Allen-Bradley 1756 ControlLogix - Motion Disarm Watch (MDW)

Motion Event Instructions
Chapter 4
Rockwell Automation Publication MOTION-RM002H-EN-P-February 2018 243
The following figure shows rungs to redefine the axis position of a motion control
application program using the Motion Arm Watch (MAW) instruction.
Watch Position Example
The following example shows the ladder logic to:
• Create a watch position event
• Enable an output when the trigger condition occurs.
Rung 0:
This rung arms a watch position event for Axis_1 when the arm_ watch bit
transitions from false to true
When the MAW instruction begins executing, the Axis_1.WatchEvStatus bit
resets. This bit sets when the actual position of 500 in the forward direction.
Rung 1:
This rung enables the cut output when the watch position occurs. (The
MAW_1.PC bit sets when the watch position occurs.)
The Motion Disarm Watch (MDW) instruction is used to disarm watch position
event checking for the specified axis.
This information applies to the CompactLogix 5370, ControlLogix 5570,
Compact GuardLogix 5370, GuardLogix 5570, Compact GuardLogix 5380,
CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, and GuardLogix
5580 controllers. Controller differences are noted where applicable.
Use the Motion Disarm Watch (MDW) instruction to disarm watch-position
event-checking for an axis. This instruction has the effect of clearing both the
Watch Event Status and Watch Armed Status bits in the axis data structure.
Understand a Programming
example
Motion Disarm Watch (MDW)