MC_MoveRelative

PLCopen motion icon

Function Block - Performs a single-axis move of a specified distance relative to the actual position at the time of the start of execution.

Inputs

Input	Data Type	Range	Unit	Default	Description
Execute	BOOL	0, 1	N/A	No default	On the rising edge, request to queue the move.
Axis	AXIS_REF	1 to 256	N/A	No default	Name of a declared instance of the AXIS_REF library function. See Axis Name and Number. See AXIS_REF Structure.
Distance	LREAL	No range	User units	No default	Distance.
Velocity	LREAL	No range	User unit/sec	No default	Velocity setpoint.
Acceleration	LREAL	No range	User unit/sec²	No default	Trapezoidal: Acceleration rate. S-curve: Maximum acceleration. See S-curve and Trapezoidal Acceleration / Deceleration.
Deceleration	LREAL	No range	User unit/sec²	No default	Trapezoidal: Deceleration rate. S-curve: Unused. See S-curve and Trapezoidal Acceleration / Deceleration.
Jerk	LREAL	No range	User unit/sec³	No default	Trapezoidal: 0 (zero). S-curve: Constant jerk. See S-curve and Trapezoidal Acceleration / Deceleration.
BufferMode	SINT	0, 5	N/A	No default	0 = Abort. 1 = Buffer. 2 = Blend to active. 3 = Blend to next. 4 = Blend to low velocity. 5 = Blend to high velocity. See Buffer Modes for detailed information.

Outputs

Output	Data Type	Range	Unit	Description
Done	BOOL	No range	N/A	Indicates the move completed successfully. The Command Position has reached the endpoint.
Busy	BOOL	No range	N/A	High from the moment the Execute input goes high until the time the move is ended.
Active	BOOL	No range	N/A	Indicates this move is the Active move.
CommandAborted	BOOL	No range	N/A	Indicates the move was aborted.
Error	BOOL	No range	N/A	Indicates either: An invalid input was specified. The move was terminated due to an error.
ErrorID	INT	No range	N/A	Indicates the error if Error output is TRUE. See PLCopen Function Block ErrorIDs.

Remarks

This function block starts a motion-related action and stores data for calculations and error checking.
If using a dual-core controller, see Call Function Blocks Multiple Times in the Same Cycle.

See Function Blocks - General Rules about how inputs and outputs work.
See Main about how this function is used in the Hole punch project.

Figure 1: MC_MoveRelative

Time Diagram

These images show two examples of the combination of two relative move Function Blocks (FBs).

The left part of the diagram illustrates when the second FB is called after the first one.
- If the first reaches the commanded position of 6000, and the velocity is 0 (zero), the output Done causes the second FB to move to the distance 10000.
The right part of the diagram illustrates when the second move FB starts the execution while the first FB is still executing.
- The first motion is interrupted and aborted by the Test signal during the constant velocity of the first FB.
- The second FB adds on the actual position of 3250 the distance 4000 and moves the axis to the resulting position of 7250.

Figure 2: Time Diagrams: First and Second FBs

Figure 3: Time Diagram

FBD Language Example

Not available.

FFLD Language Example

IL Language Example

Not available.

ST Language Example

(* MC_MoveRelative ST example *)
Inst_MC_MoveRelative( MovRelReq, Axis1, 10.0, 200.0,150.0, 150.0, 0,0 );
MovRelDone := Inst_MC_MoveRelative.Done;  //store Done output into user defined variable