MC_MoveRelative

Description

This function block executes a single-axis move for a specified distance to perform incremental motion.

Figure 7-140: MC_MoveRelative

Time Diagram

The following figure shows the example of the combination of two relative move FunctionA 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. Blocks:

• The left part of timing diagram illustrates the case if the Second Function BlockA function block groups an algorithm and a set of private data. It has inputs and outputs. is called after the First one. If First reaches the commanded distance 6000 (and the velocity is 0) then the output Done causes the Second FB to move to the distance 10000
• The right part of the timing diagram illustrates the case if the Second move Function Blocks starts the execution while the First FB is still executing. In this case the First motion is interrupted and aborted by the Test signal during the constant velocity of the First FB. The Second FB adds on the actual position of 3250 the distance 4000 and moves the axis to the resulting position of 7250

• 
  
• This function block starts a motion-related action and therefore stores data for calculations and error checking. Please see Calling Function Blocks Multiple Times in the Same Cycle if you are using a dual-core controller.

Arguments

For more detail on how inputs and outputs work, refer to PLCopen Function Blocks - General Rules

Input

Execute	Description	Requests to queue the move
	Data type	BOOL
	Range	0, 1
	Unit	N/A
	Default	—
Axis	Description	Name of a declared instance of the AXIS_REF library function. For more details,About Axis Name and Number
	Data type	AXIS_REF
	Range	[1,256]
	Unit	N/A
	Default	—
Distance	Description	Distance
	Data type	LREAL
	Range	—
	Unit	User unit
	Default	—
Velocity	Description	Velocity setpointSetpoint is the target value that an automatic control system, for example PID controller, will aim to reach
	Data type	LREAL
	Range	—
	Unit	User unit/sec
	Default	—
Acceleration	Description	Trapezoidal: Acceleration rate S-curve: Maximum acceleration
	Data type	LREAL
	Range	—
	Unit	User unit/sec2
	Default	—
Deceleration	Description	Trapezoidal: Deceleration rate S-curve: Unused
	Data type	LREAL
	Range	—
	Unit	User unit/sec2
	Default	—
JerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time	Description	Trapezoidal: 0 S-curve: Constant jerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time
	Data type	LREAL
	Range	—
	Unit	User unit/sec3
	Default	—
BufferMode	Description	0 = abort 1 = buffer 2 = blend to active 3 = blend to next 4 = blend to low velocity 5 = blend to high velocity See table in Buffer Modes
	Data type	SINT
	Range	[0,5]
	Unit	N/A
	Default	—

Output

Done	Description	Indicates the move completed successfully. The Command Position has reached the endpoint.
	Data type	BOOL
Busy	Description	High from the moment the Execute input is one-shot to the time the move is ended
	Data type	BOOL
Active	Description	Indicates this move is the active move
	Data type	BOOL
CommandAborted	Description	Indicates the move was aborted
	Data type	BOOL
Error	Description	Indicates an invalid input was specified or the move was terminated due to an error
	Data type	BOOL
ErrorID	Description	Indicates the error if Error output is set to TRUE See table in PLCopen Function Block ErrorID Output
	Data type	INT

Example

Structured Text

(* MC_MoveRelative ST example *)

Inst_MC_MoveRelative( MovRelReq, Axis1, 10.0, 200.0,150.0, 150.0, 0,0 );

MovRelDone := Inst_MC_MoveRelative.Done;  //store Done output into user defined variable

See also how this function is used in the Hole punch project here

Ladder Diagram

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