Overview of transition conditions on contouring (blending and transition modes)

If more than one motion FB is executed, the traversed path and the velocity profile will depend on the transition and blending processes transferred to the FBs.

The table below provides an overview of the permitted transitions:

BufferMode	TransitionMode	Description
mcAborting		Aborts the current active motion command and starts a separate motion command.
mcBuffered		The motion command only becomes active when all the previously commanded motions have been executed. When the job is completed, the velocity of the axis group is 0. As a result there is no blending to the next motion job and therefore the “TransitionMode” input is not evaluated.
mcBlending Previous	TMNone	No blending curve is inserted between 2 commands of the motion FB. The transition velocity between 2 commands depends on whether the command of the 2nd FB changes the motion direction.
	TMConstantVelocity	A blending curve is inserted in all these cases. An FB with one of these values at the “TransitionMode” input is not executed immediately since the following NC block is required to calculate the blending curve. With the last FB in a chained sequence of FBs, Buffered value must be applied to the “BufferMode” input.
	TMCornerDistance
	TMMaxCornerDeviation
	TMConstDeviation
	TMIntermediatePoint
	TMDynamicOptimized

The following definitions for blending paths are contained in the PLCopen specification:

Blending curve:	Inserted curve which modifies the original programmed path (E1’ - S2’).
Pre-block	Motion block before the blending curve (S1 – E1)
Post-block	Motion block after the blending curve (S2 – E2)
Corner distance	Distance (d) from the start point of the blending curve (E1’) to the programmed target point (E1), see figure below.

Corner deviation

The shortest distance between the programmed corner point (E1/S2) and the blending curve, see figure below.