MC_MoveAbsolute

PLCopen motion icon

 Function Block - Performs a single-axis move to a specified endpoint position.

Inputs

Input

Data Type

Range

Unit

Default

Description

Execute

BOOL

FALSE, TRUE

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.

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

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.

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.

Direction

SINT

0 to 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 to 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

FALSE, TRUE

N/A

Indicates the move completed successfully.
The Command Position has reached the endpoint.

Busy

BOOL

FALSE, TRUE

N/A

High from the moment the Execute input goes high until the time the move is ended.

Active

BOOL

FALSE, TRUE

N/A

Indicates this move is the Active move.

CommandAborted

BOOL

FALSE, TRUE

N/A

Indicates the move was aborted.

Error

BOOL

FALSE, TRUE

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

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 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 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;

See Also