Mitsubishi Electric QD75MH1, User Manual

Page: 802 / 834

Appendix - 53
MELSEC-Q
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
"
262144PLS
•
"
Pr.3
Movement amount
per rotation" 8000
µ
m
Reset
Pr.3
and
Pr.2
in the following order.
1) Calculate "262144/8000
×
10081234/10081230".
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".
18
When carrying out a count-method
machine OPR, the message
"Leave Sufficient Distance From
The OP 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 OP is passed.
(When the OPR is started on the near-point dog ON in a
count-method machine OPR, the machine enters a
normal machine OPR operation after returning to the
near-point dog OFF region.)
(If the near-point dog is turned OFF before the OP, and
the machine OPR is started between the near-point dog
OFF position and the OP, the machine will mistakenly
interpret that its current position is before the near-point
dog ON position, and it will pass over the OP and
continue moving.)
19
In the near-point dog method
machine OPR, the stop positions
are not uniform.
Carry out the following measures.
1) Separate the near-point dog signal and zero signal
detection positions.
2) Lower the values in
"
Pr.46
OPR speed
"
and
" Pr.47
Creep speed
"
.
3) Confirm whether the zero signal and near-point dog
signal turn ON normally.
4) Check that there is no play (backlash) in the machine
system.
20
Can the machine OPR be carried
out with the OPR 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.)
21
Are ABS and INC positioning
possible without carrying out an
OPR? They are possible.
In this case, the position where the power is turned ON is
handled as the current feed value "0".
22
OPR
After an OPR, the OPR request
flag sometimes turns ON for no
apparent reason.
The OPR request flag turns ON in the following cases.
1) When the power is turned ON.
2) When the machine OPR has not been executed at the
absolute position system.
3) When the "absolute position lost" ( Md.108 Status: b4)
turns ON in the absolute position system.
4) When the " Pr.114 Rotation direction selection" is
changed.
5) When an OPR operation starts.
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 bus cable", "noise influence", etc.
23