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Appendix - 51
MELSEC-
A
APPENDICES
Trouble type Questions/Trouble Remedy No.
Error compensation
The machine only moves to
"10081230", although positioning
with a command value of
"10081234" carried out.
How can the error be
compensated?
The following values are currently
set.
Pr.2 No. of pulses per
rotation = 8192
Pr.3 Movement amount
per rotation = 8000
Reset
Pr.3 and Pr.2 in the following order.
1) Calculate "8192/8000
10081230/10081234".
2) Obtain the reduced value.
3) Set the numerator in " Pr.3 Movement amount per
rotation", and the denominator in "
Pr.2 No. of
pulses per rotation".
20
Zero point return
When carrying out a count
method machine zero point
return, the message "Leave
Sufficient Distance From The
Zero Point Position To The Near-
Point Dog OFF." appears. Is there
a problem
if the distance is short?
The near-point dog must be set to turn OFF at a position
after the zero point is passed.
(When the machine zero point return is started on the
near-point dog ON in a count method machine zero point
return, the machine enters a normal machine zero point
return operation after returning to the near-point dog OFF
region.)
(If the near-point dog is turned OFF before the zero point,
and the machine zero point return is started between the
near-point dog OFF position and the zero point, the
machine will mistakenly interpret that its current position is
before the near-point dog ON position, and it will pass
over the zero point and continue moving.)
21
In the near-point dog method
machine zero point returns, the
stop positions are not uniform.
Carry out the following measures.
1) Separate the near-point dog signal and zero point
signal detection positions.
2) Lower the values in "
Pr.48 Zero point return
speed" and "
Pr.49 Creep speed".
3) Confirm whether the zero point signal and near-point
dog signal turn ON normally.
4) Check that there is no play (backlash) in the machine
system.
22
Can the machine zero point return
be carried out with the zero point
return retry function when it is
started with the near-point dog ON
and the upper/lower limit OFF?
A "Hardware stroke limit error" will occur and the
operation will not be carried out.
(The machine will interpret any position where the near-
point dog is ON as being within the working range, and
that the upper/lower limit is ON.)
23
Are ABS and INC positioning
possible without carrying out a
zero point return?
They are possible.
In this case, the position where the power is turned ON is
handled as the current feed position "0".
24
After a zero point return, the zero
point return request flag
sometimes turns ON for no
apparent reason.
The zero point return request flag turns ON in the
following cases.
1) When the remote station READY signal turns from
OFF to ON.
2) When a machine zero point return is carried out.
3) When the drive unit power is turned OFF.
If no problem is found when the above are checked, then
it is possible that the communication is being interrupted
by "a fault in the cable", "noise influence", etc.
25
The zero point return complete flag
(RX(n+2)0, RX(n+5)0) sometimes
turns ON when it shouldn't be ON.
Check whether the drive unit READY signal is weak or the
power supply is unstable.
26