for pulse input wired using a
shielded twisted pair cable?
Use a shielded twisted pair cable for to wire a terminal for
pulse input.
Does noise enter through the ground of the high-
speed counter module?
• Disconnect the high-speed counter module from the ground.
• If the high-speed counter module is in contact with the
ground, separate it from the ground.
Have adequate measures been taken against
noise in the panel or noise resulting from the other
equipment?
Provide CR surge suppression to magnetic switches, etc.
Is sufficient distance provided between heavy
current equipment and counter input line?
Wire the pulse input line independently, and separate in-
panel wiring 150mm (5.91 inch) or more from power line.
Is the count value the same at CH1 and CH2 after
the same count value was entered?
If the count values are different, the hardware is faulty.
Please consult your local Mitsubishi representative.
Does the input pulse waveform match the
performance specifications?
Monitor and confirm the pulse waveform using a
synchroscope. If the waveform does not match the
specifications, enter pulses of a correct waveform.
11.2 Count Operation Is Not Performed
The following table lists check items for use when count operation is not performed.
Check Item Corrective Action
Is the external wiring of phases A and B
correct?
Check the external wiring and make correction.
When a voltage is applied directly to the pulse
input terminals of phases A and B, are the
LEDs of phases A and B lit?
• If they are lit, check the external wiring and pulse generator
and make correction.
• If they are not lit, the hardware is faulty. Please consult your
local Mitsubishi representative.
Is the count enable command {RY(n+1)4
(RY(n+1)B} on?
Switch on the count enable command {RY(n+1)4 (RY(n+1)B}
using the sequence program.
Does the master module indicate an error? If the master module is in error, refer to the troubleshooting
procedure of the manual of the master module used and
make operation normal.
Is the counter function selection start command
{RY(n+1)6 (RY(n+1)D)} on or a voltage applied to
the F.START terminal?
When the count disable function has been set by the counter
function selection, switch off {RY(n+1)6 (RY(n+1)D)} or
F.START terminal.
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