User manual

Chapter 1 Introduction to the 2762-17
12
ADVANCED MICRO CONTROLS INC.
Positioning Setup Parameters (continued)
Stop Offset
Once on the correct side of the Target Position,
the Stop Offset defines the position at which the
motor outputs are turned off at the end of the move
profile. The load then coasts to the Target
Position.
The Stop Offset can be programmed to any
value between one and (Low Speed Offset - 1). If
the Low Speed Offset equals zero, the Stop Offset
can be programmed to any value between one and
(Overshoot Offset -1).
If the load is not at Target Position at the end of
the move profile the 2762-17 adjusts the Stop
Offset by the difference between the actual
position and the Target Position. The module will
then back out to the overshoot position and run the
profile again with the adjusted Stop Offset. The
2762-17 will not allow the adjusted value of the
Stop Offset to be greater than the Overshoot
Offset.
When initiated from the keyboard, the 2762-17 will adjust and re-run the profile a maximum
of three times before issuing an error message. When initiated from the backplane, the module
will adjust and re-run the profile the number of times specified by the Retry Value parameter
before issuing an error message. If the Target Position is reached, the 2762-17 stores the
adjusted Stop Offset if it is within the range listed above.
Target Range
The Target Range defines a dead band around
the Target Position. If the position at the end of a
move profile is (Target Position ± Target Range)
then the move profile is considered complete.
The Target Range can be programmed to any
value between zero and Full Scale Count.
As shown in Figure 1.9, the Target Range is
added to and subtracted from the Target Position
when determining the dead band. For example,
assume a Target Position of 10,000 and a Target
Range of five. The acceptable positions at the end
of the move profile are then 9,995 to 10,005.
Target
Overshoot
Negative Approach
Overshoot
Target
Positive Approach
.601 in
Stop
Offset
Low Speed
Low Speed
Stop
.601 in
Stop
Offset
Stop
Figure 1.8 Stop Offset
Target
Overshoot
Negative Approach
Target
Positive Approach
Low Speed
Stop
.200 in
± Target
Range
.200 in
± Target
Range
Overshoot
Low Speed
Stop
Figure 1.9 Target Range