MC_MoveDirectRelative (FB)¶

FUNCTION_BLOCK FINAL MC_MoveDirectRelative

This function block commands a movement of an axis group by the specified relative distance in the specified coordinate system .

Each axis is moved to its target position independently, the movement is only synchronized such that all axes reach the target at the same time. This means that the path travelled by the TCP depends on the kinematic transformation used. In general, it will not be a line. (This is called a point to point or PTP movement.)

Note

The path travelled by the TCP results indirectly from the movement of the axes and the kinematic transformation. It is not easy to predict the path based on the start- and end-position of the movement. However, once a PTP movement has been taught-in, the path is not modified by changing the override, interrupting, halting, or stopping. In more detail:

The path is independent of the override.
The path is independent of the limits of the axes (limits for velocity, acceleration, deceleration, and jerk). The only exception is for determining the cutoff points in TMStartVelocity mode.
In TMCornerDistance mode, the path is independent of the blending type (BlendingHigh/Low/Previous/Next).
The path is not left on halt or stop (MC_GroupHalt/MC_GroupStop).
The path is not left on interrupt or continue (MC_GroupInterrupt/MC_GroupContinue).
The acceleration, constant velocity, and deceleration phase for all axes begins and ends at the same time.

Note

The velocity/acc-/deceleration/jerk limits of each axis are properties of each axis and not specified within this function block. See also inputs VelFactor, AccFactor and JerkFactor.
The transition mode TMCornerDistance is only supported if the start- and end-position of the movement are given in the ACS. Otherwise, an error is reported.

The following example shows the behaviour of MC_MoveDirectRelative.

All positions are related to the MCS:

Starting at position p0 (10; 10) a MC_MoveLinearAbsolute to position p1 (80; 35) is commanded.
While the TCP is moving towards p1, the MC_MoveLinearAbsolute command is aborted by a MC_MoveDirectRelative command. The actual position of the TCP, when MC_MoveDirectRelative becomes active, is (44.5; 21.63).
The TCP leaves the line p0 .. p1 and moves to the new target position p2 (54.5; 41.63). The resulting trajectory depends on the kinematic transformation of the axis group.

../../../_images/MC_MoveDirectRelative_Example.png

InOut:

Scope	Name	Type	Initial	Comment
Inout	`AxisGroup`	AXIS_GROUP_REF_SM3		Reference to a group of axes
Input	`Execute`	`BOOL`		Start the motion at rising edge
	`Distance`	SMC_POS_REF		Distance in the specified coordinate system. The relative orientation in Distance.A/.B/.C is interpreted as a rotation. The resulting orientation of the end position is then determined as Rot_End(u) = Rot_Rel(Rot_Start(u)) where Rot_Rel is the rotation and Rot_Start is the rotation that belongs to the start position of the movement. Note The rotation that belongs to an orientation is the function that transforms direction vectors u from the TCP coordinate system to the base coordinate system `CoordSystem`. The corresponding rotation matrix can be computed from A/B/C as R = Rz(A) * Ry(B) * Rz(C).
	`MovementType`	SMC_PTP_MOVEMENT_TYPE		Type of PTP movement. No longer supported. This obsolete input will be removed in future versions.
	`CoordSystem`	SMC_COORD_SYSTEM		Applicable coordinate system
	`BufferMode`	`MC_BUFFER_MODE`		Defines the chronological sequence of the FB relative to the previous block.
	`TransitionMode`	MC_TRANSITION_MODE		Defined the blending in case of a blending buffer mode
	`TransitionParameter`	ARRAY [0..(SMC_RCNST.MAX_TRANS_PARAMS - 1)] OF LREAL		Parameters for blending
	`VelFactor`	`LREAL`	1	The maximum velocity of each axis is multiplied by this factor, which must be in the range ]0, 1].
	`AccFactor`	`LREAL`	1	The maximum acceleration of each axis is multiplied by this factor, which must be in the range ]0, 1].
	`JerkFactor`	`LREAL`	1	The maximum jerk of each axis is multiplied by this factor, which must be in the range ]0, 1].
	`TorqueFactor`	`LREAL`	1	The maximum torque of each axis is multiplied by this factor, which must be in the range ]0, 1]. A dynamic model must have been set using SMC_GroupSetDynamics for this factor to have an effect.
Output	`Done`	`BOOL`		Commanded end positions reached for all axes
	`Busy`	`BOOL`		The FB is not finished
	`Active`	`BOOL`		Indicates that the FB has control on the axis
	`CommandAborted`	`BOOL`		Command is aborted by another command
	`CommandAccepted`	`BOOL`		The command has been accepted by the axis group. If the output becomes `TRUE`, the function block instance can be used to command the next movement with a new rising edge on `Execute`. While the output is `FALSE`, keep calling the function block without a new rising edge of `Execute`. The output is reset to `FALSE` on a falling edge of `Execute`.
	`Error`	`BOOL`		Signals that an error has occurred within the function block
	`ErrorID`	`SMC_ERROR`		Error identification
	`MovementId`	`SMC_Movement_Id`		The unique identifier of the movement. Valid if `CommandAccepted` or `Done` is `TRUE`.