106 Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018
Guidelines Details
In ladder diagram, toggle the rung
condition each time you want to
execute the instruction.
This is a transitional instruction:
In ladder diagram, toggle the rung-condition-in from cleared to set each time you want to execute the
instruction.
In structured text, condition the
instruction so that it only executes on
a transition.
In structured text, instructions execute each time they are scanned.
Condition the instruction so that it only executes on a transition. Use either of these methods:
• qualifier of an SFC action
• structured text construct
For more information, see Structured Text Syntax.
Use the jerk operands for S-curve
profiles.
Use the jerk operands when the instruction uses an S-curve profile.
You must fill in the jerk operands regardless of the profile.
Use % of Time for the easiest
programming and tuning of jerk.
For an easy way to program and tune jerk, enter it as a % of the acceleration or deceleration time.
For more information, see Tune an S-curve Profile.
Use Merge to cancel the motion of
other instructions.
How you want to handle any motion that’s already in process?
If You Want To And You Want To Then Set
Add the jog to any
motion already in
process
Merge = Disabled
Merge Speed = Programmed
The instruction ignores Merge Speed but you
must fill it in anyway.
End the motion from
other instructions and
just jog
Jog at the speed that you set
in this instruction
Merge = Disabled
Merge Speed = Programmed
Jog at the speed that the axis
is already moving
Merge = Enabled
Merge Speed = Current
The instruction ignores the value that you put in
the Speed operand.
Be careful if you start another jog
while the axis is already jogging.
If you start a new MAJ instruction while one is already in process, you can cause:
• an accelerating axis to overshoot its speed
• a decelerating axis to reverse
(revision 15 and earlier)
This happens if the MAJ instructions use an S-curve profile. The new MAJ instruction cancels the old MAJ
instruction. The axis uses the speed, acceleration, deceleration, and jerk of the new instruction.
For more information, see Troubleshoot Axis Motion.
Use an MAS instruction to stop the
jog.
Use an MCD instruction to change the
speed while jogging.
When MAJ (Merge = Enabled) is used on any axis associated with a coordinate
system and a coordinated motion instruction is running on it, Coordinate system’s
maximum deceleration is used to stop remaining axes. If the coordinate system
contains orientation axes, Coordinate system’s Orientation maximum
deceleration is used for stopping remaining Rx, Ry or Rz axes.
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