MC_MoveModulo

The function block MC_MoveModulo is used to execute a positioning operation, which refers to the modulo position of an axis. The basis for a modulo rotation is the adjustable parameter "Modulo Factor" of the AXIS_REF structure (Axis.Parameter.ModuloFactor, e.g. 360°). A distinction is made between three possible start types, depending on the "Direction" input.

Positioning in positive direction
Positioning in negative direction
Positioning along shortest path

Starting an axis from standstill

If an axis is started from standstill with MC_MoveModulo , it is possible to specify positions greater than or equal to 360°, in order to perform additional full turns.

Special cases

Particular attention should be paid to the behavior when requesting one or more complete modulo rotations. No movement is performed if the axis is at an exact set position of 90° and is positioned at 90°, for example. If 450° in positive direction is requested, the axis performs one rotation. The behavior can be different following an axis reset, because the reset will cause the current actual position to be adopted as the set position. This means that the axis is no longer exactly at 90°, but slightly below or above this value. These cases will give rise either to a minimum positioning to 90 degrees, or on the other hand a complete rotation.

Depending on the use case, it may be more effective for complete modulo rotations to calculate the desired target position on the basis of the current absolute position, and then to position using the function block MC_MoveAbsolute.

Inputs

VAR_INPUT
    Execute      : BOOL;
    Position     : LREAL; 
    Velocity     : LREAL; 
    Acceleration : LREAL; 
    Deceleration : LREAL; 
    Direction    : MC_Direction;
    Options      : ST_MoveOptions;
END_VAR

Name	Type	Description
Execute	BOOL	The command is executed with a rising edge.
Position	LREAL	Modulo target position to be used for positioning. If the axis is started from standstill, positions greater than 360° result in additional turns. Negative positions are not permitted.
Velocity	LREAL	Maximum travel velocity (>0).
Acceleration	LREAL	Acceleration (≥0)
Deceleration	LREAL	Deceleration (≥0)
Direction	MC_Direction	Positive or negative direction of travel (type MC_Direction). If the axis is started during a motion, the direction may not be reversed.
Options	ST_MoveOptions	Data structure (ST_MoveOptions) containing additional, rarely used parameters. The input can normally remain unused.

	See also: General rules for MC function blocks.

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.

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.