Delta RMC151 - Manual (Page 795)

8 Command Reference
This topic describes only the advanced features of this command. For basic information
on using this command, see the Curve Start (86) command.
Absolute/Relative Curve Alignment
Curve alignment refers to the Y-values of the curve, which are the positions of the curve
axis:
Absolute
With Absolute curve alignment, the positions will be exactly as defined by the curve.
To choose absolute curve alignment, add +0 to the Options command parameter.
Relative
With Relative curve alignment, the Y-values will be relative to the Target Position of
the curve axis at the time the Curve Start Advanced command is sent. That is, the
Y-values in the Curve Data will be adjusted such that the Point 0 Y-value is set to
the current position of the axis. All the other Y-value points will be adjusted by the
same amount. To choose relative curve alignment, add +1 to the Options
command parameter.
Transitions
When using absolute curve alignment, the axis must be at the correct point in the curve
when the Curve Start Advanced command is issued. The correct point can be very difficult
to determine if the master is not at the starting point, and therefore, the Transition Rate
(56) command must be used to specify how the axis should get to the correct point when
this command is issued.
Absolute/Relative Master Alignment
Master alignment refers to the X-values of the curve, which are the positions of the
master:
Absolute
With Absolute master alignment, the x-values will be exactly as defined by the
curve. To choose absolute master alignment, add +2 to the Options command
parameter.
Absolute master alignment is intended for applications where the curve must occur
at an exact location based on the position of the master, such as in camming.
Relative
With Relative master alignment, the X-values will be relative to the master value at
the time the Curve Start Advanced command is sent. That is, the X-values in the
Curve Data will be adjusted such that the Point 0 X-value is set to the current value
of the master. All the other X-value points will be adjusted by the same amount. To
choose relative master alignment, add +0 to the Options command parameter.
Relative master alignment is intended for applications where the starting master
point of the curve may vary, which may be the case when the master is a conveyor
belt or a feed chain, such as in curve sawing. The Endpoint Behavior options for a
relative master are specifically designed for this type of use case.
Using _Time as an Absolute Master
The _Time register wraps every second through the range [0.000000, 1.000000). It can
be used as a master for curves that are to run based on time. When using _Time as an
absolute master, the _Time is assumed to be zero when the Curve Start Advanced
command is issued. Using a Master Offset will adjust the curve in time, effectively
delaying the curve, or beginning at some point in the middle of the curve.
Endpoint Behavior
The Endpoint Behavior specifies what happens to the curve axis if the master moves
outside of the X-value range defined by the curve data. For cyclic curves, the endpoints
are the beginning of cycle 0, and the end of the last cycle. Infinite cyclic curves will
continue until another motion command is issued to the axis.
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