MC_MoveAbsolute

MC_MoveAbsolute 1:

The function block MC_MoveAbsolute starts the positioning to an absolute target position and monitors the axis movement over the entire travel path. The "Done" output is set once the target position has been reached. Otherwise, the output "CommandAborted" or, in case of an error, the output "Error" is set.

MC_MoveAbsolute is predominantly used for linear axis systems. For
modulo axes the position is not interpreted as a modulo position, but as an absolute position in continuous absolute coordinate system. Alternatively, the function block MC_MoveModulo can be used for modulo positioning.

Motion commands can be applied to coupled slave axes, if this option was explicitly activated in the axis parameters. A motion command such as MC_MoveAbsolute then automatically leads to decoupling of the axis, after which the command is executed. In this case the only available BufferMode is "Aborting".

MC_MoveAbsolute 2: Inputs

VAR_INPUT
    Execute      : BOOL;
    Position     : LREAL; 
    Velocity     : LREAL; 
    Acceleration : LREAL; 
    Deceleration : LREAL; 
    Jerk         : LREAL;
    BufferMode   : MC_BufferMode;
    Options      : ST_MoveOptions;
END_VAR

Name

Type

Description

Execute

BOOL

The command is executed with a rising edge.

Position

LREAL

Absolute target position to be used for positioning.

Velocity

LREAL

Maximum travel velocity (>0).

Acceleration

LREAL

Acceleration (≥0)
If the value is 0, the standard acceleration from the axis configuration in the System Manager is used.

Deceleration

LREAL

Deceleration (≥0)
If the value is 0, the standard deceleration from the axis configuration in the System Manager is used.

Jerk

LREAL

Jerk (≥0)
At a value of 0, the standard jerk from the axis configuration in the System Manager is applied.

BufferMode

MC_BufferMode

Is evaluated if the axis is already executing another command. MC_MoveAbsolute becomes active after the current command or aborts it. Transition conditions from the current to the next command are also determined by the BufferMode. If the command is applied to a coupled slave axis, the only available BufferMode is "Aborting". A second function block is always required to use the BufferMode. It is not possible to trigger a move function block with new parameters while it is active.

Options

ST_MoveOptions

Data structure containing additional, rarely used parameters. The input can normally remain open.

See also: General rules for MC function blocks

MC_MoveAbsolute 3: Inputs/outputs

VAR_IN_OUT
    Axis : AXIS_REF;
END_VAR

Name

Type

Description

Axis

AXIS_REF

Axis data structure that unambiguously addresses an axis in the system. Among other parameters it contains the current axis status, including position, velocity or error state.

MC_MoveAbsolute 4: Outputs

VAR_OUTPUT
    Done           : BOOL;
    Busy           : BOOL;
    Active         : BOOL;
    CommandAborted : BOOL;
    Error          : BOOL;
    ErrorID        : UDINT;
END_VAR

Name

Type

Description

Done

BOOL

TRUE when the target position has been reached.

Busy

BOOL

TRUE as soon as the command is started with "Execute" and as long as the movement command is processed. If "Busy" is FALSE, the function block is ready for a new order. At the same time, one of the outputs "Done", "CommandAborted" or "Error" is set.

Active

BOOL

Indicates that the command is executed. If the command was buffered, it becomes active once a running command is completed.

CommandAborted

BOOL

TRUE if the command could not be executed completely. The axis was stopped or the current command was replaced by another Move command.

Error

BOOL

TRUE, if an error occurs.

ErrorID

UDINT

If the error output is set, this parameter supplies the error number.

See also: General rules for MC function blocks

MC_MoveAbsolute 5:
  • "Target Position Monitoring" is activated (standard case): when the logical positioning end is reached (the NC setpoint generation is finished and the HasJob bit is FALSE) AND afterwards the InPositionArea bit has become TRUE, then the Done output is set to TRUE.
  • "Position Range Monitoring" is activated ("Target Position Monitoring" is not active): when the logical positioning end is reached (the NC setpoint generation is finished and the HasJob bit is FALSE) AND afterwards the InPositionArea bit has become TRUE, then the Done output is set to TRUE.
  • Neither "Target Position Monitoring" nor "Position Range Monitoring" is activated: the Done output is set immediately when the logical positioning end is reached (the NC setpoint generation is ended and the HasJob bit is FALSE).

Requirements

Development environment

Target system type

PLC libraries to include

TwinCAT v3.0.0

PC or CX (x86 or x64)

Tc2_MC2