PMAC Product Guide Linear Blended Moves The move time is set directly by TM or indirectly based on the distances and feedrate (F) parameters set: TM100 X3 Y4 or FRAX(X,Y) X3 Y4 F50 msec 100 50 2 4 2 3 I190 TM = = + ⋅ = 5000 50 If the move time calculated above 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 results in the minimum move time of a linearly interpolated move. If the TA programmed results are less than twice the TS programmed, TA , 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- Ѕ 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. • If TM • If TA • If TA i+1 > 2*(TM i - Ѕ TA i ), TA i+1 = 2*(TM i - Ѕ TA i ) 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. 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 2. The two move commands are plotted without blending, placing a DWELL0 command in between the two moves: Motion Programs 75