User`s manual

5.0 - Motion Programs
Page - 46
5.6 - Linear blended moves
- The move time is set directly by TM or indirectly based on the the distances and feedrate (F) parameters set:
- If the move time above calculated is less than the TA time set, the move time used will be the TA time instead. In this
case, the programmed TA (or 2*TS if TA<2*TS) results in the minimum move time of a linearly interpolated move.
- If the TA programmed results to be less than twice the TS programmed, TA<2*TS, the TA time used will be 2*TS
instead.
- The acceleration time TA of a blended move cannot be longer than two times the previous TM minus the previous TA,
otherwise the value 2*(TM- ½ TA) will be used as the current TA instead.
- The safety variables Ix16 and Ix17 will override these parameters if they are found to violate the programmed limits.
Example:
To illustrate how PMAC blends linear moves, a series of velocity Vs time profiles will be shown. The moves are defined
with zero S-curve components. The concepts described here could be used for non-zero S-curve linear moves.
1) Lets consider the following motion program code:
close
delete gather
undefine all
&1
#1->2000x
OPEN PROG 1 CLEAR
LINEAR ; Linear mode
INC ; Incremental mode
TA100 ; The acceleration time is 100 msec, TA
1
TS0 ; No S-curve component
TM250 ; Move time is 250 msec, TM
1
X10 ; Move distance is 10 units, 20000 counts
TA250 ; Acceleration \ deceleration of the blended move is 250 msec , TA
2
X40 ; Move distance is 40 units, 80000 counts
CLOSE
TM100
X3 Y4
FRAX(X,Y)
X3 Y4 F50 ;
msec 100
50
5000
50
2
4
2
3I190
TM ==
+⋅
=
or
- If TM < TA, TM = TA
- If TA < 2*TS, TA = 2*TS
- If TA
i+1
> 2*(TM
i
- ½ TA
i
), TA
i+1
= 2*(TM
i
- ½ TA
i
)
time
ve
l
½
TA½ TA T
M