MC_AxisSetDefaults

Description

MC_AxisSetDefaults sets the default kinematic variables for MC_MoveDirAbs and MC_MoveDirRel. These variables are only used with the MC_MoveDir function blocks.

Each axis within the group must have the default kinematic parameters of Velocity, Acceleration, Deceleration, and JerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time set to values greater than zero. A non-zero Jerk value will perform an S-Curve rather than a trapezoidal move. Each axis within the group must have these values set before a direct move can be started.

• 
  
• Jerk with a non-zero value is currently not supported for coordinated motion. Jerk parameters are currently ignored.

The function block returns an error if the group state is not GroupStandby or GroupDisabled.

Figure 8-178: MC_AxisSetDefaults

• 
  
• 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.

Related Functions

MC_MoveDirAbs, MC_MoveDirRel, MC_ErrorDescription

Coordinated Motion, the top-level topic for Coordinated Motion.

See also:

• Differences Between Functions and Function Blocks
• Calling a Function

Arguments

Input

Execute	Description	On the rising edgeA rising edge is the transition of a digital signal from low to high. It is also called positive edge, request to set the default kinematic parameters.
	Data type	BOOL
	Range	0, 1
	Unit	N/A
	Default	—
Axis	Description	Reference to the axis which will have its default kinematic parameters set.
	Data type	AXIS_REF
	Range	—
	Unit	N/A
	Default	—
Velocity	Description	The default velocity.
	Data type	LREAL
	Range	0 < Velocity < ( 20 * Acceleration ) and 0 < Velocity < ( 20 * Deceleration) See Limitations on Acceleration and Jerk for more information.
	Unit	User units per second
	Default	—
Acceleration	Description	Trapezoidal: Acceleration rate S-curve: Maximum acceleration see "Selection of Acceleration and Jerk Parameters for Function Blocks"
	Data type	LREAL
	Range	( Velocity / 20 ) < Acceleration < ( 2 * Jerk ) See Limitations on Acceleration and Jerk for more information.
	Unit	User units per second2
	Default	—
Deceleration	Description	Trapezoidal: Deceleration rate S-curve: Unused
	Data type	LREAL
	Range	( Velocity / 20 ) < Deceleration < ( 2 * Jerk )
	Unit	User unit per second2
	Default	—
Jerk	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 Currently the Jerk value is ignored for motion. Only trapezoidal motion is supported. see "Selection of Acceleration and Jerk Parameters for Function Blocks"
	Data type	LREAL
	Range	( Velocity / 20 ) < Acceleration < ( 2 * Jerk ) and ( Velocity / 20 ) < Deceleration < ( 2 * Jerk )
	Unit	User units per second3
	Default	—

Output

Done	Description	If True, then the command completed successfully.
	Data type	BOOL
Error	Description	If True, then an error has occurred
	Data type	BOOL
ErrorID	Description	Indicates the error if Error output is set to TRUE. See the table in PLCopen Function Block ErrorID Output.
	Data type	DINT

Example

Structured Text

 (* ST"Structured text"
A high-level language that is block structured and syntactically resembles Pascal MC_AxisSetDefaults Example *)

default_velocity       := 50.0; 
default_acceleration   := 250.0;
default_deceleration   := 300.0;
default_jerk           := 1000.0;

Inst_MC_AxisSetDefaults ( TRUE, CoordAxis1_ref, default_velocity, default_acceleration, default_deceleration, default_jerk);

Instruction List

            BEGIN_IL"Instruction list"
This is a low-level language and resembles assembly
     CAL Inst_MC_AxisSetDefaults( TRUE, CoordAxis1_Ref, default_velocity, default_acceleration, default_deceleration, default_jerk)
END_IL

Function Block Diagram

Ladder Diagram

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