Mitsubishi Electric MELSEC-L LD75D, User Manual

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APPENDICES
A
Appendix
8
ME
LSE
C
E
xplanat
ion
of
Pos
itioning T
e
rm
s
SUDDEN STOP
A stop carried out in a shorter time than the deceleration time designated in the parameters.
NEAR-POINT DOG
This is a switch placed before the OP. When this switch turns ON, the feedrate is changed to the creep speed.
Because of that, the time that this switch is ON must be long enough to allow for the time required for
deceleration from the feedrate to the creep speed.
OP
This is the reference position for positioning. Positioning cannot start without a reference point.
The OP is normally set to the upper or lower stroke limit.
OP SHIFT FUNCTION
The OP position can be shifted in the positive or negative direction by executing a machine OPR and determining
the shift amount from the machine OPR complete position.
An OP can be set at a position besides the OP position, or outside the dog switch.
OPR METHOD
The OPR methods are shown below. The method used depends on the machine structure, stopping accuracy,
etc.
OPR can be carried out when the OPR parameters are written.
• Near-point dog method
• Stopper method
• Count method
OPR PARAMETER
This parameter is required when returning to the OP. It is determined by the machine side design, so subsequent
changes of this parameter must be accompanied by changes in the machine design.
The OP is the reference for positioning operations, so if the OP is lost due to a power failure during positioning, or
because the power is turned OFF and the machine is moved manually, etc., it can be restored by carrying out an
OPR. When a machine OPR command is issued, the machine will move in search of the near-point dog
regardless of the current value, and will stop at the OP. At this time, the current value will be rewritten to the OP
address. Data cannot be written during positioning. With the LD75, data is always written for all axes (from 1 to 4
axes).
Refer to the term "NEAR-POINT DOG".
OPR REQUEST
This signal turns ON when there is an error with the LD75. It will turn ON in the following situations.
• When the power is turned ON
• When the PLC READY signal turns from OFF to ON
• When the machine OPR starts
• When the drive unit READY signal turns from ON to OFF
The user judges whether to carry out a machine OPR in the above situations.
Term Description
Full speed
Sudden stop
Time
Deceleration time
ON OFF
Feedrate
Creep speed
Time
Near-point dog
OP
This point is the reference.