Mitsubishi Electric MELSEC-L LD75D, User Manual

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APPENDICES
A
Appendix
9
Posit
ioni
ng
Cont
rol T
roubles
hoot
ing
Appendix 9
Positioning Control Troubleshooting
Trouble type Questions/Trouble Remedy No.
Parameter
Display reads "FFFFH" when a parameter is read
with GX Works2.
The CPU module power was turned OFF or the CPU module was
reset, etc., during flash ROM writing, which deleted the data in the
flash ROM.
Initialize the parameters, and reset the required parameters.
(

Page 610, Section 13.2)
1
How can the parameters be returned to their initial
values (default values)? Set the "[Cd.2] Parameter initialization request" to "1".
(

Page 610, Section 13.2)
2
A parameter error occurred although the parameter
was set correctly by GX Works2. The parameter may have been overwritten in the program.
Review the program.
3
Hardware stroke limit
The machine overruns if operating at high speeds
when the hardware stroke limit range is exceeded.
In the LD75, deceleration stops are executed after the machine
exceeds hardware stroke limit range. Because of this, more time is
required for the deceleration stop as the speed increases, and the
overrun becomes larger.
(The deceleration time becomes shorter at lower speeds, so the
overrun becomes smaller.)
4
When the machine exceeded the hardware stroke
limit range, positioning toward inside the range was
started, but the machine did not start.
Use a "JOG operation", " Inching operation" or "Manual pulse
generator operation" to return the machine to inside the hardware
stroke limit range.
(When the hardware stroke limit range is exceeded, positioning
will not start toward inside the range even when so commanded.
Once the range is exceeded, a return to inside the range can only
be executed using a "JOG operation", "Inching operation" or
"Manual pulse generator operation".)
5
degree
Exactly one rotation is required, but the setting
range for a "degree" unit setting is "0 to 359.999

".
Won't the rotation deviate by "0.00

1"?
Designate "360.000" in the INC control.
The motor will make exactly one rotation.
6
Movement amount per
pulse
If the "movement amount per pulse" is calculated as
written in the manual, settings smaller than the
basic parameter setting range cannot be carried
out. Set "movement amount per pulse" in the LD75 using the three
parameter values of [Pr.2] to [Pr.4].
Try setting the values following the explanations for each
parameter.
7
Override
Will an override setting value written before starting
be valid?
It will be valid. 8
During path control, will the override still be valid
after the point is passed?
It will still be valid. 9
How can the override be canceled? Set the "[Cd.13] Positioning operation speed override" to "100". 10
Acceleration/deceleration
time
How can the deceleration stop time during stopping
be shortened using the hardware stroke limit?
Set "1: Sudden stop" in the "[Pr.37] Stop group 1 sudden stop
selection", and reduce the setting value of "[Pr.36] Sudden stop
deceleration time".
11
The motor does not operate at "60000ms" although
the acceleration/deceleration time is set to
"60000ms".
The value set for the acceleration/deceleration time is the time
required for the machine to accelerate from speed "0" to the value
set in "[Pr.8] Speed limit value". Because of that, the
acceleration/deceleration time will also be shorter than "60000ms"
if the command speed value is smaller than the "[Pr.8] Speed limit
value". (
 Page 125, Section 5.2.2 (2))
12
Can each acceleration/ deceleration time be
individually set to trapezoidal or S-curve
acceleration/deceleration? The trapezoidal and S-curve acceleration/deceleration processing
is a common setting for all acceleration/deceleration times, so
individual setting is not possible. (

Page 596, Section 12.7.6)
13
The machine starts and stops suddenly when
carrying out JOG operations and positioning
operations.
(Using an MR-J2S servo amplifier.)
Review the parameter settings for acceleration/ deceleration time,
speed limit value, JOG speed limit value, JOG
acceleration/deceleration time, etc.
14
Simplified absolute
position detection system Are simplified absolute position detection systems
possible in the LD75 Positional deviation models?
They are possible if the models are used in combination with a
Mitsubishi Electric "AC Servo".
(Refer to

"AC servo User's Manual" for details.)
15
Positional deviation
The physical position position detection system
from the commanded position, although the
positioning is complete (and the monitored current
position is correct).
If the deviation counter value is not "0", the servo side is still
moving.
Increase the torque.
16