Rockwell Automation 1771-QA Stepper Positioning Assembly User Manual - Manual (Page 70)

3–48 Programming and Operation
Publication 1771-UM002A–EN–P – May 2000
The parameters of the equation (IR, FR, RT and DELPOS) and a
sketch of the move are shown in Figure 3.22.
Figure 3.22
Last Move in a Continuous Mode
IR
Rate
FR
RT DT
DEL POS
Position
Final
Position
Start
Position 10531
20 ms
Solution: Write down the known facts.
RT = 6 seconds
IR = 12k pulses per second (final rate of previous move)
FR = 6k pulses per second
DELPOS = 62k pulses (742k pulses - 680k pulses)
6(6k + 12k)
+ 6k + 0.02 < 62k
2 2
DT
+ 6k + 0.02 < 62k
2
DT
54k
6k + 0.02 < 8k
2
DT
+ 0.02 < 1.33
2
DT
< 1.31
2
DT
Therefore, a decel time of 2 seconds is acceptable for the move.
Reversing Direction During a Continuous Sequence
In order to reverse direction during a positioning sequence in the
continuous mode, a move to 0Hz rate must be achieved. The
procedure for achieving a 0Hz rate as stated in the paragraph titled
“Decel and Position Considerations for a 0Hz Rate Move” should be
followed.