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9 TROUBLESHOOTING
9.3 When the QD62(E/D) Does Not Normally Count
Check item
φ
Is the external wiring of
Is the maximum speed of input pulse within the range
of the counting speed made on the intelligent function
module switch setting?
Does the input pulse waveform meet the performance
specifications?
Are the count value data treated in 32-bit binary in the
sequence program?
Are the shielded twisted pair cables used for pulse
input wiring?
Doesn't any noise come from the ground part of the
QD62(E/D)?
Has the measures against noise been taken to the
adjacent devices and inside the control panel?
Is the distance between the high voltage equipment
and pulse input line kept enough?
Has the same count been input for both CH1 and
CH2 and are the count values the same?
9 - 3
φ
A and
B normal?
Check the external wiring and correct the error.
The module may miscount when ABCOM terminal is connected to
a pulse signal.
Connect the ABCOM terminal with external power (5V/12V/24V) or
GND terminal (refer to Section 4.4.2).
Correct the counting speed setting in the intelligent function
module switch setting to meet the maximum speed of the input
pulse.
Check the pulse waveform with synchronoscope. When the input
pulse does not meet the performance specifications, input the
pulse which meets the performance specifications.
Correct the sequence program so that the count value data can be
treated in 32-bit binary.
Use the shielded twisted pair cables for pulse input wiring.
Separate the ground cable of the QD62(E/D) from the ground part.
When the QD62(E/D) case touches to the ground part, separate it.
Take noise reduction measures (e.g. attach a CR surge
suppressor to the magnet switch).
Bundle the pulse input lines and put them in a single tube, and
keep a distance of 150 mm (5.91 inch) or more with the power line
even inside the control panel.
When the count values are different, this is a hardware error.
Contact our branch office or distributor for consultation and give
details of the problem.
MELSEC-Q
Action
9 - 3
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