MC_MoveAbsolute

PLCopen motion icon

Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs. - Performs a single-axis move to a specified endpoint position Position means a point in space which is described by different coordinates. Depending on the used system and transformation it can consist of a maximum of six dimensions (coordinates).This means three Cartesian coordinates in space and coordinates for the orientation. In ACS there can be even more than six coordinates. If the same position is described in different coordinate systems the values of the coordinates are different..

Inputs

Input

Data Type

Range

Unit

Default

Description

Execute

BOOL

0, 1

N/A

No default

On the rising edge The transition of a digital signal from low to high. AKA: positive edge., request to queue the move.

Axis

AXIS_REF

1, 256

N/A

No default

Name of a declared instance of the AXIS_REF library function A function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances..

See Axis Name and Number.
See AXIS_REF Structure.

Position

LREAL

See Description.

User units

No default

Endpoint position.

If Rollover Position is nonzero, this value must be in the range 0 <= Position < Rollover Position.
- See Rollover for more information.
When not in Rollover mode, the input accepts a 64-bit floating point value.
When converted to feedback units, the range is [-2⁵¹, 2⁵¹-1].

Velocity For a group of axes this means: In ACS the velocities of the different axes. In MCS and PCS it provides the velocity of the TCP

LREAL

No range

User unit/sec

No default

Velocity setpoint The target value that an automatic control system (e.g., PID controller) aims to reach..

Acceleration A change in velocity over time. Because velocity is a vector, it can change in two ways: a change in magnitude and/or a change in direction. In one dimension, acceleration is the rate at which something speeds up or slows down. However, more generally, acceleration is a vector quantity expressing the change with time of the velocity both in magnitude and in direction. See these Wikipedia articles for more information: http://en.wikipedia.org/wiki/Velocity http://en.wikipedia.org/wiki/Euclidean_vector http://en.wikipedia.org/wiki/Rate_(mathematics)

LREAL

No range

User unit/sec²

No default

Trapezoidal: Acceleration rate.

S-curve: Maximum acceleration.

If Acceleration is not valid, the ErrorID is set to 21.
- See PLCopen Function Block ErrorIDs.
See Function Block Acceleration and Jerk Parameters.
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.

If Jerk is not valid, the ErrorID is set to 21.
- See PLCopen Function Block ErrorIDs.
See Function Block Acceleration and Jerk Parameters for more information.
See S-curve and Trapezoidal Acceleration / Deceleration.

Direction The orientation components of a vector in space.

SINT

0, 4

N/A

No default

When Rollover Position is zero, a value of 0 must be specified.

When Rollover Position is nonzero, a value of 1, 2, 3, or 4 must be specified.

Value	Description
0	No direction specification.
1	Positive direction. The axis travels in the positive direction to the endpoint.
2	Shortest distance. The axis travels in the direction that provides the shortest distance to the endpoint.
3	Negative direction. The axis travels in the negative direction to the endpoint.
4	Last direction. The axis travels to the endpoint in the same direction as its previous move.

If the Position input is the same as the axis's current position, then:

If Direction = 2 (shortest distance):
- The axis does not move.
- The Done output goes high indicating that the move has been completed.
If Direction = 1, 3, or 4:
- The axis travels in the specified direction, through one rollover cycle.
- The axis arrives back at the same position.

BufferMode

SINT

0, 5

N/A

No default

0 = Abort.
1 = Buffer.
2 = Blend A way that consecutive function blocks cooperate in the transition from the first to the next. to active.
3 = Blend to next.
4 = Blend to low velocity.
5 = Blend to high velocity.
See Buffer Modes.

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.
See Call Function Blocks Multiple Times in the Same Cycle if using a dual-core controller.

See Main about how this function is used in the Hole punch project.

Figure 1: MC_MoveAbsolute

Time Diagram

These images show two examples of the combination of two absolute move A positioning movement referenced to a fixed original position. Example: If a stage is positioned at +500 mm, an absolute move to +300 mm would result in a move of 200 mm towards the origin (in the negative direction). 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 position 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 An asynchronous signal from hardware indicating the need for attention or a synchronous event in software indicating the need for a change in execution. and aborted by the Test signal during the constant velocity of the first FB.
- The second FB moves directly to the position 10000 although the position of 6000 is not yet reached.

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_MoveAbsolute S
T example *)
Inst_MC_MoveAbsolute( MovAbsReq, Axis1, 1234.567, 100.0, 100.0, 100.0, 0, 0, 0 );  //instance of MC_MoveAbsolute
MovAbsDone := Inst_MC_MoveAbsolute.Done;  //store done output into user defined variable
MovAbsBusy := Inst_MC_MoveAbsolute.Busy;
MovAbsActive := Inst_MC_MoveAbsolute.Active;
MovAbsAborted := Inst_MC_MoveAbsolute.CommandAborted;
MovAbsError := Inst_MC_MoveAbsolute.Error;
MovAbsErrID := Inst_MC_MoveAbsolute.ErrorID;