Mitsubishi Electronics QD75MH2 ユーザーズマニュアル

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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"   8000µm 
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