User guide

178 6000 Series Programmer's Guide
On-the-Fly Motion (pre-emptive GOs)
While motion is in progress, you can change these motion parameters to affect a new profile:
• Acceleration and S-curve Acceleration (A and AA)
• Deceleration and S-curve Deceleration (AD and ADA)
• Velocity (V)
• Distance (D)
• Preset or Continuous Positioning Mode Selection (MC)
• Incremental or Absolute Positioning Mode Selection (MA)
• Following Ratio Numerator and Denominator (FOLRN and FOLRD, respectively)
The motion parameters can be changed by sending the respective command (e.g., A, V, D, MC)
followed by the GO command. If the continuous command execution mode is enabled
(COMEXC1), you can execute buffered commands; otherwise (COMEXCØ), you must prefix
each command with an immediate command identifier (e.g., !A, !V, !D, !MC, followed by
!GO).
The new GO command pre-empts the motion profile in progress with a new profile based on
the new motion parameter(s). On-the-fly motion changes are applicable only for motion
started with the GO command, and not for motion started with other commands such as HOM,
JOG, JOY, PRUN or GOL.
On-the-fly motion changes are most likely to be used to change the velocity and/or goal
position of a preset move already underway. In the event that the goal position is completely
unknown before motion starts, a move may be started in continuous mode (MC1), with a
switch to preset mode (MCØ), a distance command (D), and a GO given later. In absolute
positioning mode (MA1) the new goal position given with a pre-emptive GO is explicit in the
D command. In incremental positioning (MAØ) the distance given with a new pre-emptive GO
is always measured from the at-rest position before the original GO. If a move is stopped
(with the S command), and then resumed (with the C command), this resumed motion is
considered to be part of the original GO. A subsequent distance given with a new pre-emptive
GO is measured from the at rest position before the original GO, not the intermediate stopped
position.
Programming Example: This program creates a 2-tiered profile (single-axis) that changes
velocity and deceleration at specific motor positions.
SCALE0 ; Disable scaling
DEL OTF ; Delete program (in case program is already in memory)
DEF OTF ; Begin definition of program
PSET0 ; Set position to zero
SCALE0 ; disable scaling
COMEXC1 ; Enable continuous command processing mode
MC0 ; Select preset positioning
MA0 ; Select incremental positioning
A20 ; Set accel to 20 revs/sec/sec
AD20 ; Set decel to 20 revs/sec/sec
V9 ; Set velocity to 9 revs/sec
D500000 ; Set distance to 20 revs
GO1 ; Initiate motion
WAIT(PM>100000) ; Wait until the motor position is > 100000 steps (4 revs)
V4 ; Slow down for machine operation
GO1 ; Initiate new profile with new velocity
WAIT(PM>450000) ; Wait until the motor position is > 450000 steps (18 revs)
AD5 ; Set decel for gentle stop
V1 ; Slow down for gentle stop
GO1 ; Initiate new profile with new velocity
END ; End program definition