MC_MoveContinuousAbsolute (FB)

FUNCTION_BLOCK MC_MoveContinuousAbsolute

This function block commands a controlled motion to a specified absolute position ending with the specified velocity.

• If the commanded position is reached and no new motion command is put into the buffer, the axis continues to run with the specified “EndVelocity”.

• The function block will start the axis with state DiscreteMotion, while positioning.

• It will change to state Continuous Motion (meaning: it will not stop by itself) with EndVelocity <> 0.

• It will change to standstill with EndVelocity = 0.

One use case for MC_MoveContinuousAbsolute is a linear cutter. One linear axis that is carrying a laser device that is used to cut a workpiece

Start from lrIdlePos.

1. Move the laser with fast velocity over the position lrStartCutPos. The laser is off during this movement

2. Turn back and make sure to have the speed lrCutVelocity when at lrStartCutPos. At this position, switch the laser on

3. Travel over the work piece with this constant speed while the laser is on

4. When reaching lrEndCutPos switch off the laser and move back to idle position with fast velocity

During the cutting process the laser must be moved with a fix velocity, no acceleration or deceleration phase can be tolerated. The laser must be moved to its waiting position after the cutting is done

Example

The explained movement can be achieved with the function block MC_MoveContinuousAbsolute in the following way:

Started with a rising edge of xStartCuttingCycle, the instance “mca” of MC_MoveContinuousAbsolute will move the axis with “lrFastVelocity” over “lrStartCutPos”, turn back and have the speed “lrCutVelocity” when reaching “lrStartCutPos” again in negative direction. In this point in time, “InEndVelocity” is set and the laser is switched on. As no other motion function block interrupts this movement, MC_MoveContinuousAbsolute will keep travelling in negative direction with the current speed. After the axis has overstepped the position “lrEndPos”, where the laser is switched off, the MC_MoveAbsolute instance “ma” moves the axis with high speed to its idle position

Note

Input validation is done at the rising edge of Execute. If function block is in Active/Busy state, new value at input will not be validated. If value passed is invalid function block will continue execution with last valid value.

InOut:

Scope	Name	Type	Comment
Input	Execute	BOOL	Starts the function block at rising edge
	ContinuousUpdate	BOOL	Decide if new input parameters are processed during the movement
	Position	LREAL	[u] Reference position. Range: Maximum range is 16#7FFFFFFF in increments, if configured in units, range will be limited to equivalent of 16#7FFFFFFF increments
	EndVelocity	LREAL	[u/s] Signed value for the end veloicty, determines the direction when ending the positioning movement
	Velocity	LREAL	[u/s] Value of the maximum velocity (not necessarily reached). Range: >0
	Acceleration	LREAL	[u/s°°2] Value of the acceleration (increasing energy of the motor). Range: >0,If value = 0, Acceleration will be equal to parameter paraMaxAccelerationAppl.If value > 0 and <= 1,Acceleration will be limited to 1.
	Deceleration	LREAL	[u/s°°2] Value of the deceleration (decreasing energy of the motor). Range: >0,If value = 0, Deceleration will be equal to parameter paraMaxDecelerationAppl.If value > 0 and <= 1,Deceleration will be limited to 1.
	Jerk	LREAL	[u/s°°3] Value of the jerk. Range: >=0
	Direction	MC_Direction	Positive, Shortest, Negative, Current
	BufferMode	MC_BufferMode	Not supported, default mcABORTING used
Output	InEndVelocity	BOOL	Commanded position finally reached
	Busy	BOOL	The function block is not finished
	Active	BOOL	Indicates that the function block has control on the axis
	CommandAborted	BOOL	Command is aborted by another command from other PLCopen function block
	Error	BOOL	Signals that error has occurred within function block
	ErrorID	ERROR_ID	Error identification. For error details refer to Enumeration ERROR_ID
Inout	Axis	Axis_Ref	Reference to axis