# DefaultCoordinatedAccelLimit Parameter

Default Value: 0.0

Minimum Value: 0.0

Maximum Value: None

Units: dominant acceleration

Type: double

IMPORTANT: This parameter applies only when you use rate-based ramping. For more information about ramping, refer to the Coordinated Speeds section of Motion Setup Functions.

The DefaultCoordinatedAccelLimit parameter specifies the maximum acceleration of all dominant axes at non-tangent locations of a motion path. A non-tangent location occurs when two coordinated moves meet at a non-tangent angle. If you specify a nonzero value for this parameter, the controller decreases the speed of coordinated motion, such as MoveCcw(), MoveCw(), and MoveLinear() functions, before the non-tangent location. Thus, the controller makes sure that the accelerations of all dominant axes at the non-tangent location are at or below the DefaultCoordinatedAccelLimit value.

By default, the DefaultCoordinatedAccelLimit parameter causes the controller to decrease the speed of coordinated moves to a lower speed that is nonzero. To make sure that the controller always decreases the speed of coordinated moves to zero, change the setting of the CoordinatedAccelLimitSetup Parameter to Decel to Zero Velocity.

The DefaultCoordinatedAccelLimit parameter specifies the maximum acceleration of each axis in a move, not the coordinated acceleration of the move. To determine the value to use for this parameter, start by setting this parameter to the same value as the DefaultCoordinatedRampRate Parameter. Then adjust the value as necessary.

The DefaultCoordinatedAccelLimit parameter limits dominant axis accelerations only at non-tangent parts of a motion path. To limit dominant axis accelerations during the curved parts of a motion path, use the DefaultCoordinatedCircularAccelLimit Parameter. To limit dependent axis accelerations, use the DefaultDependentCoordinatedAccelLimit Parameter.

For Example - Limiting Axis Acceleration to a Nonzero Speed

Point B is a non-tangent location (90° angle). The DefaultCoordinatedAccelLimit parameter causes the controller to decrease the coordinated speed from point A to point B in order to prevent an over-acceleration of X and Y at point B.

Point C is also a non-tangent location (30° angle). The DefaultCoordinatedAccelLimit parameter causes the controller to decrease the coordinated speed from point B to point C in order to prevent an over-acceleration of X and Y at point C.

Because the angle at point B is greater than the angle at point C, the coordinated speed is less at point B than it is at point C.

Motion Path with Non-Tangent Locations IMPORTANT: You must reset the controller for these changes to have an effect.