MC_Stop

Description

This function block aborts the active move, removes the next move from the queue, performs a controlled stop at the specified deceleration rate, and switches the axis to Stopping state.

MC_Stop cannot be aborted. This means that, while in Stopping state, no function block can command any motion on the axis. The axis remains in Stopping state until it reaches zero velocity and the Execute input is low. The application program can hold the axis in Stopping state even after it reaches zero velocity by leaving the Execute input high.

Figure 7-121: MC_Stop

Time Diagram

The example below shows the behavior of the combination of a MC_Stop FB with a MC_MoveVelocity FB.

• A rotating axis is ramped down with FB2 MC_Stop
• The axis rejects motion commands as long as MC_Stop parameter “Execute” = TRUE

FB1 MC_MoveVelocity reports an error indicating the busy MC_Stop command.

• 
  
• 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 stop the axis. It can be held high to prevent any other moves from being queued
	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	—
Deceleration	Description	Trapezoidal: Deceleration rate S-curve: Maximum deceleration
	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	—

Output

Done	Description	Indicates the axis has reached zero velocity AND the Execute input is low
	Data type	BOOL
Busy	Description	High from the time the Execute input goes high until the axis reaches zero velocity AND the Execute input is low
	Data type	BOOL
Active	Description	High from the time the MC_Stop move becomes the active move, until the axis reaches zero velocity AND the Execute input is low
	Data type	BOOL
Error	Description	Indicates an invalid input was specified
	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_Stop ST example *)

Inst_MC_Stop( StopRequest , Axis1, 100.0, 100.0 ); //Inst_MC_Stop is an instance of MC_Stop function block


StopComplete := Inst_MC_Stop.Done;     //store the Done output into a user defined variable

StopActive := Inst_MC_Stop.Active;     //store the Active output into a user defined variable

StopError := Inst_MC_Stop.Error;       //store the Error output into a user defined variable	

Ladder Diagram

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