YASKAWA SVC - Position References

5.1 Motion Parameters
5.1.4 Position References
5-6
5.1.4 Position References
The target position for position control is set in the OL  1C setting parameter (Position Ref-
erence Setting). There are two different methods of setting the position reference: the absolute
value specification method, which sets the coordinate data for the target position directly, and
the incremental addition method, which adds the current travel amount to the previous position
reference value.
The parameters that are related to setting the position reference are listed in the following table.
The following table compares the merits and demerits of the incremental value addition and
absolute value specification methods.
Setting the Target Position for an Infinite-length Axis
There are two methods that you can use to set the target position when an infinite-length axis
is used.
In the following cases, use setting method 1 to set the target position.
• When executing a POSING command when no command (NOP) is being executed
Parameter
Type
Register
Address
Name Description Default
Setting
Parameters
OW
09
Bit 5
Position Ref-
erence Type
This parameter specifies the type of position reference
data.
0: Incremental value addition method
This method sets OL
1C to the current value of
OL
1C plus the current travel distance.
1: Absolute value specification method
This method sets OL
1C to the coordinate
value of the target position.
Setting Precautions
Always set this parameter to 0 when a motion pro-
gram is used.
0
OL
1C
Position Ref-
erence Set-
ting
This parameter sets the position data.
• If the incremental value addition method is used (i.e.,
if bit 5 in OW09 is set to 0), the current travel
distance (incremental amount) is added to the cur-
rent value of OL
1C.
OL
1C = OL1C + Incremental travel dis-
tance
Example:
If the current travel distance is 500 and the previous
value of OL
1C is 1,000, OL1C will equal
1,000 + 500 or 1,500.
• If the absolute value specification method is used
(i.e., if bit 5 in OW
09 is set to 1), this parame-
ter is set to the coordinate value of the target posi-
tion.
Example:
Set OL
1C to 10,000 to move to the position
10,000.
OL
1C = 10000
0
Position
Reference Type
Merit Demerit
Incremental value
addition method
It is not necessary to consider the relation-
ship between OL1C and the current
position when a move is canceled.
OL
1C does not equal the target posi-
tion, so the position reference can be difficult
to understand intuitively.
Absolute value
specification
method
The coordinate of the target position is
specified directly, making it easy to under-
stand.
The current position must be set in
OL
1C whenever the power supply is
turned ON or a move is canceled. If this
operation is not performed, the axis may
move suddenly when a movement motion
command is started.
This method also makes the target position
difficult to manage for infinite-length axes.